JPH0635312A - Image forming device - Google Patents

Abstract

PURPOSE:To suppress a maintenance cost and a running cost by extending the interval between periodical maintenance by reducing the scattered quantity of toner from a developing roller and furthermore to suppress variation in the image density and the deterioration of the image quality by varying the linear velocity of the developing roller according to the situation where the image forming action is carried out. CONSTITUTION:The device is provided with a temperature sensor 116 detecting the environmental temperature in the vicinity of a photosensitive body, a toner sensor 117 detecting the toner density of a developing part, a developing motor 204 rotating the developing roller, a developing motor driver 205 driving the developing motor 204 and a control part 201 switching the rotational speed of the developing motor 204 based on the image range/non-image range of the photosensitive body, the temperature detected by the temperature sensor 116, the toner density detected by a toner sensor 117 and the condition of the use of the device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic image forming apparatus such as a copying machine, a facsimile or a printer. More specifically, the linear speed of a developing roller is set independently of the linear speed of a photoconductor. The present invention relates to an image forming apparatus that changes.

[0002]

2. Description of the Related Art In an image forming apparatus using an electrophotographic method, an electrostatic latent image formed by exposing a photoconductor whose surface is charged is subjected to a developing process for attaching toner. This developing process is performed by transferring the toner in the developing section to the photoconductor by using a developing roller arranged to face the photoconductor. The linear velocity of the developing roller at this time is set in advance, and the velocity is usually set to be the same as or faster than the linear velocity of the photoconductor.

[0003]

However, according to the conventional image forming apparatus, the linear velocities of the photoconductor and the developing roller are set in advance, and when the image forming operation is started, the photoconductor and the developing roller are set to this setting. Since it is driven at the specified linear velocity, the amount of toner scattered from the developing roller during the image forming operation increases for the following reasons. Therefore, periodic maintenance such as cleaning of the inside of the apparatus must be performed at short intervals. There was a problem of increasing maintenance costs.

Here, the above-mentioned problems will be described in detail. The amount of toner scattering from the developing roller tends to increase as the linear velocity of the developing roller increases. Further, one image forming operation includes a period from the start of the image forming operation to the start of the developing process (developing process start period), a period during which the developing process is being executed (developing process period), and a developing process. Can be classified into three periods, that is, a period from the end of the above to the end of the image forming operation (development processing end period). Since the developing process is not performed during the developing process start period and the developing process end period, the developing roller is idling, but since these periods account for a large proportion of the image forming operation period,
The amount of toner scattered from the developing roller during these periods also accounts for a large proportion of the total amount of toner scattered during the image forming operation period.

There are one-component type (toner only) and two-component type (toner and carrier) developers, and the developing method is a positive-positive process in which the photosensitive member is not exposed. There are a positive development method in which toner adheres, and a reversal development method in which toner adheres to an exposed portion on a photosensitive member by a negative-positive process. Like this,
Since there are many types of developing methods, the number of combinations increases, but generally, the faster the linear velocity of the developing roller is, the faster the linear velocity of the photosensitive member is, the larger the toner adhesion amount is, that is, the image density (ID). Is known to tend to get darker. Therefore, when the linear velocity of the developing roller is high outside the development processing period, the toner easily adheres to the photoconductor even in the non-image area, so that the toner is wasted and the running cost is increased.

Further, in the developing process, when the toner remaining amount in the developing portion changes, the toner amount transferred to the photoconductor by the developing roller also changes, so that the toner image formed on the photoconductor is changed according to the toner remaining amount. However, there is a problem in that the image quality also deteriorates due to the fluctuation of the ID.

Further, when the environmental temperature fluctuates, the characteristic (charging characteristic, photosensitive characteristic) of the photoconductor also fluctuates due to this environmental change, so that the toner image formed on the photoconductor is changed with the change of the characteristic of the photoconductor. There is also a problem that the ID fluctuates and the image quality deteriorates.

Further, the characteristics of the photosensitive member are
Since the number of continuous image formations varies depending on the usage status of the apparatus such as the rest time, the ID of the toner image formed on the photoconductor fluctuates depending on the usage status of the apparatus, and the image quality deteriorates. There were also points.

The present invention has been made in view of the above, and by reducing the amount of toner scattered from the developing roller, it is possible to extend the regular maintenance interval, suppress the maintenance cost and the running cost.
The purpose of.

Further, the present invention has been made in view of the above, and changes the linear velocity of the developing roller according to the situation in which the image forming operation is performed, thereby suppressing the fluctuation of the image density,
A second object is to suppress deterioration of image quality.

[0011]

In order to achieve the above object, the present invention provides a photoreceptor for forming an electrostatic latent image according to a document image and a visible electrostatic latent image formed on the photoreceptor. An image forming apparatus provided with a developing roller for forming an image is provided with a control means for controlling the rotation speed of the developing roller based on the image area / non-image area of a photoconductor. .

In order to achieve the above object, the present invention provides a photosensitive member which forms an electrostatic latent image according to an original image and a developing device which visualizes the electrostatic latent image formed on the photosensitive member. An image forming apparatus including a roller and a toner remaining amount detecting means for detecting the toner remaining amount, and an image including a control means for controlling the rotation speed of the developing roller based on the detection result of the toner remaining amount detecting means. A forming apparatus is provided.

In order to achieve the above-mentioned object, the present invention provides a photoreceptor for forming an electrostatic latent image according to an original image and a developing for visualizing the electrostatic latent image formed on the photoreceptor. An image forming apparatus including a roller and a temperature detecting unit that detects a temperature in the vicinity of a photoconductor, the image forming apparatus including a control unit that controls a rotation speed of a developing roller based on a detection result of the temperature detecting unit. Is provided.

Further, in order to achieve the above-mentioned object, the present invention provides a photoreceptor for forming an electrostatic latent image according to an original image, and a developing for visualizing the electrostatic latent image formed on the photoreceptor. In an image forming apparatus including a roller, control means for controlling the rotation speed of the developing roller based on the usage status of the apparatus such as the number of times image formation is continuously performed on the photoconductor and the idle time of the photoconductor. And an image forming apparatus including:

[0015]

In the image forming apparatus according to the present invention, the amount of toner scattering from the developing roller is suppressed by lowering the linear velocity of the developing roller during the period when the developing process is not performed during the image forming operation.

Further, the image forming apparatus according to the present invention uses the developing roller based on the usage status of the apparatus such as the amount of toner remaining in the developing section, the ambient temperature, the number of times image formation is continuously performed, and the idle time of the photoconductor. Change the linear velocity of.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view showing a schematic configuration of an image forming apparatus 100 according to this embodiment. A drum-shaped photosensitive member 101, a charger 102 for charging the surface of the photosensitive member 101 by corona discharge, and a laser light source are driven. ，
A laser beam emitted from the laser light source is guided onto the photoconductor 101, and an optical unit 103 that writes an image by exposing the photoconductor 101 and a developing roller 104a that transfers toner to the photoconductor 101 are provided. A developing unit 104 that develops the electrostatic latent image formed above, and paper feed cassettes 105a, 105b, 105 on which recording paper is set
c, a transfer charger 106 for transferring the toner image formed on the photoconductor 101 by the developing process onto the recording paper, a separation charger 107 for separating the recording paper after the transfer process from the photoconductor 101, and a transfer process. Cleaning unit 108 for removing the toner remaining on the photoconductor 101 after the completion of the cleaning, a discharge lamp 109 for erasing the residual charge on the photoconductor 101 after the cleaning process, and the recording separated from the photoconductor 101. Conveyor belt 1 for conveying paper
10 and a fixing unit 111 for fixing the toner image on the recording paper
A switching claw 112 for switching the conveyance destination of the recording paper on which the toner image is fixed by the fixing section 111; and a re-feeding system 113 for conveying the recording paper conveyed by the switching claw 112 toward the photoconductor 101 again. Paper discharge rollers 114a, 114b, 114c for discharging the recording paper to the outside of the machine, paper discharge trays 115a, 115b for storing the recording paper discharged to the outside of the machine, and a temperature sensor for detecting the temperature in the vicinity of the photoconductor 101. 116 and a toner sensor 117 for detecting the amount of toner remaining in the developing unit 104 (toner concentration).

The operation of the above configuration will be described. When the image forming operation starts, the charging charger 102
On the photoconductor 101 charged by the optical unit 10
Laser light is emitted from 3 and its surface is exposed. The optical unit 103 drives a laser light source, reflects the laser light emitted from the laser light source on a polygon mirror that rotates at a high speed, and exposes the image on the photoconductor 101. An electrostatic latent image corresponding to the information is formed.

The developing section 104 uses a two-component developer, and rotates the developing roller 104a to transfer the toner to the photosensitive member 101. The toner transferred by the developing roller 104a is attached to the electrostatic latent image on the photoconductor 101 to form a toner image. The toner image is transferred onto the recording paper conveyed from the paper feed cassette 105a, 105b, or 105c by the action of the transfer charger 106, and the recording paper on which the transfer process is completed is neutralized by the action of the separation charger 107 and is exposed to light. Separated from body 101. After the transfer process is completed, the cleaning unit 108 removes the residual toner from the photosensitive member 101, and the static elimination lamp 109 irradiates the photosensitive member 101 with light to erase the residual charges.

The recording sheet separated from the photoconductor 101 is conveyed to the fixing section 111 by the conveying belt 110, and heat and pressure are applied in the fixing section 111, so that the transferred toner image is fixed on the recording sheet. The recording paper that has passed through the fixing unit 111 is switched to a destination by a switching claw 112,
Refeed system 113, or paper ejection rollers 114a, 114b,
It is conveyed to 114c. The recording paper conveyed to the re-feeding system 113 is similarly subjected to image formation on the other surface, and the recording paper conveyed to the paper discharge rollers 114a, 114b, 114c is discharged outside the machine. Here, the paper ejection roller 11
The recording paper discharged to the outside of the machine by 4b is output to the paper discharge tray 11
It is stored in 5a or 115b.

FIG. 2 is a block diagram showing a schematic configuration of a control system in the image forming apparatus 100. The control section 201 for controlling the entire apparatus, the temperature sensor 116, the toner sensor 117, and the photoconductor 101 are described. It is composed of a main motor 202 that is rotationally driven, a main motor driver 203 that drives the main motor 202, a developing motor 204 that rotationally drives the developing roller 104a, and a developing motor driver 205 that drives the developing motor 204.

In the above structure, the operation will be described by taking various linear velocity control of the developing roller 104a according to this embodiment as an example. First, the linear velocity control during the image forming operation will be described. One image forming operation is a period from the start of the image forming operation to the start of the developing process (developing process start period), a period during which the developing process is being executed (developing process period), and the developing process ends. After that, it can be classified into three periods, that is, a period from the end of the image forming operation (development processing end period). Although toner is scattered from the developing roller 104a, the amount of scattering is
It has been found that the higher the linear velocity of the developing roller 104a is, the higher the linear velocity of the developing roller 104a is. The linear velocity control during the image forming operation controls the linear velocity of the developing roller 104a in consideration of these points.

FIG. 3 is a timing chart showing an example of the linear velocity control operation during the image forming operation. In FIG. 3, the photosensitive member indicates whether the photosensitive member 101 at the position facing the developing roller 104a is an image area or a non-image area.
The period of 01 in the image area is a period in which the developing process is performed. Here, it is determined whether the photoconductor 101 at the position facing the developing roller 104a is the image area or the non-image area.
Controlled by the time from the start of rotation of 1 to the start of exposure by laser light, the linear velocity of the photoconductor 101, the image size formed on the photoconductor 101, the positional relationship between the exposure position and the transfer position on the photoconductor 101, and the like. The unit 201 makes the determination.

As shown in FIG. 3, by rotating the developing roller 104a at a high speed only during the developing process, the developing roller 104a is driven at a lower speed than in the case where the developing roller 104a is always rotated at a high speed. The amount of toner scattered from the developing roller 104a during the interval can be suppressed. Further, since the toner adhesion amount to the photoconductor 101 is smaller when the linear velocity of the developing roller 104a is slower, the toner adhesion amount in the non-image area of the photoconductor 101 can be suppressed and the running cost can be reduced.

When the toner scattering amount is suppressed in this way, the amount of toner scattered by the use of the device reduces the amount of dirt inside the device, so that the interval between regular maintenance can be extended and the maintenance cost can be reduced. it can. Moreover, since the interval between the periodical maintenance is lengthened, the time during which the device cannot be used due to the maintenance can be shortened, so that the efficiency of use of the device can be improved. Further, since the dirt inside the device adversely affects the drive system such as the motor inside the device, the reduction of the toner scattering amount also has the effect of reducing the adverse effects on the components of the device, the drive system, and the like. This makes it possible to extend the life of the device.

The linear velocity control during the image forming operation is as follows.
From the control unit 201 to the developing motor driver 205, S1, S
This is performed by outputting a 2-bit control signal consisting of 2. FIG. 5 shows the relationship between this control signal and the linear velocity of the developing roller 104a.

Here, switching of the rotational speed of the developing motor 204 by the developing motor driver 205 will be described. In this embodiment, a DC servo motor is used as the developing motor 204, and when the developing motor driver 205 inputs this control signal, the developing motor 204 changes the frequency control oscillation frequency dividing ratio to change the developing motor. The rotation speed of 204 is switched. Although not performed in this embodiment, if the input voltage is changed at this time by using a V / F (voltage / frequency) converter for the frequency oscillator, the rotational speed can be linearly controlled.

Next, the developing roller 104a depending on the ambient temperature
The linear velocity control will be described. This control suppresses fluctuations in the image density (ID) due to fluctuations in the characteristics (charging characteristics, photosensitive characteristics) of the photoconductor due to environmental temperature.
The environmental temperature is detected by the temperature sensor 116. Figure 4
FIG. 6 is an explanatory diagram showing the relationship between the environmental temperature and the linear velocity of the developing roller 104a that can be switched depending on the environmental temperature.

In this embodiment, a thermistor is used as the temperature sensor 116, and the fluctuation of the environmental temperature is output (voltage).
It is detected as the fluctuation of. Two thresholds are set in advance for the output of the temperature sensor 116.
Low temperature when the output of is smaller than the threshold of the smaller value,
It is determined that the temperature is high when the output of the temperature sensor 116 is larger than the larger threshold value, and the room temperature when the output of the temperature sensor 116 is between the two threshold values. The control unit 201 uses the output of the temperature sensor 116 to set the linear velocity of the developing roller 104a in three stages, that is, when the temperature sensor 116 detects a low temperature, the speed is high, when it is a normal temperature, it is medium speed, and when it is a high temperature, it is low speed. The linear velocity of the developing roller 104a is switched.

As described above, by changing the linear velocity of the developing roller 104a according to the change of the environmental temperature, it is possible to suppress the change of the ID due to the change of the environmental temperature and the deterioration of the image quality. The linear velocity control by the ambient temperature is performed by the control unit 201 to the developing motor driver 205 by S
This is performed by outputting a 2-bit control signal composed of S3 and S4. FIG. 6 shows this control signal and the developing roller 10.
The relationship of the linear velocity of 4a is shown.

Next, the developing roller 104 according to the toner density
The linear velocity control of a will be described. This control is performed by the developing unit 1
This is to suppress the fluctuation of the ID caused by the fluctuation of the toner amount transferred to the photoconductor 101 due to the fluctuation of the toner density in 04. The toner sensor 117 uses a piezoelectric element, and the toner concentration is detected by the time interval during which toner is present on the vibration plate of the piezoelectric element.

Also in this control, two thresholds are set for the time interval detected by the toner sensor 117, similarly to the linear velocity control of the developing roller 104a by the environmental temperature described above.
As a result, the linear velocity of the developing roller 104a is switched. That is, when the time interval detected by the toner sensor 117 is smaller than the smaller threshold value (when the toner density is high), the speed is low, and when the time interval detected by the toner sensor 117 is larger than the larger threshold value. The mode is switched to high speed (when the toner density is low) and to medium speed when the time interval detected by the toner sensor 117 is between two threshold values (when the toner density is normal). The control unit 201 switches the linear velocity of the developing roller 104a by outputting a 2-bit control signal consisting of S5 and S6 to the developing roller driver 205 according to the time interval detected by the toner sensor 117. FIG. 7 shows the relationship between this control signal and the linear velocity of the developing roller 104a.

As described above, the linear velocity of the developing roller 104a is switched to high speed when the toner density is low, medium speed when the toner density is normal, and low speed when the toner density is high. It is possible to suppress the fluctuation of the ID due to the fluctuation and to suppress the deterioration of the image quality.

Next, the developing roller 1 depending on the usage status of the apparatus.
The linear velocity control of 04a will be described. In addition to the ambient temperature, the characteristics of the photoconductor are varied depending on the number of consecutive image formations, the idle time of the photoconductor 101, and other usage conditions of the apparatus. Therefore, like the above-described linear velocity control of the developing roller 104a based on the environmental temperature, the linear velocity of the developing roller 104a is set in advance according to the usage status of these devices, and the linear velocity is switched to suppress the fluctuation of the ID. ，
It is possible to suppress deterioration of image quality.

In this embodiment, the photosensitive member and the developing roller are driven by using separate motors, but the photosensitive member and the developing roller may be driven by using a single motor. For example, the linear velocity of the developing roller can be switched by interposing a gear with a clutch between the motor and the developing roller. Further, although the various linear velocity controls described above are also effective individually, it is desirable to combine the various linear velocity controls so that they can be handled with versatility.

Further, the image forming apparatus according to the present embodiment uses a two-component developer and reversal developing method,
There are many types of developers, developing systems, photosensitive members, etc., and image forming apparatuses use these in combination.
Therefore, the present invention needs to be applied in consideration of these types and combinations used in the image forming apparatus.

The image formed on the recording paper may not be entirely formed on the recording paper, for example, the image may be formed only on the upper portion of the recording paper. In an image forming apparatus that writes an image on a photoconductor using a laser light source,
In many cases, image data for driving the laser light source is temporarily stored in a memory or the like, and the area of the image formed on the recording paper can be easily determined from the image data stored in the memory. Therefore, based on the area of the image formed on each recording paper, for example, when the developing process for the image formed on the recording paper is completed, the linear speed of the developing roller is switched to a low speed so that the linear speed of the developing roller is changed. The speed can also be controlled.

[0038]

As described above, according to the present invention, a photoconductor on which an electrostatic latent image is formed according to an original image, and a developing roller for visualizing the electrostatic latent image formed on the photoconductor. The image forming apparatus including the control means for controlling the rotation speed of the developing roller on the basis of the image area / non-image area of the photoconductor is provided, so that the toner scattering amount from the developing roller is reduced, so The maintenance interval can be extended to reduce the maintenance cost and the running cost.

Further, as described above, the image forming apparatus according to the present invention is dependent on the usage status of the apparatus such as the toner remaining amount in the developing portion, the environmental temperature, the number of times of continuous image formation, and the photoconductor down time. Since the linear velocity of the developing roller is changed based on the above, it is possible to suppress the fluctuation of the image density and the deterioration of the image quality.

[Brief description of drawings]

FIG. 1 is a sectional view showing a schematic configuration of an image forming apparatus according to the present invention.

FIG. 2 is a block diagram showing a schematic configuration of a control system of the image forming apparatus according to the present invention.

FIG. 3 is a timing chart showing an example of a linear velocity control operation during an image forming operation according to the present invention.

FIG. 4 is an explanatory diagram showing a relationship between an environmental temperature according to the present invention and a linear velocity of a developing roller which is switched depending on the environmental temperature.

FIG. 5 is a table showing the relationship between control signals (S1, S2) and the linear velocity of the developing roller.

FIG. 6 is a table showing the relationship between control signals (S3, S4) and the linear velocity of the developing roller.

FIG. 7 is a table showing the relationship between control signals (S5, S6) and the linear velocity of the developing roller.

[Explanation of symbols]

101 photoconductor 104 developing unit 104a developing roller 116 temperature sensor 117 toner sensor 201 control unit 202 main motor 203 main motor driver 204 developing motor 205 developing motor driver

Claims (4)

[Claims] 1. An image forming apparatus comprising: a photoconductor that forms an electrostatic latent image according to a document image; and a developing roller that visualizes the electrostatic latent image formed on the photoconductor. An image forming apparatus comprising: a control unit that controls a rotation speed of the developing roller based on an image area / non-image area of a photoconductor. 2. A photoconductor that forms an electrostatic latent image according to an original image, a developing roller that visualizes the electrostatic latent image formed on the photoconductor, and a toner residual that detects a toner residual amount. An image forming apparatus comprising an amount detecting means, comprising: a controlling means for controlling a rotation speed of the developing roller based on a detection result of the remaining toner amount detecting means. 3. A photosensitive member that forms an electrostatic latent image according to an original image, a developing roller that visualizes the electrostatic latent image formed on the photosensitive member, and a temperature near the photosensitive member. An image forming apparatus having a temperature detecting means for controlling the rotation speed of the developing roller based on the detection result of the temperature detecting means. 4. An image forming apparatus comprising: a photoconductor that forms an electrostatic latent image according to a document image; and a developing roller that visualizes the electrostatic latent image formed on the photoconductor. An image comprising a control means for controlling the rotation speed of the developing roller based on the number of times image formation is continuously performed on the photoconductor, the idle time of the photoconductor, and other usage conditions of the device. Forming equipment.