JPH06214455A - Development device - Google Patents

Abstract

(57) [Abstract] [Purpose] In a developing device of an image forming apparatus that develops an electrostatic latent image with toner and transfers it to a printing sheet, the terminal portion of the developing tank cartridge also serves as the positioning when the developing tank is attached. As a result, it is possible to reduce the size by removing the positioning space on both the developing tank cartridge and the main body side. [Structure] A rib 2 made of an insulating material is provided around a terminal 3 of a developing tank cartridge 1, a hole 6 for receiving the rib 2 is provided in a main body substrate side earth plate 5, and the developing tank cartridge 1 is positioned by the rib 2. As well as
The rib 2 prevents a short circuit between the terminal 3 of the developing tank cartridge 1 and the main body side ground plate 5. Further, the ground plate 5 is provided with a cut-and-raised shape 8, and the ground plate 5 is attached to the image forming apparatus 20 by a hooking method using spring elasticity.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a printer or a copying machine using electrophotographic technology, and
The present invention relates to a developing device having a developing tank cartridge replaceable by a user.

[0002]

2. Description of the Related Art In a developing device such as a laser printer or a copying machine, when the number of used sheets reaches a preset allowable number, a display is displayed on a display panel to urge replacement of a toner cartridge or a developing tank cartridge. There is.
This allowable number varies depending on the model, but is usually 10-2.
It is about 0,000 sheets. The user of the printer, the copying machine or the like replaces the toner cartridge or the developing tank cartridge containing toner with a new one according to the display on the display panel.

However, in the case of new toner immediately after replacement, since the charge amount is small, the apparent density is large and the volume is small, the output voltage of the toner sensor using the magnetic permeability sensor is temporarily increased. After that, as the magnet roller, the stirring roller, etc. rotate, the toner charge amount increases, the apparent density decreases, and the volume increases, so that the output voltage of the toner sensor decreases and the output becomes constant when saturated.

Therefore, if the developing device does not have a mechanism for detecting whether or not the toner is new (abbreviated as initial detection), the output voltage of the toner sensor is controlled so as to become the reference voltage. Toner is replenished when the voltage is high. Then, since the toner density rises, fogging becomes large, and the magnet roller of the developing device is rotationally driven until the output voltage of the toner sensor reaches the reference voltage, there is a problem that the warm-up time of the device becomes long. is there.

Therefore, the developing device is provided with a fuse for detecting whether or not the toner is new. As a result, when the main switch of the image forming apparatus is turned on, the conduction state of the fuse is inspected to determine the toner state.

If there is continuity in the inspection of this fuse,
When it is determined that the toner is new, the toner supply motor is turned off, and the magnet roller and the like are driven to rotate for 1 or 2 minutes. At this time, the number-of-uses counter for knowing the life of the toner is initialized. After that, the fuse is blown by applying a current that greatly exceeds the rated current of the fuse. On the other hand, if there is no conduction in the fuse inspection, it is determined that the toner is not new, and the toner supply motor is driven according to the output voltage of the toner sensor.

As described above, the developing tank cartridge is provided with the fuse for initial detection and the terminal for the toner sensor in addition to the terminal for applying the bias voltage at the time of development. In addition, in order to prevent malfunction or malfunction of the main body side due to static electricity charged on the human body or developing tank cartridge at the time of replacement, a ground plate (also called a lightning arrester Are provided to prevent static electricity from escaping.

[0008]

However, since the conventional developing tank cartridge is provided with the positioning pin 15 on the outer side of the terminal portion as shown in FIG. 4, for example, the developing tank cartridge and the image forming apparatus main body. There is a problem in that the size of the connecting portion with is large. Further, the terminals of the conventional developing tank cartridge have a structure in which a coil spring made of a conductive elastic body is provided outside the boss made of resin as a center, as shown in FIG. For this reason, in order to prevent a short circuit between the terminal and the ground plate, the terminal insertion hole of the ground plate is enlarged to provide a large clearance, so that the space in the height direction of the ground plate also becomes large. It was

In view of the above problems, the main problem of the present invention is that the terminal portion of the developing tank cartridge also serves as positioning when the developing tank cartridge is attached, so that a positioning space is provided on both the developing tank cartridge and the main body side. It is to be able to reduce the size by deleting. Another object of the present invention is to simplify the process of attaching the initial detection substrate to which the ground plate is attached to the image forming apparatus main body.

[0010]

According to the present invention, in a developing device of an image forming apparatus for developing an electrostatic latent image with toner and transferring it to a printing sheet, ribs made of an insulating material are provided around terminals of a developing tank cartridge. And a hole for receiving the rib is provided in the ground plate of the initial detection board of the image forming apparatus, the developing tank cartridge can be positioned by the rib, and the rib connects the terminal of the developing tank cartridge and the ground plate. The problem is solved by preventing a short circuit. Further, in the developing device, the holes of the ground plate may be arranged in one row, the hole at one end thereof may be a round hole, and the hole at the other end may be a long hole elongated in the arrangement direction. In the developing device, the material of the ground plate may be a leaf spring material, the ground plate may be provided with a cut and raised shape, and the ground plate may be attached to the image forming apparatus by a hooking method using spring elasticity.

[0011]

In the present invention, by providing the rib made of an insulating material around the terminals of the developing tank cartridge,
It is possible to prevent a short circuit between the terminal and the main body side ground plate. Further, a hole for receiving the rib is provided at a position of the ground plate corresponding to the rib, and the rib can be used as a positioning pin when the developing tank cartridge is mounted on the main body. This eliminates the need to provide a positioning pin separately from the terminal portion of the developing tank cartridge.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will now be described with reference to the drawings. FIG. 6 is a sectional view of a laser printer to which the present invention is applied. In the figure, the outline of the operation of the printing mechanism is as follows.

First, the photoconductor drum 27 rotatable in the direction of the arrow is uniformly charged by the charger 25. Next, while the polygon mirror 30 scans the laser beam 39 modulated according to the density of the image, the photosensitive drum 27
To form an electrostatic latent image. In synchronization with this, the printing paper is taken out from the paper feeding cassettes 21 to 22,
It is carried to the position just before the transfer roller 26. Next, the electrostatic latent image on the photosensitive drum 27 is developed with toner by the developing tank cartridge 1 and transferred onto the printing paper by the transfer roller 26. Next, the printing paper on which the toner image has been transferred is heated and fixed by the fixing device 29, and is discharged to the outside of the machine.

FIG. 5 is a perspective view of the developing tank cartridge 1 and the toner cartridge 23 that supplies toner to the developing tank cartridge 1.

FIG. 1 is a perspective view showing the periphery of the terminal portion of the developing tank cartridge 1 and the ground plate 5 on the initial detection board 4 on the main body side. In the figure, at the bottom of the developing tank cartridge 1, cylindrical ribs 2 formed integrally with the cartridge body with synthetic resin are arranged in one row. At the center of each rib 2, there is a hole through which the coil spring passes. Further, the tips of the ribs are chamfered in consideration of insertability. The winding spring whose tip is formed in a U shape is passed through the hole of the rib 2 and then the U shape portion is screwed to form the terminal 3. The fuse 7 for initial detection is connected to the terminals at both ends.

On the other hand, on the main body side where the developing tank cartridge 1 is set, an initial detection board 4 for relaying a signal of a toner sensor and a signal for checking the state of a fuse,
There is a ground plate 5 mounted on it. The earth plate 5 is provided to release static electricity charged on the human body to the ground when the developing tank cartridge is replaced,
It is connected to the frame ground (FG) of the image forming apparatus main body.

Further, the earth plate 5 is provided with holes 6 corresponding to the respective ribs 3 of the developing tank cartridge 1. In the initial detection board at the bottom of the hole 6,
At a position facing the terminals of the developing tank cartridge, there is a conducting surface made of nickel-plated copper foil. This conducting surface is
It serves as a terminal on the side of the initial detection board and comes into contact with the terminal of the developing tank cartridge.

Further, the shape of the hole of the earth plate 5 is
In order to align the developing tank cartridge 1, the hole at one end is a round hole 6a having a fitting shape with the developing tank cartridge rib shape, and the hole at the other end is an elongated hole 6b. The holes 6a and 6b may be formed in the shape of squeezed holes instead of being merely punched holes in order to prevent the ribs from being scraped when the developing tank cartridge is inserted or removed.

For the purpose of positioning the developing tank cartridge, the holes 6a and 6b are more advantageous as the distance between them is longer. Therefore, the terminals for the toner concentration sensor, the terminals for the developing bias voltage, etc. are arranged between them. The holes of the ground plate corresponding to the terminals provided between them are larger than the outer diameter of the terminal ribs and have a clearance. FIG. 3 is a cross-sectional view showing a state of fitting of the terminal portion.
Shown in.

FIG. 2 is an assembly diagram showing the assembly of the initial detection board 4 and the ground plate 5 and the attachment of the initial detection board 4 to the main body 20 of the image forming apparatus. In FIG. 4A, the ground plate 5 in which the outer shape, the hole 6, and the cut-and-raised shape 8 are simultaneously formed by the punching process is a long rectangular hole in the initial detection substrate 4 after being bent into a box shape. Then, it is bent and stopped through the bent portion 9.

The initial detection board 4 thus integrated with the earth plate 5 has the other end having the cut-and-raised shape 8 of the earth plate by hooking the board end portion to the main body frame rib 11 as shown in FIG. Press in the ends. When the substrate is in the correct position, the spring of the cut-and-raised shape 8 returns to fix the substrate, so screwing is not necessary.

[0022]

As described above, in the present invention, the ribs provided around the terminals of the developing tank cartridge are
By using it for positioning when replacing the cartridge,
The positioning pin, which has been separately provided conventionally, is not required, and there is an effect that the developing tank cartridge structure can be simplified and the initial detection substrate can be miniaturized. Further, the rib of the insulating material around the terminals of the developing tank cartridge can prevent a short circuit between the ground plate and the terminal, so that the height of the ground plate from the initial detection board can be lowered and the inside of the image forming apparatus can be reduced. This has the effect of saving space. In addition, the cut and raised shape of the earth plate,
Since the hooking method using the spring characteristic does not require screwing, there is an effect that workability of assembly is improved.

[Brief description of drawings]

FIG. 1 is a perspective view of a developing tank cartridge terminal portion and an initial detection substrate of the present invention.

FIG. 2 is an assembly diagram of a ground plate and an initial detection board.

FIG. 3 is a cross-sectional view showing how a developing tank cartridge terminal rib and an initial detection board are inserted and fitted.

FIG. 4 is a cross-sectional view showing how a conventional developing tank cartridge terminal portion and an initial detection board are inserted and fitted.

FIG. 5 is a perspective view showing a toner cartridge and a developing tank cartridge.

FIG. 6 is a sectional view of an image forming apparatus to which the present invention is applied.

[Explanation of symbols]

 1 Development Tank Cartridge 2 Rib 3 Terminal 4 Initial Detection Board 5 Ground Plate 6a Hole (Round Hole) 6b Hole (Elongated Hole) 7 Fuse 8 Cut and Raised Shape 9 Bending Stopper 11 Body Frame Rib 20 Image Forming Device 23 Toner Cartridge 27 Photosensitive Body drum 39 laser beam

Claims (3)

[Claims] 1. In a developing device of an image forming apparatus for developing an electrostatic latent image with toner and transferring it to a print sheet, ribs made of an insulating material are provided around terminals of a developing tank cartridge to detect an initial of the image forming apparatus. The ground plate of the substrate is provided with a hole for receiving the rib, the rib can position the developer tank cartridge, and the rib prevents a short circuit between the terminal of the developer tank cartridge and the ground plate. Development device. 2. The developing device according to claim 1, wherein the holes of the ground plate are arranged in one row, the hole at one end thereof is a round hole, and the hole at the other end is a long hole elongated in the arrangement direction. . 3. The spring according to claim 1 or 2, wherein the material of the earth plate is a leaf spring material, the earth plate is provided with a cut-and-raised shape, and the earth plate is attached to the image forming apparatus by spring elasticity. A developing device characterized by a hooking method.