JP2022020471A - Image formation apparatus and exposure amount adjustment method - Google Patents

Abstract

To suppress the density variation of an image due to the degradation of an image carrier.SOLUTION: An image formation apparatus according to an embodiment of the present invention comprises: an image carrier; an exposure unit which exposes the image carrier; a control unit which controls the exposure unit; an electrification member which electrifies the image carrier; a static elimination unit which eliminates the static electricity of the image carrier; a voltage application unit which applies the voltage to the electrification member; a current detection unit which detects the current flowing from the voltage application unit to the image carrier; and a potential detection unit which detects the surface potential of the image carrier on the basis of the current. The control unit adjusts the exposure amount by the exposure unit on the basis of the surface potential after the static elimination by the static elimination unit and the initial value of the surface potential.SELECTED DRAWING: Figure 2

Description

The present invention relates to an image forming apparatus and an exposure amount adjusting method.

Conventionally, in an electrophotographic image forming apparatus, in order to suppress fluctuations in image density, exposure to the image carrier and charging members are applied based on the pattern density on the image carrier, the surface potential of the image carrier, and the like. A configuration for controlling the applied voltage is known.

Further, in a configuration in which exposure to an image carrier is controlled to suppress fluctuations in image density, a configuration is disclosed in which exposure is controlled based on a direct current flowing through the charging member when a voltage is applied to the charging member. (For example, see Patent Document 1).

However, with the configuration of Patent Document 1, it may not be possible to suppress fluctuations in image density due to deterioration of the image carrier.

An object of the present invention is to suppress fluctuations in image density due to deterioration of the image carrier.

The image forming apparatus according to one aspect of the present invention includes an image carrier, an exposure unit that exposes the image carrier, a control unit that controls the exposure unit, a charging member that charges the image carrier, and the like. A static elimination unit that eliminates static electricity from the image carrier, a voltage application unit that applies a voltage to the charging member, a current detection unit that detects a current flowing from the voltage application unit to the image carrier, and the image based on the current. It has a potential detection unit that detects the surface potential of the carrier, and the control unit is exposed by the exposure unit based on the surface potential after static elimination by the static elimination unit and the initial value of the surface potential. Adjust the amount.

According to the present invention, it is possible to suppress fluctuations in image density due to deterioration of the image carrier.

It is a block diagram which shows the structural example of the image forming apparatus which concerns on 1st Embodiment. It is a block diagram which shows the functional structure example of the control part which concerns on 1st Embodiment. It is a figure which shows the example of the relationship between the exposure amount and the surface charge of a photoconductor. It is a flow chart of the initial value acquisition example of the image forming apparatus which concerns on 1st Embodiment. It is a flow chart of the exposure amount adjustment example of the image forming apparatus which concerns on 1st Embodiment. It is a flow chart of the initial value acquisition example of the image forming apparatus which concerns on 2nd Embodiment. It is a block diagram which shows the functional structure example of the control part which concerns on 2nd Embodiment. It is a block diagram which shows the structural example of the image forming apparatus which concerns on 3rd Embodiment.

Hereinafter, embodiments for carrying out the invention will be described with reference to the drawings. In each drawing, the same components are designated by the same reference numerals, and duplicate description will be omitted as appropriate.

Further, the embodiments shown below exemplify an image forming apparatus for embodying the technical idea of the present invention, and the present invention is not limited to the embodiments shown below. Unless otherwise specified, the shapes of the components, their relative arrangements, the values of the parameters, etc. described below are not intended to limit the scope of the present invention to that alone, but are intended to be exemplified. Is. In addition, the size and positional relationship of the members shown in the drawings may be exaggerated in order to clarify the explanation.

The image forming apparatus according to the embodiment is an electrophotographic device such as an MFP (Multifunction Peripheral / Printer / Product) or a printer.

The image forming apparatus includes an image carrier, an exposure unit that exposes the image carrier, a control unit that controls the exposure unit, a charging member that charges the image carrier, and a static elimination unit that eliminates static electricity from the image carrier. It has a voltage applying section that applies a voltage to the charging member, a current detecting section that detects the current flowing from the voltage applying section to the image carrier, and a potential detecting section that detects the surface potential of the image carrier based on the current. ..

In an electrophotographic image forming apparatus, when an image carrier such as a photoconductor deteriorates, the surface potential may not drop completely and the density of the image may fluctuate. In the embodiment, the exposure amount by the exposed unit is adjusted based on the surface potential of the image carrier after the static elimination unit is statically eliminated and the initial value of the surface potential of the image carrier. As a result, the surface potential of the image carrier is kept at the same level as the initial state, and the image density is stabilized.

Here, the initial value of the surface potential of the image carrier means the value of the surface potential of the image carrier detected by the potential detection unit in the initial state such as when the image forming apparatus is shipped or loaded. The exposure amount means the amount of light per unit time irradiated on the surface (per unit area) of the image carrier.

[First Embodiment]
First, the image forming apparatus according to the first embodiment will be described.

<Configuration example of image forming apparatus 100>
The configuration of the image forming apparatus 100 will be described with reference to FIG. FIG. 1 is a block diagram illustrating an example of the configuration of the image forming apparatus 100. Note that FIG. 1 shows only the main elements of the image forming apparatus 100 for the sake of clarity.

As shown in FIG. 1, the image forming apparatus 100 includes a photoconductor 1, an exposure unit 2, a charging roller 3, a high-voltage power supply 4, a static elimination unit 5, and a control unit 6.

The photoconductor 1 is a rotatable drum-shaped member, and is an example of an image carrier that supports a toner image of toner.

The exposure unit 2 exposes the photoconductor 1 in response to an image signal to form an electrostatic latent image on the photoconductor 1. A developing unit (not shown) develops an electrostatic latent image on the photoconductor 1, so that a toner image is formed on the photoconductor 1.

The charging roller 3 is an example of a charging member that charges the photoconductor 1. The charging roller 3 is in contact with or close to the photoconductor 1 at a distance of about several tens of microns, and is between the surface of the photoconductor 1 and the surface of the charging roller 3 due to the high voltage applied from the high voltage power supply 4. Generate a discharge. As a result, the surface of the photoconductor 1 is uniformly charged to a predetermined potential. As an example, the photoconductor 1 rotates clockwise, and the charging roller 3 rotates counterclockwise.

The high-voltage power supply 4 is an example of a voltage application unit that applies a voltage to the charging roller 3. The high-voltage power supply 4 superimposes a high-voltage DC voltage and a high-voltage AC voltage to generate a high-voltage (for example, negative voltage) charging bias, and applies the generated charging bias to the charging roller 3.

Further, the high voltage power supply 4 has a current detection circuit 41. The current detection circuit 41 is an example of a current detection unit that detects the current flowing from the high voltage power supply 4 to the photoconductor 1. The current detection circuit 41 can output a current detection signal to the control unit 6.

The static elimination unit 5 is an example of a static elimination unit that removes the electric charge charged on the photoconductor 1 and eliminates the static charge of the photosensitive member 1. The static elimination unit 5 has, for example, a light emitting diode (LED), and after the toner image on the photoconductor 1 is transferred to an intermediate transfer belt (not shown) or the like, the light emitted by the light emitting diode is exposed to light. By irradiating the body 1, the charge on the surface of the photoconductor 1 is removed to eliminate static electricity.

The control unit 6 is composed of an electric circuit and realizes various functions described below in FIG. A part of the function can be realized by software (CPU; Central Processing Unit), and can also be realized by a plurality of circuits or a plurality of software.

<Example of functional configuration of control unit 6>
Next, the functional configuration of the control unit 6 will be described with reference to FIG. FIG. 2 is a block diagram illustrating an example of the functional configuration of the control unit 6. Note that FIG. 2 shows only the main elements of the control unit 6 for the sake of clarity.

As shown in FIG. 2, the control unit 6 includes a current acquisition unit 61, a potential detection unit 62, a potential comparison unit 63, a storage unit 64, an exposure amount adjustment unit 65, an exposure control unit 66, and static elimination control. It has a portion 67.

The current acquisition unit 61 acquires a current value based on the current detection signal input from the current detection circuit 41. The function of the current acquisition unit 61 is realized by, for example, an A / D (Analog / Digital) conversion circuit or the like, and provides a digital signal indicating the current value after the A / D conversion to the potential detection unit 62.

The potential detection unit 62 predicts and detects the surface potential of the photoconductor 1 after static elimination based on a digital signal indicating a current value received from the current acquisition unit 61. The potential detection unit 62 predicts the surface potential of the photoconductor 1 after static elimination by, for example, comparing the current flowing from the charging roller 3 to the photoconductor 1 when the charging bias is applied and when it is not applied (static elimination). Can be detected.

When the potential detection unit 62 detects the surface potential of the photoconductor 1 in the initial state, the potential detection unit 62 stores the surface potential value as an initial value in the storage unit 64. When the surface potential of the photoconductor 1 is detected in a state other than the initial state, the surface potential value is provided to the potential comparison unit 63.

The storage unit 64 is realized by a storage device such as a semiconductor memory, and can store the initial value of the surface potential of the photoconductor 1.

The potential comparison unit 63 acquires the initial value of the surface potential of the photoconductor 1 from the storage unit 64. Then, the surface potential value of the photoconductor 1 detected in a state other than the initial state is compared with the initial value, the amount of change in the surface potential is calculated, and the information indicating the amount of change is provided to the exposure amount adjusting unit 65.

The exposure amount adjusting unit 65 is exposed by the exposure unit 2 so that the surface potential of the photoconductor 1 becomes equal to the initial value based on the information indicating the amount of change in the surface potential of the photoconductor 1 received from the potential comparison unit 63. Adjust the amount. For example, when the exposure unit 2 includes a semiconductor laser and the photoconductor 1 is exposed to a laser beam emitted by the semiconductor laser, the exposure amount adjusting unit 65 may use the light intensity or emission time (pulse) of the laser beam. The exposure amount can be adjusted by adjusting the time width) and the like.

The exposure control unit 66 controls the exposure of the exposure unit 2 to the photoconductor 1 according to the image signal. The static elimination control unit 67 controls static elimination of the photoconductor 1 by the static elimination unit 5.

<Example of relationship between exposure amount and surface charge of photoconductor>
Here, FIG. 3 is a diagram illustrating an example of the relationship between the exposure amount to the photoconductor by the exposed portion and the surface charge of the photoconductor. The horizontal axis of FIG. 3 shows the exposure amount, and the vertical axis shows the surface potential of the photoconductor.

As shown in FIG. 3, as the exposure amount increases, the surface potential of the photoconductor tends to decrease. The change in the surface potential of the photoconductor with the increase in the exposure amount differs depending on the image forming apparatus depending on the characteristics of the image forming apparatus, and the data of this change can be acquired at the development stage of the image forming apparatus, for example, the higher order. It can be expressed by a function.

Therefore, the exposure amount adjusting unit 65 in FIG. 2 is exposed by the exposure unit 2 using a predetermined high-order function based on the information indicating the amount of change in the surface potential of the photoconductor 1 received from the potential comparison unit 63. You can adjust the amount.

<Processing example by control unit 6>
Next, processing by the control unit 6 will be described with reference to FIGS. 4 and 5. Here, FIG. 4 is a flowchart illustrating an example of the initial value acquisition process by the control unit 6. Further, FIG. 5 is a flowchart illustrating an example of the exposure amount adjustment process by the control unit 6. This will be described with reference to the functional configuration diagram of FIG. 2 as appropriate.

(Example of initial value acquisition process)
The initial value acquisition process is a process executed in a production guarantee process at the manufacturing site of the image forming apparatus, an initial operation confirmation process such as at the time of arrival at the site where the image forming apparatus is used, and the like.

As shown in FIG. 4, first, in step S41, the static elimination control unit 67 controls the static elimination unit 5 to eliminate static electricity 1 from the photoconductor 1.

Subsequently, in step S42, the current acquisition unit 61 acquires a current value based on the current detection signal input from the current detection circuit 41. After that, the potential detection unit 62 predicts and detects the surface potential of the photoconductor 1 after static elimination based on the digital signal indicating the current value received from the current acquisition unit 61.

Subsequently, in step S43, the potential detection unit 62 stores the detected surface potential value as the initial value a in the storage unit 64.

In this way, the control unit 6 can acquire the initial value a of the surface potential of the photoconductor 1 and store it in the storage unit 64.

(Example of exposure adjustment processing)
The exposure amount adjustment process is a process executed when the image forming apparatus is in a state other than the initial state. For example, the exposure amount adjustment process can be executed every time the image forming apparatus performs a static elimination operation in image forming. Further, after a predetermined time has elapsed after adjusting the exposure amount, after a predetermined number of images have been formed, after the photoconductor has traveled a predetermined distance (after being rotated a predetermined number of times), and the like. The exposure amount adjustment process may be executed at a predetermined timing.

As shown in FIG. 5, first, in step S51, the static elimination control unit 67 controls the static elimination unit 5 to eliminate static electricity 1 from the photoconductor 1.

Subsequently, in step S52, the current acquisition unit 61 acquires a current value based on the current detection signal input from the current detection circuit 41. After that, the potential detection unit 62 predicts and detects the surface potential b of the photoconductor 1 after static elimination based on the digital signal indicating the current value received from the current acquisition unit 61. After that, the current acquisition unit 61 provides the detected surface potential value to the potential comparison unit 63.

Subsequently, in step S53, the potential comparison unit 63 obtains the initial value a of the surface potential of the photoconductor 1 with reference to the storage unit 64, and determines whether or not the initial value a is equal to the surface potential b.

If it is determined in step S53 that they are equal (step S53, Yes), the process ends. On the other hand, if it is determined that they are not equal (step S53, No), the process proceeds to step S54.

Subsequently, in step S54, the exposure amount adjusting unit 65 adjusts the exposure amount by the exposure unit 2 based on the information indicating the amount of change in the surface potential of the photoconductor 1 received from the potential comparison unit 63. For example, the exposure amount by the exposure unit 2 is adjusted by using a predetermined high-order function based on the change amount c of the surface potential b with respect to the initial value a.

In this way, the control unit 6 can adjust the amount of exposure to the photoconductor 1 by the exposure unit 2.

<Action and effect of image forming apparatus 100>
Next, the operation and effect of the image forming apparatus 100 will be described.
In the image forming apparatus, when the photoconductor deteriorates, the surface potential of the photoconductor may not be completely reduced. This tendency is the same at the time of static elimination and at the time of exposure for image formation. When the surface potential at the time of image formation does not drop completely (difference from the initial state appears), the density of the image formed on the recording medium such as paper by the image forming apparatus fluctuates.

In the present embodiment, the amount of change from the initial value of the photoconductor surface potential is detected based on the surface potential of the photoconductor (image carrier) after static elimination by the static elimination unit and the initial value of the photoconductor surface potential. Based on this amount of change, the amount of exposure by the exposed portion is adjusted so that the surface potential of the photoconductor drops to the same level as the initial value.

As a result, the surface potential of the photoconductor can be maintained at the same level as the initial state, and the image density can be stabilized.

[Second Embodiment]
Next, the image forming apparatus 100a according to the second embodiment will be described. The same component numbers as those described in the first embodiment are designated by the same part numbers, and duplicate explanations will be omitted as appropriate.

In the present embodiment, when the image carrier is replaced, the initial value is acquired and stored in the storage unit. FIG. 6 is a block diagram illustrating an example of the functional configuration of the control unit 6a included in the image forming apparatus 100a. As shown in FIG. 6, the control unit 6a has an exchange determination unit 68.

The replacement determination unit 68 determines whether or not the photoconductor 1 has been replaced with a new photoconductor or the like. This determination can be made based on an input indicating the replacement of the photoconductor 1 by the user of the image forming apparatus 100a using the operation panel of the image forming apparatus 100a. When the replacement determination unit 68 determines that the photoconductor 1 has been replaced, the control unit 6a detects the surface potential of the replaced photoconductor 1 and stores the photoconductor 1 in the storage unit 64 as an initial value. As a result, the initial value stored in the storage unit 64 is updated.

FIG. 7 is a flowchart illustrating an example of the initial value acquisition process by the control unit 6a.

As shown in FIG. 7, first, in step S71, the exchange determination unit 68 determines whether or not the photoconductor 1 has been exchanged.

If it is determined in step S71 that the product has been replaced (step S71, Yes), the process proceeds to step S72. On the other hand, if it is determined that the replacement has not been performed (step S71, No), the process ends.

Since the processing of steps S72 to S74 is the same as the processing of steps S41 to S43 of FIG. 4, duplicated description will be omitted here.

In this way, the control unit 6a can acquire the initial value of the surface potential of the photoconductor 1 and store it in the storage unit 64 when the photoconductor 1 is replaced.

As described above, in the present embodiment, when the image carrier is replaced, the initial value is acquired and stored in the storage unit, so that the photoconductor surface potential is the initial value even if the photoconductor 1 deteriorates. The amount of exposure by the exposed part can be adjusted so as to be as low as. As a result, the surface potential of the photoconductor can be maintained at the same level as the initial state, and the image density can be stabilized.

[Third Embodiment]
Next, the image forming apparatus 100b according to the third embodiment will be described. The same component numbers as those described in the above-described embodiment are designated by the same part numbers, and duplicate explanations will be omitted as appropriate.

The image forming apparatus 100b according to the present embodiment has an image forming unit including an image carrier and a storage unit, and the control unit is a change of the surface potential with respect to the initial value after the static elimination unit eliminates static electricity from the image carrier. Adjust the exposure amount based on the amount.

FIG. 8 is a block diagram illustrating an example of the configuration of the image forming apparatus 100b. As shown in FIG. 8, the image forming apparatus 100b includes a photoconductor unit 10 and a control unit 6b.

The photoconductor unit 10 has a photoconductor 1 and a storage unit 64. The photoconductor unit 10 is a unit such as a process cartridge containing at least the photoconductor 1. In the present embodiment, for example, since a used product of the photoconductor unit 10 is assumed, the photoconductor unit 10 is established as a replacement part in units of units. Therefore, since the guarantee process is performed for each unit even at the time of production, the initial value of the surface potential can be stored in the storage unit 64 in the guarantee process.

The control unit adjusts the exposure amount by the exposure unit 2 based on the change amount of the surface potential in the photoconductor 1 after the static elimination unit 5 eliminates static electricity by referring to the initial value of the surface potential stored in the storage unit 64. do.

By doing so, even when the photoconductor unit 10 such as a used product that has been used in another image forming apparatus is used in the image forming apparatus 100b, the initial value of the surface potential of the photoconductor 1 is used. It is possible to suppress fluctuations in the density of the image. Even if the photoconductor unit is replaced with another unit, since the initial value of the surface potential of the unit is stored in the other unit, the exposure amount can be adjusted by using the initial value.

[Other preferred embodiments]
In addition to the above embodiments, the image forming apparatus may be configured so that the exposed unit includes a static elimination unit and the image carrier is statically eliminated by the exposure of the exposed unit. For example, the image carrier is exposed and statically eliminated by irradiating the image carrier such as a photoconductor with light from a semiconductor laser, LED, or the like used in the exposure unit. This makes it possible to simplify the configuration of the image forming apparatus.

Although examples of embodiments of the present invention have been described above, the present invention is not limited to such specific embodiments, and various aspects are described within the scope of the gist of the present invention described in the claims. It can be transformed and changed.

In the above-described embodiment, the configuration in which the image forming apparatus has a storage unit is exemplified, but the external server or the like has a storage unit, and the image forming apparatus refers to the storage unit of the external server via the network. , It is also possible to acquire the initial value of the surface potential of the photoconductor.

Further, as the exposure unit according to the embodiment, either a raster type exposure unit that scans a semiconductor laser or a solid-state writing type exposure unit that uses an LED array can be applied.

Further, the numbers such as the ordinal number and the quantity used above are all exemplified for concretely explaining the technique of the present invention, and the present invention is not limited to the exemplified numbers. Further, the connection relationship between the components is exemplified for concretely explaining the technique of the present invention, and the connection relationship for realizing the function of the present invention is not limited to this.

Further, the division of blocks in the functional block diagram is an example, and even if a plurality of blocks are realized as one block, one block is divided into a plurality of blocks, and / or some functions are transferred to another block. good. Further, the functions of a plurality of blocks having similar functions may be processed by a single hardware or software in parallel or in a time division manner.

Further, each function of the embodiment described above can be realized by one or a plurality of processing circuits. Here, the "processing circuit" as used herein is a processor programmed to perform each function by software, such as a processor implemented by an electronic circuit, or a processor designed to execute each function described above. It shall include devices such as ASIC (Application Specific Integrated Circuit), DSP (digital signal processor), FPGA (field programmable gate array) and conventional circuit modules.

The embodiment also includes an exposure amount adjusting method. For example, the exposure amount adjusting method includes an exposure step of exposing the image carrier, a control step of controlling the exposure step, a charging step of charging the image carrier with a charging member, and static elimination of the image carrier. A step, a voltage application step of applying a voltage to the charging member by a voltage application portion, a current detection step of detecting a current flowing from the voltage application portion to the image carrier, and a current detection step of detecting the image carrier based on the current. A potential detection step of detecting the surface potential is performed, and in the control step, the exposure amount in the exposure step is adjusted based on the surface potential after static elimination in the static elimination step and the initial value of the surface potential. do. By such an exposure amount adjusting method, the same effect as the above-mentioned image forming apparatus can be obtained.

1 Photoreceptor (an example of an image carrier)
2 Exposure unit 3 Charging roller (example of charging member)
4 High-voltage power supply 41 Current detection circuit 5 Static elimination unit 6 Control unit 61 Current acquisition unit 62 Potential detection unit 63 Potential comparison unit 64 Storage unit 65 Exposure adjustment unit 66 Exposure control unit 67 Static elimination control unit 68 Replacement determination unit 100 Image forming device

Japanese Unexamined Patent Publication No. 2016-218155

Claims (7)

With the image carrier,
An exposed portion that exposes the image carrier and an exposed portion.
A control unit that controls the exposure unit and
A charging member that charges the image carrier and
A static elimination unit that eliminates static electricity from the image carrier,
A voltage applying part that applies a voltage to the charging member,
A current detection unit that detects the current flowing from the voltage application unit to the image carrier, and
It has a potential detection unit that detects the surface potential of the image carrier based on the current, and has.
The control unit is an image forming apparatus that adjusts the exposure amount by the exposure unit based on the surface potential after static elimination by the static elimination unit and the initial value of the surface potential. The image forming apparatus according to claim 1, wherein the control unit adjusts the exposure amount based on the amount of change with respect to the initial value after the static elimination unit statically eliminates the image carrier. It has a storage unit for storing the initial value, and has a storage unit.
Claim 1 or 2 in which the control unit adjusts the exposure amount based on the surface potential after the static elimination unit statically eliminates the image carrier and the initial value stored in the storage unit. The image forming apparatus according to. The image forming apparatus according to claim 3, wherein the control unit acquires the initial value when the image carrier is replaced and stores the initial value in the storage unit. It has an image forming unit including the image carrier and a storage unit for storing the initial value.
The image forming apparatus according to any one of claims 1 to 4, wherein the control unit adjusts the exposure amount based on the surface potential after static elimination by the static elimination unit and the initial value. The exposed unit includes the static elimination unit.
The image forming apparatus according to any one of claims 1 to 5, wherein the static elimination unit eliminates static electricity from the image carrier by exposure by the exposure unit. The exposure process for exposing the image carrier and
A control process that controls the exposure process and
A charging step of charging the image carrier with a charging member, and
The static elimination step of statically eliminating the image carrier and the static elimination step.
A voltage application step of applying a voltage to the charging member by a voltage application unit, and
A current detection step of detecting a current flowing from the voltage application unit to the image carrier, and
A potential detection step of detecting the surface potential of the image carrier based on the current is performed.
In the control step, an exposure amount adjusting method for adjusting the exposure amount in the exposure step based on the surface potential after static elimination in the static elimination step and the initial value of the surface potential.

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