JPH1069189A - Image forming device - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To form a solid black image on a transfer paper to reduce the toner density in a developing device, prevent toner from being scattered during transportation, and also have a problem of toner individualization during transportation and storage. Another object of the present invention is to provide an image forming apparatus which does not require a dedicated service person for setup. In an image forming apparatus that forms an image using a two-component developer composed of a toner and a carrier, a photoconductor 1 on which an electrostatic latent image is formed by exposure and an electrostatic latent image on the photoconductor 1 A developing device 2 for supplying toner;
A transfer device 3 for transferring the toner image formed thereon onto transfer paper; a density detecting means 4 for detecting the toner density in the developing device 2; The formed toner image is transferred to transfer paper by the transfer device 3, the toner density value in the developing device 2 is reduced, and the above-described exposure, development, and transfer operations are performed until the toner density value becomes a predetermined value or less. Is provided repeatedly.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electrophotographic copying machine,
The present invention relates to an image forming apparatus such as a laser printer and a facsimile, and more particularly to an image forming apparatus that forms an image by developing an electrostatic latent image on a photoconductor using a two-component developer including a toner and a carrier.

[0002]

2. Description of the Related Art In an image forming apparatus for forming an image by developing an electrostatic latent image on a photoreceptor using a two-component developer composed of a toner and a carrier, a developing device for accommodating a toner and a carrier is a main body of the apparatus. When the developer is transported while being stored in the printer, or when the developer containing the two-component developer is removed from the apparatus main body and transported, there is a possibility that the apparatus main body and the periphery of the developing apparatus may be stained by scattering of toner due to vibration. However, recently, in order to simplify the transportation, there are many methods of transporting the developing device with the developing device stored in the main body of the device. For this reason, a partition is provided in the developing device so that a carrier is stored below the developing device and a toner is stored above the developing device (Japanese Patent Laid-Open No. 2-93483), or a developer leakage prevention member or a film sheet is used. According to a method of covering the outlet portion of the developing device (Japanese Utility Model Laid-Open No. 63-138561),
It is designed so that toner does not scatter during transportation.

[0003]

However, according to the above-mentioned conventional technology, a service person dedicated to removing a partition in a developing device at a transportation destination, and removing and setting up a developer leakage prevention member and a film sheet, etc., is required. It was inconvenient because it required it. Furthermore, it is not easy to move the apparatus body at the destination after the setup is completed once. In addition, since the developer containing the toner is contained, there is a problem that the toner is individualized due to a rise in temperature during transportation or storage. Therefore, the present invention
By forming a solid black image on the transfer paper, the toner concentration in the developing device is reduced at a stretch, preventing the toner from being scattered during transportation, without the problem of toner individualization during transportation and storage,
Another object of the present invention is to provide an image forming apparatus that does not require a dedicated service person for setup.

[0004]

According to a first aspect of the present invention, there is provided an image forming apparatus for forming an image using a two-component developer comprising a toner and a carrier. A photoreceptor on which an image is formed, a developing device for supplying toner to the electrostatic latent image on the photoreceptor, a transfer device for transferring the toner image formed on the photoreceptor to transfer paper, and the developing device Density detecting means for detecting the toner density in the photoconductor, and exposing the photoreceptor to transfer the toner image formed by the developing device onto transfer paper by the transfer device. This is achieved by providing an image forming apparatus having a density control unit that repeats the above-described exposure, development, and transfer operations until the toner density value falls below a predetermined value. In order to achieve the second aspect, in addition to the image forming apparatus for achieving the first aspect, the density control means may stop the repeated operation of the exposure, development, and transfer operations. The determined toner density value is attained by the image forming apparatus when the toner density value detected by the density detecting means is saturated.

[0005]

According to the first aspect of the present invention, the entire surface of the photoreceptor is exposed by the density control means, and a solid black toner image is formed by supplying the toner from the developing device. Can be controlled to transfer the solid black toner image formed on the transfer paper, so that the exposure, development and transfer operations are repeated, so that the toner density in the developing device decreases, and a predetermined toner density value is reduced. When the density detecting means detects, the density control means can stop the repetitive operation. According to a second aspect of the present invention, in addition to the image forming apparatus of the first aspect,
When the density detecting means detects that the toner density value is saturated, the density control means stops the above-described repetitive operations of exposure, development and transfer, so that the developing device can be made to have almost no toner. .

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is a front vertical sectional view showing a main part of an electrophotographic copying machine as an image forming apparatus. Since the detailed configuration and functions of the copying machine are known, only an outline will be given. The reading optical system 20 includes a light source 21 for irradiating the original on the contact glass CG with light,
A mirror group 23 for guiding the reflected light to the condenser lens 22 and an image reading element 24 for reading the collected reflected light
And a reading unit fan 25 for radiating heat generated from the light source 21 to the outside. The writing optical system 30 reflects light from a light-emitting light source (not shown) on a polygon mirror 31 that is timed, condenses it on a lens group 32, reflects it on a mirror 33 in a predetermined direction, The electrostatic latent image is guided to the surface of the photoreceptor 1 charged by 34 to match the read image. This electrostatic latent image is visualized by toner carried by the developing sleeve 2a of the developing device 2. On the other hand, one of the transfer papers in the paper feed cassette 35 is fed to a predetermined position (transfer position) of the photoconductor 1 by the paper feed roller 36, and is moved in synchronization with the rotation of the photoconductor 1 (in the direction of the arrow). After the toner image visualized by the operation of the transfer charger 3a of the transfer device 3 is transferred to the transfer paper, the charge given to the transfer paper by the separation charger 3b is removed, and the transfer paper is removed from the photosensitive member 1. The toner image is thermally fixed on the transfer paper by the thermal fixing device 37. After the transfer of the toner image onto the transfer paper, the toner remaining on the surface of the photosensitive member 1 is removed by the cleaning unit 38, and the next photosensitive and electrostatic latent image is formed.

FIG. 2 is a diagram for mainly explaining the operation of the photosensitive member 1 and the developing device 2. Light from a light-emitting source of the writing optical system 30 (not shown) is supplied to a mirror 33 in the final process.
Is reflected in the direction of the photoreceptor 1 to expose the surface of the photoreceptor 1 and rotate in the direction of arrow (A) to form an electrostatic latent image. The developing device 2 includes a toner cartridge 2e.
Is dropped downward with the rotation of the toner supply roller 2d, and adheres to the carrier by being stirred by the stirring screw 2c. The carrier with the toner attached thereto is extruded in the direction of the developing sleeve 2a by the stirring screw 2c. Since the developing sleeve 2a holds the magnet roller 2b inside, it attracts the carrier with the toner adhered to the surface of the developing sleeve 2a. The doctor blade 2f scrapes the carrier so that the carrier to which the toner is attached is uniformly distributed on the surface of the developing sleeve 2a.

As the developing sleeve 2a rotates counterclockwise, the toner adhering to the surface of the developing sleeve 2a is applied to the electrostatic latent image on the surface of the photoconductor 1 at the narrowest portion between the developing sleeve 2a and the surface. The electrostatic latent image is attracted and replaced with a visible toner image. Further, the registration roller 38 starts rotating in synchronization with the rotation of the photoconductor 1, the transfer paper P is fed in the direction of the arrow (A), and the toner image on the surface of the photoconductor 1 is transferred by the transfer charger 3a of the transfer device 3. The transfer paper P is transferred onto the paper P, and the charge given to the transfer paper P by the separation charger 3b is discharged, and the transfer paper P is separated from the photoreceptor 1. On the other hand, when the carrier on the developing sleeve 2a that has supplied the toner to the photoreceptor 1 moves near the stirring screw 2c, the carrier replaces the carrier to which the toner is newly attached or reattaches the toner. Every time the above-described operation of the developing sleeve 2a is repeated, the amount of the entire toner decreases. Therefore, by detecting the state of the carrier to which the toner falling along the upper surface of the separator 2g is attached by the density detecting element 4, the toner density can be known. In the copy operation state, when the toner density becomes lower than a certain value, the toner supply roller 2d is rotated to supply the toner so that the toner density in the apparatus becomes higher than a specified value.

Therefore, if the apparatus main body is transported to another place while the toner concentration is maintained at a specified value or more as described above, the toner spills out of the gap between the developing device 2 and the photoreceptor 1, and the image The toner scatters in the forming apparatus, and stains each part. Therefore, in the present invention, the toner in the developing device 2 is reduced so that there is almost no toner, so that the toner does not spill out from the gap between the developing device 2 and the photoconductor 1. Further, as described above, the surface of the photoconductor 1 is exposed to form an electrostatic latent image, and the developing device 2 replaces the electrostatic latent image on the surface of the photoconductor 1 with a visualized toner image. , The amount of toner in the developing device 2 decreases. At this time, if the toner cartridge 2c is removed in advance, the toner supply is prevented, so that the amount of toner is further reduced. In the present invention, the density control unit 5 controls the exposure, development, and transfer operations, and when the toner density detected by the density detection element 4 falls below a certain value, a series of operations is stopped. Further, when the surface of the photoconductor 1 is exposed, if the entire surface is exposed to form a solid black image, the toner density can be rapidly reduced.

FIG. 3 is a diagram for explaining how the density detecting element 4 detects the toner density. In order to make the explanation easy to understand, the rotation direction of the developing sleeve 2a and the position of the doctor blade 2f are different from those in FIG. Therefore, the carrier on the developing sleeve 2a is scraped off by the doctor blade 2f, and a part of the carrier passes between the density detecting elements 4. The density detecting element 4 shown here is generally called an F sensor, and a coil 4b is attached to a bobbin 4a.
Is wound, and when the toner concentration of the developer passing through the bobbin 4a changes, it appears as a change in the amount of carrier, and the self-inductance of the coil 4b wound on the bobbin 4a changes. . Therefore, the toner density can be known by detecting the amount of change in the self-inductance. Although not shown, a P sensor pattern is formed on the surface of the photoreceptor 1, a toner image is formed by the developing device 2, and the density is detected by a density detecting element called a P sensor. Can also be detected. Regarding the present invention, the detection of the toner concentration in the developing device 2 may be performed by the above-described method, another method, or any method.

FIG. 4 is a diagram showing a state in which the state of the copying operation is shifted (period 1) to the operation state of the density controller 5 (period 2). In the state during the copy operation (period 1),
In order to form an image on the transfer paper, the toner density is controlled near Tc, which is a high level, and when a decrease in the toner density is detected by the density detecting element 4, the toner is supplied by rotating the toner supply roller 2d. I do. In the period 1 of the copy operation, the above process is repeated. Next, when the process moves to preparation for shipment of the image forming apparatus (period 2), first, the toner cartridge 2e is removed from the image forming apparatus main body. Subsequently, the above-described exposure, development, and transfer operations are performed according to an instruction from the density control unit 5, and a solid black image is formed on the transfer paper until the toner density detected by the density detection element 4 becomes equal to or less than a predetermined value To. When the toner concentration To is detected, the series of operations described above is terminated, and the preparation for shipment of the developing device 2 is completed.
Experimentally, the toner density Tc in the copy operation state is:
Usually, it is about 2 to 3.5%, and the predetermined value To for ending the series of operations is usually about 0 to 0.5%, but differs depending on the type of the image forming apparatus. Further, in the operation for preparing the shipment of the image forming apparatus, when the density control unit 5 performs the above-described exposure, development, and transfer operations and the toner density detected by the density detection element 4 is saturated (Ts value), Is completed, and the preparation for shipment of the developing device 2 is completed (the invention of claim 2). That is, in the second aspect, the predetermined toner density value at which the density control means 5 stops the repetitive operation of the exposure, development, and transfer operations is the density value when the toner density value detected by the density detection means is saturated. It is characteristic that this is done. The toner density value Ts in FIG. 4 corresponds to this, and the scattering of the toner during transportation decreases as Ts approaches zero.

FIG. 5 is a flowchart showing the main operation of the density control unit 5 in the period 2. In the copy operation state (period 1), a toner cartridge provided with a two-component developer composed of a toner and a carrier is set in the developing device 2, and transfer paper is set in the paper supply unit 35 (step S).
1). In step S2, it is asked whether or not the operation is for shipment preparation (period 2) (S2). If it is not the operation for shipment preparation (period 2) (S2 No), an operation such as continuation of the copy operation through this flow is performed. Continue. Returning to step S2, if the operation is a preparation for shipment (period 2) (S2 Yes), the toner cartridge 2e is first removed from the image forming apparatus main body (S2).
3) The density control unit 5 is operated by pressing an operation key or the like on an operation unit (not shown) (S4). When the density control unit 5 operates, the entire surface of the photoconductor 1 is exposed to form a solid black image on the transfer paper (S5). The developing device 2 replaces the electrostatic latent image on the surface of the photoconductor 1 with a visualized toner image (S6), and the transfer device 3 transfers a solid black image to transfer paper (S7). Subsequently, the density detecting element 4
(S8-1) is determined whether the toner density detected by the printer becomes equal to or less than a predetermined constant value To. If the toner density is not lower than the fixed value To (S8-1 No), the process returns to step S5, and the exposure (S5), development (S6), and transfer (S7) operations are performed to reduce the toner density to the fixed value To or lower. Continue until it is. Returning to step S8-1, if the toner density detected by the density detecting element 4 becomes equal to or less than the predetermined constant value To (S8-1 Yes), a series of operations is terminated, and the preparation for shipment of the developing device 2 is completed. Is completed (S9).

FIG. 6 is a flow chart showing the main operation of the second aspect of the present invention. When the toner density detected by the density detecting element 4 has reached a saturated state (Ts value), a series of operations is completed, and preparation for shipment of the developing device 2 is completed. Here, the difference from the operation of FIG. 5 is that the toner density detected by the density detecting element 4 in FIG.
In FIG. 6, the toner density detected by the density detecting element 4 is saturated (T
(S value) (S8-2). Other parts are the same as those in FIG. 5, and further description is omitted.

[0014]

According to the first aspect of the present invention, the density control means repeatedly forms a solid black toner image on the transfer paper to reduce the toner density in the developing device at a stroke, and the density detection means is determined in advance. When the toner density value is detected, the transfer operation is stopped. Therefore, if the predetermined toner density value is set to a toner amount that does not cause the toner to be scattered during transportation, the density control means is activated. Accordingly, it is possible to provide an image forming apparatus that can easily prepare for shipment of the developing device.

According to a second aspect of the present invention, in addition to the image forming apparatus of the first aspect, when the density detecting means detects that the toner density value is saturated, the density controlling means transfers the transfer paper. Since the operation can be stopped to make it possible to make the toner hardly exist in the developing device, it is possible to prevent the toner from being scattered during transportation, and to have no trouble of toner singulation during transportation and storage, and Thus, it is possible to provide an image forming apparatus that does not require a dedicated service person for setup.

[Brief description of the drawings]

FIG. 1 is a side view of a main part of an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a side view of a main part around a developing device of the image forming apparatus according to the embodiment of the present invention.

FIG. 3 is an explanatory diagram illustrating an example of a density detection element that detects a toner density in a developing device.

FIG. 4 is an explanatory diagram for explaining an operation state of a density control unit according to the embodiment of the present invention.

FIG. 5 is a flowchart showing a main operation according to claim 1 of the present invention.

FIG. 6 is a flowchart showing a main operation according to claim 2 of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Photoconductor 2 Developing device 3 Transfer device 4 Density detection element or density detection means 5 Density control part or density control means

Claims (2)

[Claims] 1. An image forming apparatus for forming an image using a two-component developer comprising a toner and a carrier, wherein a photosensitive member on which an electrostatic latent image is formed by exposure and an electrostatic latent image on the photosensitive member are provided. A developing device that supplies toner, a transfer device that transfers a toner image formed on the photoconductor to transfer paper,
Density detecting means for detecting a toner density in the developing device, and a toner image formed by the developing device by exposing the photoreceptor, and transferring the toner image to transfer paper by the transfer device to thereby obtain a toner density value in the developing device. An image forming apparatus comprising: a density control unit that repeatedly performs exposure, development, and transfer operations until the toner density value falls below a predetermined value. 2. The image forming apparatus according to claim 1, wherein
The predetermined toner density value at which the density control means stops the repetition of the exposure, development, and transfer operations is a density value when the toner density value detected by the density detection means is saturated. Image forming device.