JPS6232480A - Transfer and separation device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] (11.Object of the invention (industrial application field)) This invention relates to an image forming apparatus that uses an electrostatic transfer process, such as an electrophotographic copying machine or a printer, and particularly to a transfer separation device thereof. .

(Prior Art and Issues to be Solved) In well-known image forming apparatuses such as Nanitsu, as is well known, toner images electrostatically adhered to the surface of an image carrier are mainly formed on paper. A sheet-like transfer material is brought into contact with or in close proximity, and a transfer charger applies an electric charge of opposite polarity to the normal toner to the transfer material in this area, transferring the toner to the transfer material. There are a wide variety of devices in practical use that are configured to eliminate the tendency of the transfer material to stick to the image carrier by applying a charge of opposite polarity to the image carrier to remove the charge during transfer.

In this type of image forming apparatus, fine and light toner on the order of microns is supplied from a developing device to an image bearing member, transferred from the image bearing member to a transfer material, and residual toner that was not transferred to the image bearing member during transfer is removed. Forcibly remove it using a cleaner,
Furthermore, all operations such as conveying the transfer material to the fixing site after transfer are performed using relatively weak and unstable forces such as the electrostatic attraction of the toner to other objects, so toner cannot be completely controlled. It is virtually impossible to prevent its scattering.

In addition, various foreign substances such as fine paper dust, fine precipitates such as rosin, talc, and kaolin, and corona products inevitably generated from the presence of each charger are present in the paper-based transfer material used in the device. We cannot help but become prone to a state of floating within ourselves.

Furthermore, since ozone is generated due to corona discharge from each charger, this causes image blurring, so a method has already been proposed that actively eliminates ozone near the transfer charger. This type of device is normally configured to have an opening at the bottom of the shield case of the charger to suck in the surrounding air, but when configured in this way, various types of This is undesirable because the foreign matter will be attracted to the charger, and the floating foreign matter will adhere to the discharge wire and contaminate it, resulting in image deterioration and unstable separation.

The present invention has been made in order to cope with such a situation, and in the image forming apparatus as described above, air is sucked through an opening formed on the back side of the transfer separation charger, and the temperature and humidity of the environment are detected. However, it is an object of the present invention to provide a transfer separation device that can suck air only when it is highly necessary, thereby minimizing contamination of the charger.

(2) Structure of the invention (technical means for solving the problem and its operation) In order to achieve the above object, the present invention provides a shield case rear surface of at least one of the transfer and separation chargers in the image forming apparatus as described above. At the same time, a suction duct is formed to eliminate the generated ozone, and the fan that generates the air flow in the suction duct is detected by a temperature and humidity sensor or a temperature sensor, and the environmental condition is within a predetermined range. The fan is configured to operate only at certain times.

With this configuration, the generation of airflow for removing ozone can be minimized, thereby reducing contamination of the discharge wire, and providing a stable transfer/separation effect over a long period of time.

(Description of Embodiments) FIG. 1 is a schematic side view of the main parts showing an embodiment in which the present invention is applied to a copying machine equipped with a rotating cylindrical image carrier (photoreceptor).

The photoreceptor 1 rotates in the direction of arrow A, and the toner image formed on its surface photosensitive layer reaches a transfer site where a transfer charger 3 is arranged as the photoreceptor rotates. At this time, the transfer material (not shown) conveyed from the direction of the transfer material path 2
The toner image contacts or approaches the toner image at the transfer site, and at this time, the transfer charger applies a charge of opposite polarity to the toner to the transfer material, thereby transferring the toner image to the transfer material.

Next, the transfer material is charged with a charge having a polarity opposite to that of the transfer charger by a separation charger 4, and the transfer material is neutralized and separated from the photoreceptor, and passes through a conveyance path 9 to a fixing site (not shown). shall be taken as a thing.

As is well known, around the photoreceptor 1,
A primary charger that uniformly charges the photosensitive layer, a portion that projects a light image onto this to form an electrostatic latent image, a developer that supplies toner to the latent image to form a toner image; A cleaner that removes residual toner that does not transfer to the transfer material and remains on the photoreceptor at the transfer site, residual charge? It goes without saying that static eliminating means and the like are provided, but since these are not directly related to the present invention, a description thereof will be omitted.

Returning to FIG. 1, it is assumed that openings 3a and 4a are formed in the back surface of the shield case of the transfer 1-separation charger, respectively, and these openings reach appropriate locations outside the apparatus through the entire duct 5.

A fan 6 is disposed within the duct 5 and is operated by a drive source 6a such as a motor that is controlled on and off by a control unit 7. Further, the control section 7 operates to turn on and off the fan 6 by comparing the temperature and humidity sensors with predetermined reference values.

Figure 2 shows the temperature range that determines whether the fan is turned on or off.
It is a graph of humidity, and it is activated or deactivated when there is temperature and humidity in each on/off region.

FIG. 3 is a humidity graph showing a region where fan on/off is limited when only a humidity sensor is used.

Note that, for example, a thermistor can be used as the temperature sensor, and a ceramic sensor can be used as the humidity sensor.

(3) Effects of the Invention Since the present invention has the above-described configuration, the fan can be turned on in high humidity conditions where image deletion is likely to occur, and the fan can be inactivated as much as possible in low humidity conditions, thereby reducing the charge per transfer charge. This has the effect of minimizing contamination of the device's discharge wire and providing stable images over a long period of time.

[Brief explanation of the drawing]

Fig. 1 is a schematic side view of the main parts showing an embodiment in which the present invention is applied to a copying machine, Fig. 2 is a graph defining the operating and non-operating areas of the fan, and Fig. 3 is when only the humidity sensor is used. This is a graph showing an area where fan on/off is limited.

Claims (1)

[Claims] An opening made in the back side of the case of at least one of the transfer charger and the separation charger, which is surrounded by a shield case on the side other than the side facing the image carrier, is communicated with a duct equipped with a suction fan, and the suction fan is connected to the environment. A transfer separation device of an image forming apparatus that turns on and off depending on temperature and humidity.