JP2596007B2 - Developing device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a developing device used for an electrophotographic copying machine or the like.

[Prior Art] Conventionally, there is the following electrophotographic copying machine. That is, an image of a document is exposed on a photosensitive drum to form an electrostatic latent image, and the electrostatic latent image is developed by a developing device to form a toner image. The toner image is transferred and fixed on a transfer sheet to obtain a copy image. By the way, as the manuscript, A
Since there are various sizes such as 3, A4, B4 and B5 sizes, transfer paper for copying the image is also prepared in various sizes according to the size of the document. For this reason, a developing device that develops an electrostatic latent image corresponding to an image on a document is set to a size capable of developing the largest size latent image on the document, and the electrostatic latent image formed on the photosensitive drum is Areas other than the image are uniformly exposed to develop only an electrostatic latent image of a predetermined size.

The developing device is supplied with toner from a toner supply device via a toner supply device. The toner supply device uniformly supplies the toner according to the maximum size that the developing device can develop. Supply.

[Problems to be solved by the invention] However, such a conventional technique has the following problems. That is, the developing device is configured such that the toner is uniformly supplied to the area of the maximum developable size, for example, A3 size, whereas the image to be copied is A4 for A4 or A4 for B5 by the user. Most of them are B5 or some fixed size copy. Therefore, as for the toner in the developing device, only the toner in the area corresponding to the frequently copied size is consumed, and the toner in other areas is hardly consumed. Therefore, when an image having a size larger than a frequently used size is copied, a large amount of toner is consumed in an area corresponding to the size of the normally copied image, so that a density unevenness occurs in the copied image in the width direction. There was a problem.
This problem is particularly remarkable in a developing device in which the mixing of the developer in the axial direction of the photosensitive drum is poor.

[Means for Solving the Problems] Accordingly, the present invention has been made to solve the above-mentioned problems of the prior art, and the purpose of the present invention is to use a toner in a frequently used size portion. An object of the present invention is to provide a developing device that does not cause density unevenness in a copied image even when an image of a size that is hardly used is copied by supplying a large amount of the image.

That is, the present invention provides a developing device in which a latent image formed on an image carrier is developed with toner, and toner consumed during development of the latent image is supplied by the toner supply unit. A cylindrical member provided inside the developing device corresponding to substantially the entire developing area thereof and for supplying toner from the outside into the developing device; and a cylindrical member provided inside the cylindrical member and having a shaft. And a transport member for transporting the toner along the direction.
A toner supply port whose opening width is changed so as to supply the toner in accordance with the development frequency of the region to be developed is provided along the longitudinal direction.

As a developing device to which the present invention is applied, for example, a two-component developing device using a developer composed of a toner and a carrier is used. However, the developing device is not limited thereto. In the case of a system-based developing device, unevenness in image density due to bias of the toner layer is less likely to occur than in a two-component system developing device, but is sufficiently applicable.

As the toner supply means, for example, an auger pipe and an auger rotatably provided therein, which is configured to supply toner into the developing device from a supply port provided in the auger pipe is used. However, the present invention is not limited to this, and any device that can supply toner into the developing device may be used.

Further, as the toner supply means, for example, a toner supply means which supplies a large amount of toner to an A4 size area by presetting an opening width and an angle of a supply port provided in an auger pipe is used. However, the present invention is not limited to this. For example, a large amount of toner is supplied to a B5 size area.
The setting is made arbitrarily.

Further, the position of the latent image to be developed differs depending on which position the original is placed on the platen glass. For example, in the case of a so-called corner registration type copying machine in which a document is placed with reference to a corner of a platen glass, a latent image is formed on one end side of the image carrier, so that toner supplied by toner The amount is also set based on one end. Conversely, in the case of a so-called center registration type copying machine in which a document is placed with reference to the center of the platen glass, a latent image is formed on the image carrier at the center thereof, and is supplied by toner supply means. The amount of toner is also set based on the center.

Further, a region where a large amount of toner is supplied by the toner supply unit may be adjusted as needed. For example,
The opening width, angle, and the like of the supply port provided in the auger pipe may be made variable by a slit, a motor, or the like.

[Operation] In the present invention, the toner supply unit supplies the toner according to the development frequency of the area to be developed, so that a large amount of toner is supplied to the area that is frequently developed, and the toner is supplied to the area that is hardly developed. Is supplied only in a small amount, and even when an image of a size that is rarely used is developed, the density unevenness does not occur.

[Embodiments] The present invention will be described below based on the illustrated embodiments.

FIG. 17 shows an electrophotographic copying machine to which the toner supply device according to the present invention can be applied. This copying machine, in addition to normal copying, double-sided copying, single-sided multiplex copying, and marking for partially marking a copy image in a different color, for example, at a low density to emphasize a portion of the copy image It is a copying machine with a composite function that can perform copying such as color copying. In addition, since the paper feed cassettes that supply paper are all housed inside the copier, the paper feed cassette does not protrude to the outside, so the installation space can be reduced and the appearance can be reduced. It has a clean and nice looking configuration.

The copying operation in the copying machine is performed as follows. That is, the original 2 placed on the platen glass 1 is illuminated by the light source 3, and the reflected light image from the original 2 is reflected by the photoconductor via the mirrors 4, 5, 6, 7, 8, 9 and the lens 10. Scanning exposure is performed on the drum 11. The copying machine is of a corner resist type in which the original 2 is placed with the corner of the platen glass 1 as a reference. After the photosensitive drum 11 is uniformly charged in advance by the charger 12, the image of the original 2 is exposed as described above, and an electrostatic latent image is formed on the photosensitive drum 1. 2 is mounted on the basis of the corner of the platen glass 1 as described above, so that an electrostatic latent image is also formed on one end of the photosensitive drum 11. This electrostatic latent image is developed by the selectively operating main developing device 13 or auxiliary developing device 14 to become a toner image. In the main developing device 13, black toner is used,
Normal image development is performed, and in the auxiliary developing device 14, a color toner such as red or blue is used, and is mainly used for developing only a predetermined image when performing marking color copying or the like. .

The toner image developed by the developing device 13 or 14 is transferred onto a transfer sheet 20 of a predetermined size supplied from one of a plurality of paper feed cassettes 15, 16, 17, 18, and 19.
The transfer is performed by charging the transfer corotron 21. The transfer paper 20 on which the toner image has been transferred is separated from the photosensitive drum 11 by charging of the separation control unit 22, and then the fixing unit 23
, And the toner image is fixed on the transfer paper 20.
The transfer paper 20 on which the toner image is fixed is discharged onto the discharge tray 24 as it is in a normal copy mode.

This copier is provided with the paper cassettes 15, 16, 17,
In addition to having a plurality of sheets 18 and 19, each sheet cassette accommodates transfer papers 20 having different sizes such as A3, A4, B4, and B5, and the user selects a desired cassette and selects an arbitrary one. A copy image of a size can be obtained. However, it is extremely rare for users to copy images of each size evenly, and usually the size of frequently copied images is A4 size for A4 size, B5 size for B5 size, etc. I have decided.

In the above-described modes such as double-sided copying, single-sided multiplex copying, and marking color copying, the transfer paper 20 on which the toner image has been fixed is not discharged as it is, but is transferred as it is or is The sheet is turned over and transported again to the image forming section, where a predetermined toner image is transferred. After the transfer and fixing of the predetermined image are repeated, the transfer paper 20 is discharged onto the discharge tray 24 for the first time.

In this embodiment, in addition to the main developing device 13, an auxiliary developing device 14 that uses toner having a different color from the main developing device 13 is provided inside the copying machine main body. Most of the processing is performed by the main developing device 13.

1 and 2 show the main developing device as one embodiment of the developing device according to the present invention. In the figure, reference numeral 27 denotes a developing device main body.
And the like, is formed in a box shape having a substantially U-shaped cross section, and an opening 28 is provided on the photosensitive drum 11 side. The bottom and side surfaces inside the developing device main body 27 are covered with a thin metal plate 29, thereby preventing the developing device main body 27 from being unintentionally charged by the developer 30. A toner supply unit 31 for supplying a toner T from a toner supply unit described later is provided substantially at the upper center of the developing device main body 27.
Is composed of a cylindrical auger pipe 32 and an auger 33 rotatably disposed therein. As shown in FIG. 7, the auger pipe 32 is provided with a supply port 34 for supplying toner to the rear inside the developing device main body 27 along the longitudinal direction. As shown in FIG. 13, it is provided outside the developing device main body 27.

The toner supplied into the developing device main body 27 as described above is
The developer is guided to a mixer 36 rotatably provided at the rear portion of the developing device main body 27 by the partition plate 35, and is agitated with the carrier by the mixer 36 to become the developer 30. The above partition plate 35
As shown in FIGS. 3 and 4, the upper end is fitted on the outer periphery of the auger pipe 32 via a curved portion 35a curved in an arc shape at the upper end thereof, and is attached to both ends of the partition plate 35. Is
As shown in FIG. 4, a contact piece 35b is protruded from the side. As shown in FIG. 4, the contact piece 35b is in contact with a part of a metal plate 29 coated on the bottom surface and side surfaces in the developing device main body 27, and the metal plate 29 is separated from the partition plate 35 and the auger pipe. Connected to ground via 32. Then, the developing device main body 27 is configured to release the charged electric charge via the metal plate 29, thereby preventing the developing device main body 27 from being unintentionally charged. When the metal plate 29 is connected to the ground via the partition plate 35 and the auger pipe 32 as described above, compared to the case where the metal plate 29 and the auger pipe 32 are separately connected to the ground as in the related art, The wiring for connecting to the ground can be simplified, and the cost can be reduced.

As shown in FIG. 1, the mixer 36 connects a plurality of flat plates 37, 37,... Formed in a polygonal shape in a state of being inclined in parallel with each other, and is rotationally driven by shaft portions 38 provided at both ends thereof. By doing so, the toner is stirred by sliding on the inclined flat plates 37, 37... Together with the developer 30.

The developer 30 agitated by the mixer 36 is sent to a paddle 39 having a plurality of blades radially through a passage below the partition plate 35, and further conveyed to a developing roll 40 while being agitated by the paddle 39. And the developer 30 is
While being attracted to the magnet roll 41 provided inside the developing roll 40, it moves with the rotation of the developing roll 40. A developing bias voltage is applied to the developing roll 40. In this embodiment, a developing bias is applied to the developing roll 40 via the magnet roll 41. The thickness of the developer 30 is regulated by a trimmer bar 42 provided on the ceiling portion of the apparatus main body 27, so that the developer 30 adheres to the surface of the developing roll 40 in a uniform thickness. A predetermined voltage is applied to 42 in order to improve the breaking of the ears of the developer 30 to prevent fog and the like.

That is, as shown in FIG. 5, a bias voltage is applied to one end of the trimmer bar 42 from a connector 43 fixed to the developing device main body 27 on the same end via a short harness wire 44. I have. At the other end of the trimmer bar 42, a plate 45 for fixing one end of the non-rotating magnet roll 41 is fixed.
, A bias voltage is applied through the plate 45. In such a case, there is no need to apply a developing bias to the shaft of the non-rotating magnet roll via a long harness wire from the connector as in the related art, so that the configuration can be simplified. Thus, a predetermined bias voltage is applied to the magnet roll 41 from the connector 43 via the harness wire 44, the trimmer bar 42, and the plate 45. As described above, the developer 30 is transported to the surface of the developing roll 40 close to the photosensitive drum 11, and develops the electrostatic latent image formed on the surface of the photosensitive drum 11 with a predetermined developing bias. ing.

In this embodiment, as shown in FIG. 6, the width of the mixer 36 is set to be larger than the maximum width E of the transfer paper 20 on which copying is possible, and the widths of the paddle 39 and the developing roll 40 are accordingly set. Are also set to the same width as the mixer 36. In such a case, if the width of the mixer 36 is equal to the width of the maximum transfer paper as in the related art, the toner and the developer are not sufficiently mixed and stirred at both ends of the mixer, and the image is transferred to the maximum width of the transfer paper. In such a case, density unevenness may occur at both ends, but since the width of the mixer 36 is larger than the maximum width of the transfer paper, the toner and the developing agent are not applied to the portions corresponding to both ends of the maximum width of the transfer paper. The stirring with the agent is sufficiently performed, and the occurrence of density unevenness can be prevented.

By the way, in the developing device according to this embodiment, the toner supply means is configured to supply the toner in accordance with the development frequency of the area to be developed. That is, the developing device body
The supply port 34 is provided along the longitudinal direction of the auger pipe 32 for supplying the toner into the inside 27 as shown in FIGS. 7 and 8 to 11. The copying apparatus is set to supply a large amount of toner to a region R corresponding to a size where copying is frequently performed, for example, an A4 size. The upper end 34a of the supply port 34 is located horizontally in the center of the auger pipe 32 as shown in FIG. 7, while the lower end 34b is gradually inclined downward from the supply end 34c. It is provided to be. Further, the end portion 34d of the supply port 34 is opened over the entire lower half of the auger pipe 32 as shown in FIG. 46 is auger pipe 32
As shown in FIG. 11, an opening is provided at the end of the lower part over the entire lower half thereof. This opening 46 drops all the toner not supplied from the supply port 34 and is conveyed by the auger 33. Toner is prevented from entering the bearing that rotatably supports the auger 33.

The supply port 34 has an opening width so as to supply a large amount of toner to an area corresponding to the width W of the A4 size, which is frequently copied based on the end portion 34d, and to supply a small amount of toner to other areas. Is set. In the drawing, reference numeral 47 denotes a developer collecting port opened at the base end of the auger pipe 32 as shown in FIG. 8, for collecting the developer 30 collected by the developer collecting plate 48. is there.

FIG. 12 shows a toner supply device for supplying toner to the developing device. This toner supply device 49 has a thirteenth
As shown in the figure, the toner supply device 49 is provided on one side of the main developing device 13 so that the upper end thereof is provided at a height positioned to the side of the auxiliary developing device. The shaft 50 enables rotation in a horizontal plane. When supplying toner to the toner supply device 49, the door (not shown) provided on the front of the copying machine is opened to expose the toner supply device 49, and the toner supply device 49 is connected to the rotating shaft 50. It is rotated 90 degrees as the center to supply toner.

In the figure, reference numeral 51 denotes a toner supply device main body, and the inside thereof is a toner storage section 52 for storing the toner T. At the upper end of the toner supply device main body 51, a replenishing port 53 for replenishing the toner in the toner container 52 is provided, and the replenishing port 53 is tiltable. That is, the supply port member 54 is, as shown in FIGS. 14 and 15,
An upper plate 55 having a supply port 53, fan-shaped side plates 56, 56 provided at both ends thereof, and arcuate side plates 57 provided on side surfaces of the both plates 56, 56 are formed. The replenishing port member 54 is rotatably attached to a mounting port 59 of the toner supply device main body 51 via a shaft portion 58 provided at the center of the fan-shaped side plates 56, 56. A cap (not shown) is attached to the supply port 53. In the drawing, reference numeral 60 denotes a stopper for preventing the supply port member 54 from coming off.

To replenish the toner to the toner supply device 49, the replenishing port member 54 is rotated about the shaft 58, the replenishing port 53 is inclined, and the replenishing port 53 is removed by removing a cap (not shown). Open. And the inclined supply port 53
Then, as shown in FIG. 15, the toner T is supplied from the bolt 61. In this manner, by making the supply port 53 tiltable, the supply port 53 can be easily inserted into the supply port 53 as compared with a conventional case where a supply port is provided horizontally at the upper end of the toner supply device as shown in FIG. The toner can be replenished and toner spillage can be prevented.

Further, the toner T contained in the toner container 52 is agitated at a predetermined timing so that the toner T
A coil-shaped agitator 63 is rotatably provided as a stirring means for preventing blocking or the like.

As shown in FIG. 12, a cylindrical guide 64 having a U-shaped cross section is provided at the bottom of the toner supply device main body 51. The toner T is provided inside the cylindrical guide 64. An auger 65 to be conveyed is provided rotatably. The toner T conveyed by the auger 65 is supplied into an opening 67 of the auger pipe 32 protruding outside the main developing device 13 through a supply port 66 provided on the bottom surface of the cylindrical guide portion 64. It has become. The toner T supplied into the opening 67 of the auger pipe 32 is supplied to the auger 33 provided in the auger pipe 32.
Is conveyed into the main developing device 13 as described above.

In the configuration described above, the developing device according to this embodiment supplies toner as follows. That is, in the electrophotographic copying machine, the original 2 is placed on the platen glass 1.
And an image of the document 2 is scanned and exposed on the photosensitive drum 11 to form an electrostatic latent image. This electrostatic latent image is developed by a developing device.
Done by At this time, A3, A
Although various sizes such as 4, B4, and B5 sizes are used, the size of the original 2 to be copied is
However, it is almost constant for each user, such as most users and B5 for some users, and other sizes are rarely copied. Therefore, as for the toner in the main developing device 13, only the toner in the frequently copied area is consumed, and the toner in the other areas is hardly consumed. This trend is constant for each user.

By the way, in the developing device according to this embodiment, since a large amount of toner is supplied to an area corresponding to the A4 size, even if the A4 size original is frequently copied,
There is no shortage of toner in the corresponding area. Therefore, even when a document of a size larger than the frequently-copied size (A4 size), such as the A3 size, is occasionally copied, the main developing device 13 contains toner of all sizes. Thus, an image can be copied without causing density unevenness in the width direction of the main developing device 13.

As described above, the auger pipe 32 that supplies the toner into the main developing device 13 is provided with the supply port 34 that supplies a large amount of the toner to the area corresponding to the A4 size image. Even in a user who performs copying of the original 2, the toner in the area corresponding to the A4 size does not decrease, and even when the original 2 of the A3 size or the like is copied, the original 2 can be copied without causing the density unevenness. .

[Effects of the Invention] The present invention has the above-described configuration and operation. A toner supply unit is provided inside the developing device so as to correspond to substantially the entire developing area, and toner is supplied from the outside to the developing device. A cylindrical member for supplying, and a conveying member disposed inside the cylindrical member and conveying the toner along an axial direction of the cylindrical member. By providing a toner supply port whose opening width is changed so as to supply toner in accordance with the longitudinal direction, a large amount of toner is supplied to a frequently used size portion, Even when an image of a size that is hardly used is copied or the like, it is possible to prevent unevenness in the density of development from occurring in the image.

In addition, the present invention corrects the bias of toner consumption due to various factors by making the opening width of the toner supply port of the cylindrical member constituting the toner supply unit variable, and develops the image into an image. Can be prevented from occurring.

[Brief description of the drawings]

FIG. 1 is a perspective view of an essential part showing one embodiment of a developing device according to the present invention, FIG. 2 is a longitudinal sectional view showing the developing device, FIG. 3 is a sectional view showing a mounting portion of a partition plate, FIG. FIG. 5 is a front view showing the mounting portion, FIG. 5 is a perspective view of the developing device with a part removed,
6 is an explanatory plan view of the developing device, FIG. 7 is a front view showing the toner supply means, FIG. 8 is a sectional view taken along line AA of FIG. 7, and FIG. 9 is a line BB of FIG. FIG. 10 is a sectional view of FIG.
FIG. 11 is a sectional view taken along line DD of FIG. 7, FIG. 12 is a sectional view showing the toner supply device, and FIG. 13 is an explanatory diagram showing the positional relationship between the toner supply device and the developing device. FIG. 14 is a perspective view of the toner supply device, FIG. 15 is a longitudinal sectional view of the toner supply device, FIG. 16 is a cross-sectional view showing a conventional toner supply device,
FIG. 17 is a configuration diagram showing an electrophotographic copying machine to which the developing device according to the present invention can be applied. [Explanation of Symbols] 11 photoconductor drum 31 toner supply means 32 auger pipe 33 auger 34 supply port T toner

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Nagakazu Okegawa 2274 Hongo, Ebina-shi, Kanagawa Prefecture Fuji Xerox Co., Ltd.

Claims (2)

(57) [Claims] A developing device for developing the latent image formed on the image carrier with toner, and supplying toner consumed by the development of the latent image by the toner supplying device; A cylindrical member provided inside the developing device corresponding to substantially the entire development area thereof, for supplying toner from the outside into the developing device; and a cylindrical member provided inside the cylindrical member and having an axial direction. The cylindrical member is provided with a toner supply port whose opening width is changed so as to supply the toner in accordance with the development frequency of the development area, in the longitudinal direction thereof. A developing device characterized in that the developing device is provided along. 2. The developing device according to claim 1, wherein an opening width of a toner supply port provided in said cylindrical member is variable.