JPS6015667A - Image forming device - Google Patents

Abstract

PURPOSE:To reduce effectively the dirt of a transfer sheet due to a toner by connecting a high frequency oscillating means to at least one of various members, which are brought into contact with the carried transfer sheet, or devices incorporated therein. CONSTITUTION:Paper carrying guides 22 and 22' are grounded through a resistance 26 for the purpose of preventing the omission of transfer at a high temperature and may be held in a potential of about several hundreds V because of paper friction or the like and attract the toner on a photosensitive drum 20 and the scattered toner. An ultrasonic oscillator 27 is brought into contact with the tip of the guide 22 to oscillate it as shown by a dotted line, and the stuck toner is removed downward physically to keep this part clean. The ultrasonic oscillator is connected to an oscillating circuit 28, and the circuit 28 is connected to a timing setting circuit 29, and timing of this oscillation is matched properly to the operation of a copying machine.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an image forming apparatus that uses toner to develop a latent image on an image carrier formed by electrophotography or a laser beam. This invention relates to preventing staining of a transfer sheet conveyed within an image forming apparatus.

A conventional general electrophotographic copying machine is shown in FIG. 1. A photosensitive drum 1 rotating in the direction of the arrow is uniformly charged by a charger 2, and then a document 3 is illuminated with a lamp 4. A latent image is formed by forming an image on the photoreceptor through the short focal length lens array 5, and the latent image is developed by the developing device 6 at the edge thereof. The transfer sheet 10 is conveyed through the guides 11 and 13 by the drive of the transfer sheet 12, and the toner image is transferred by the charger 7. After the transfer, the transfer sheet is separated from the photosensitive drum by a separation belt 14, passes through a conveyance belt 15, a fixing paper guide 17, and is fixed by a fixing device 16. Further, residual toner on the photoreceptor is removed by a cleaning blade 8. This is the general process.

Incidentally, inside the image forming apparatus as described above, it is inevitable that various contaminations occur due to toner, which is an image developing agent. For example, in the case of dry development in the developing unit 6, toner of about 10 microns always rotates on the developing roller, and although it is attracted to the developing roller side by magnetic force, the magnetic force is weak. Toner has weak adsorption power to the developing roller and scatters. Furthermore, even if the toner is attracted to the photosensitive drum by electrostatic force, the toner with a low electric charge has a weak adsorption force to the photosensitive drum and cannot be avoided from scattering. It is also difficult to completely collect the residual toner removed by the cleaning blade 8, and the toner falls and scatters through the magnetic collection roller 18, contaminating the conveyor belt 15, and furthermore, the separation belt 14 or If the sheet fluctuates when the transfer sheet F is caught in the fixing roller 16, the toner on the transfer sheet will scatter from the transfer sheet, contaminating the separation bell i or the fixing conveyance guide 17, as well as the developing device. 6. Scattered.

The fallen toner ends up contaminating the paper guide 13.

If the above-mentioned scattered or fallen toner adheres to the conveyance path of the transfer sheet, or to parts such as the conveyance guide that the transfer sheet comes into direct contact with, or to the device, the transfer sheet will be contaminated and toner will adhere to non-image areas. In addition, if toner remains attached to the fixing conveyance guide 17 for a long time, problems such as the toner becoming hard to form due to the heat of the fixing roller may occur, which may impair the conveyance of the transfer sheet. Ta.

The present invention has been made to solve the above-mentioned problems.The first problem is the problem of toner adhering to various parts of the device body, namely, the occurrence of stains on the transfer sheet. The purpose is to solve this problem easily, and secondly, this reduces the frequency of maintenance and inspection work, thereby extending the life of the device.

The gist of the present invention to achieve such an object is that in an apparatus fR that uses toner to form an image on a transfer sheet that is conveyed within an apparatus main body, the conveyed transfer sheet is The image forming apparatus is characterized in that a high frequency vibration means such as an ultrasonic vibrator is connected to at least one of various members that come into contact with each other or a built-in device.

The present invention is characterized by the fact that it is not limited to any type of device as long as it forms an image on a conveyed transfer sheet using toner; The invention can be applied not only to copying machines using electrophotography, but also to other devices.

The present invention will be described below based on embodiments shown in the drawings.

FIG. 2 shows how the present invention can be applied to a photosensitive drum of an electrophotographic copying machine.
This shows an example in which the guide is applied to a conveyance guide. In the figure, 20 is a photosensitive drum, 21a is
The developing roller 22, 22' is a pair of sheet conveyance guides that form a narrow path for sheet conveyance, 23 is a sheet separation bell), 24a is a transfer charger, and other structural parts of the copying machine are Since it is not directly related to the embodiment, illustration is omitted.

In the above configuration, the electrostatic latent image formed by exposing the original image to light is developed by the developing roller 21 using toner, and the photosensitive drum 21, which rotates in the direction of the arrow in the figure, is charged to ■. Toner having a charge of e is deposited on the latent image. And the transcription sheet shown by the dotted line) 2511
, upper and lower sheet conveyance guides 22 and 22'.

The sheet conveyance guide is often grounded via a resistor 26 to prevent transfer failure at high temperatures, and at this time, the paper guide is charged up due to friction with the transfer sheet, causing several hundred In some cases, a potential of about V is maintained.

Now, the sheet conveyance guide with such a configuration is such that the tip of the sheet conveyance guide on the lower side of the figure (section A in the figure) is always in contact with the transfer sheet, is closest to the surface of the photosensitive drum, and is Because it is generally located directly below the developing device, photosensitive drum, etc., it attracts toner with weak suction force on the photosensitive drum or scattered toner from the developing device, and is easily contaminated.

Therefore, in this example, this lower sheet conveyance guide 2
The ultrasonic vibrator 27 is brought into contact with the tip part of 2 (part A in the figure) and vibrated in the direction of the arrow to physically remove the adhering toner downward by the ultrasonic vibration, keeping part A clean at all times. I am able to maintain it.

Note that the ultrasonic transducer is connected to an oscillation circuit 28, and this oscillation circuit is connected to a timing setting circuit 29.
This oscillation can be performed appropriately by properly timing the operation of the copying machine.

Examples of the ultrasonic transducer 27 used in particular include barium titanate, zirconate titanate steel (PZT), and lead-raftane zircon-titanium oxide mixture (PLZ).
Materials exhibiting piezoelectric properties such as T) and organic materials can be used, and the vibrator may be a single plate, or it is also possible to use two or more laminated plates. The oscillation circuit 28 only needs to be able to apply an alternating electric field or an electric field equivalent thereto to the vibrator 27, and the direction of vibration may be in the direction of the arrow, but is not particularly limited as long as the vibration can be transmitted; Either diagonal direction is fine. As for the amplitude, it is effective to use a frequency of about several μm and a frequency of 10 kHz, but it is not limited to this, and it is several LcHz.
It can be used in the range from 1 to several MHz.

Note that it is desirable that the vibrator 27 be electrically insulated from the chest with which it is brought into contact.

Next, the relationship between the desirable timing of vibration application in this example will be described. The timing and duration of this vibration application are determined by the timing setting circuit 29, and it is generally recommended that the vibration be applied continuously while the device is in operation as long as it does not interfere with sheet conveyance. I can say it. Therefore, in this example, the vibrator is made to vibrate according to the relationship shown in the time chart of FIG. That is, when the user inputs a copy start signal, the photosensitive drum 20 starts rotating and enters a break-in rotation, which is usually referred to as pre-rotation. Output.

During this several seconds of operation, foreign matter such as toner that has adhered while the sheet is left unused is removed, leaving the sheet conveyance guide in a clean state.

Next, the actual copying operation begins, and the vibrator 27 is turned off in synchronization with the start of rotation of the o-ra (not shown) for driving the developing device and feeding the transfer sheet (time t! in FIG. 3). period). This is because if the vibrator 27 vibrates when the transfer sheet 25 is conveyed from the sheet conveyance guide to be brought into contact with oil on the photosensitive drum, the transfer sheet may flap.

When continuously copying a plurality of sheets, it is preferable to vibrate the vibrator between the copying of the first sheet and the copying of the second sheet (time tt-ts) since the flapping of the transfer sheet does not matter. After the last copy is completed, it is preferable to vibrate the vibrator for an appropriate time (time t4 to t5 in this example) to remove toner and the like.

In addition to the above-mentioned vibration timing of the vibrator, if the degree of vibration is such that the transfer sheet can be stably conveyed, it is possible to turn it on all the time while the drum is rotating, regardless of the timing signal.

Furthermore, the vibrator may be made to vibrate for a predetermined length of time when the cumulative time of the copying operation reaches a certain value. It may also be possible to drive it.

FIG. 4 shows an embodiment in which the present invention is applied to a sheet conveyance guide located upstream of the fixing device, and specifically, a sheet conveyance guide 31 located upstream of the fixing roller 30. At the same time, the ultrasonic transducer 32 is brought into contact with
The structure is such that the two are in contact with each other. Note that 35.36 indicates an oscillation circuit, 37.38 indicates a timing setting circuit, and 3.
Reference numeral 9 indicates a case of a toner receiver having a filter, and reference numeral 40 indicates a fan.

With this configuration, the ultrasonic vibrator 32 is vibrated in the direction of the arrow, and the toner scattered from the transfer sheet can be physically sieved downward and removed. The vibration direction is an example of a reed, and is not limited to the direction shown in the drawings, as in the previous example. In addition, the ultrasonic vibrator 34 in contact with the conveyor belt 33 vibrates the conveyor belt 33 contaminated with toner that has scattered and fallen from a part of the cleaner (not shown), thereby physically removing the toner. . In this example, the physically sieved toner is stored by suction in a case 39 and a case 40 having filters.

The application of the present invention is not limited to the above-mentioned embodiments, but may be applied to any or all of the members and devices that are built into the image forming apparatus and come into contact with the transferred transfer sheet. Examples of such objects include a transfer sheet supply device, a sheet guide, a charger such as a transfer charger, a sheet separation device from a photosensitive drum, a fixing device, etc. As already mentioned, the invention is not limited to photocopying machines.

Although it is possible to remove stains by bringing the vibrator into contact with a member or the like in the image forming apparatus main body that does not come into contact with the transfer sheet, this is not directly effective in preventing stains on the transfer sheet.

As described above, according to the present invention, it is possible to effectively alleviate problems such as staining of a transfer sheet caused by toner, which has occurred in conventional image forming apparatuses using toner, and its usefulness is great.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing an example of a conventional general electrophotographic copying machine, FIG. 2 is a schematic configuration diagram including a sheet conveyance guide section to which the present invention is applied, and FIG. 3 is the same as shown in FIG. 2. FIG. 4 is a timing chart diagram illustrating an example of the vibration timing of the ultrasonic transducer, and FIG. 4 is a schematic configuration diagram including a sheet conveyance guide section showing another embodiment of the present invention. 1.20: Photosensitive drum 2: Charger 3: Document 4: Illumination lamp 5: Lens array 6, 21: Developing roller 7.24: Transfer charger 8: Cleaning solade 9: Paper feed roller 10.25: Transfer sheet 11: Sheet conveyance gas rod 12 Ni registration rollers 13.22, 22': Sheet conveyance guide 14.23: Separation belt 15.33: Conveyance belt 16.30: Fixing roller 17.31: Sheet conveyance guide 26: Resistance 27.32 , 34: Vibrator 28. 35, 36: Oscillation circuit 29. 37, 38: Timing setting circuit 39: Toner receiver case 40: Fan.

Claims (1)

[Claims] In an apparatus that uses toner to form an image on a transfer sheet that is conveyed within the apparatus main body, a high-frequency vibration means is connected to at least one of various members that the conveyed transfer sheet comes into contact with or a built-in device. An image forming apparatus characterized by: