JPS63138376A - Image forming device - Google Patents

Abstract

PURPOSE:To obtain electric safety by providing a switching means which places the part of a fixing device in a floating state in the earth or connects it to the earth through a high resistance when an opening/closure part is closed and connects the part of the fixing device to the earth when the opening/closure part is open. CONSTITUTION:When a paper discharging part 18 is closed, an electrode 26 and an electrode leaf spring 27 do not contact each other and the fixing device 6 is grounded through a varistor 28 with high resistance, so transfer is performed normally. If paper jams or if the paper discharging part 18 is opened by mistake, on the other hand, the electrode leaf spring 27 contacts the electrode 26 by its own spring force in the absence of an arm 25, so the arm 25 leaves the spring 27 when the paper discharging part 18 is opened and the fixing device 6 is conducted to the earth. The fixing device 6 is therefore grounded and its potential is zero while the paper discharging part (paper discharging unit) 18 is open, so it is safe even when said device is touched.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an image forming apparatus, particularly an image forming apparatus of a type that can be opened for jam removal in an in-machine fixing device and its vicinity. Specifically, it concerns the grounding of the fuser.

(Prior Art) Each image forming device has high-voltage parts that are dangerous to touch.

Taking an electrophotographic copying machine as an example, normally, in an electrostatic copying machine, a toner image on an image carrier is transferred onto a transfer paper by, for example, corona discharge of a transfer charger, and the transferred image is This method uses a fixing device to fix the image onto the transfer paper.

Therefore, if the resistance of the part that comes into contact with the transfer paper during transfer to the ground is low, the corona discharge current will pass through the transfer paper and escape from the contact part to the ground, especially in high temperature and high humidity environments. There is a possibility that normal transcription may not occur.

As a countermeasure for this, guides that come into contact with the transfer paper should be floated, or if the unfixed image is disturbed due to charge build-up due to the float, it should be grounded via a varistor with a resistance of several hundred MΩ (usually more than 100 MΩ). As a result, it may have a positive voltage of several hundred volts or more.

(Problems to be solved) In this way, parts that are grounded via a float or varistor may have a potential of several hundred volts or more due to charge-up, and therefore it is dangerous for the user to touch them directly with their fingers. I need to cover it so my fingers don't touch it. However, it is necessary to open the transfer paper ejection port of an image forming device in order to clear paper jams between the paper ejection port and the fixing device, and the paper is usually opened wide by operating a knob or the like. Although it is possible to put one's hand inside the machine, there is a problem in that one's fingers touch the fixing roller and the metal part that is electrically connected to the roller.

(Means for Solving the Problems) The present invention aims to solve the above-mentioned problems and eliminate the drawback of fingers touching metals with electric potential. An opening/closing part provided so as to be openable/closable so as to open the vicinity thereof, and a means for switching the opening/closing part of the opening/closing part in conjunction with each other, and when the opening/closing part is closed, the fuser part is floated with respect to ground. The apparatus is characterized in that it is provided with a switching means that connects the fixing unit to ground through a high resistance and connects the fuser part to ground when the opening/closing part is opened.

(Example) Hereinafter, one example of the present invention will be described based on the accompanying drawings.

FIG. 1 and FIG. 2 are main part configuration diagrams of an embodiment of the present invention,
Each shows the state when the opening/closing part is opened and when it is opened.
Furthermore, FIG. 3 shows the overall configuration of a copying machine to which the present invention can be applied.

This copying machine has a cover over the paper output slot, and when the cover is closed, you cannot touch the interior of the machine with your fingers, and when the cover is open, there is electrical conduction with the fuser roller and/or fuser roller inside the machine. The structure is such that you can touch the metal parts with your fingers.

First, as shown in FIG. 3, the copying machine has a paper feed roller l, and the transfer paper P sent out from the cassette 2 by the drive of the paper feed roller l is sent out after adjusting the sending timing by the registration roller 3. Then, it is sent to the photosensitive drum 9 via a conveyance drive roller 4.

Around the photoreceptor 9, there are a charger 13, a SELFOC lens array 17, a developing device 10. A transfer charger 14°, a separation claw 15, a cleaning device 11, etc. are provided, and the transfer paper P that is in contact with the photosensitive drum 9 is transferred through a well-known electrophotographic process and then exposed to light by the separation claw 15. The separated transfer paper P is separated from the body drum 9 and is transported to a fixing device 6 by a conveyor belt 5 between a transmission driven roller 7 and a transmission drive roller 8. Facing the fixing unit 6, there is an openable/closable part that can be opened at the position indicated by the two-dot chain line when clearing paper jams, etc., i.e., in the case shown in the figure, a paper ejection part (paper ejection unit) as a paper ejection port cover.
18, and the transfer paper P is discharged outside the machine through the paper discharge section 18 after being fixed.

Note that 12 is a light source, and 16 is a document placement glass. In this embodiment, in the sheet discharge section 18 and the fixing device 6 as described above, when the sheet discharge section 18 is closed, the fixing roller and the metal part that is electrically connected to the fixing roller are grounded via a varistor. When the paper discharging section 18 is open, the fixing roller and the metal part are grounded in conjunction with the opening and closing of the paper discharging section 18, and FIG. 1 shows the fixing device 6 having such a structure.
FIG.

The fixing device 6 has an upper fixing roller 20 and a lower fixing roller 21. Both the rollers 20 and 21 are not shown in the figure or are electrically connected to a frame that holds the rollers. The rollers are conducting.

This fuser 6 is floating from the ground and fixed to the main body of the copying machine, and a varistor 2 as a high resistance is connected to a part of the fuser 6.
It is grounded through 8.

Further, the fixing device 6 is electrically connected to the electrode 26. The paper ejection section 18 is made of insulating plastic, has an upper paper ejection roller 22 and a paper ejection roller 23, and is configured to eject the transfer paper that has passed through the fixing device 6 by a driving force (not shown). When dealing with a paper jam or the like, the paper discharge section 18 can be opened in the direction of arrow A around the shaft 24 by removing a latch (not shown) (see FIG. 2) to expose the fixing device 6. As shown in Figure 1, in the normal closed state, the paper ejection section 1
The fixing device 6 cannot be touched with fingers from outside of the fixing device 8 .

The paper discharge section 18 has an arm 25 near the shaft 24 at a location where it does not come into contact with the fixing device 6 even when rotated.
- An electrode plate spring 27 as a switching means that is pressed down by the arm 25 is arranged at a position facing the electrode 26, and the electrode plate spring Z7 is connected to the ground. In the state shown in Fig. 1 when 8 is closed, the electrode 26 and the electrode plate spring are not in contact with each other because the arm 25 is pushing down the electrode spring 27 which is electrically connected to the ground. .

Next, the operation of the above-described configuration will be explained. In the state shown in FIG. 2, the electrode 26 and the electrode plate spring 27 are not in contact with each other as described above, and the fixing device 6 is grounded via the high-resistance varistor 28, so that the transfer is performed normally.

However, as shown in FIG.
If 5 or no, the electrode plate spring 27 will push the electrode 26 with its own spring force.
Since the structure makes contact with the arm 25, when the paper ejection section 18 is opened, the arm 25
The fixing device 6 is connected to the ground from the spring 27. Therefore, when the paper ejection section (paper ejection unit) 18 is open, the fixing unit 6 is grounded and the potential is O.
Therefore, it is electrically safe even if touched.

In this embodiment, when in the closed state shown in FIG. 1, it is grounded via the varistor 28, or it may be configured to float with respect to the ground.

In addition, although the electrode plate spring 27 is used, the electrode plate spring 27
You can also use a micro switch instead. The key is to connect the opening and closing of the opening/closing section with grounding.

Switching between high resistance and float is a feature of the present invention.

(Effects of the Invention) As described above, according to the present invention, the fuser part is grounded when it can be touched with a finger because it switches between ground, high resistance, and float by opening and closing the opening/closing part. It is electrically safe and can prevent accidents.
This effect can be obtained.

[Brief explanation of the drawing]

FIG. 1 shows the main part configuration I of a copying machine according to an embodiment of the present invention, including the contact relationship when the paper ejection section is closed near the paper ejection port.
A. FIG. 2 is a configuration diagram of the main parts including contact relationships when the paper discharge section is open, and FIG. 3 is a diagram showing the overall structure of the copying machine. 6...Fuser 18...Opening/closing section (paper ejection section) 27...
...Switching means (electrode plate spring) 28...
...High resistance (varistor) patent applicant Canon Co., Ltd. agent Patent attorney Fujioka
Toru Figure 1

Claims (1)

[Scope of Claims] An opening/closing part provided to be openable and closable so as to open a fuser in the machine and its vicinity, and means for switching in conjunction with opening/closing of the opening/closing part, when the opening/closing part is closed. The fixing device is characterized by having a switching means that either floats the fuser portion with respect to the ground or connects it to the earth via a high resistance, and lowers the fuser portion to the ground when the opening/closing portion is opened. Image forming equipment.