JPS5912458A - Form guiding device of electronic copying machine - Google Patents

Abstract

PURPOSE:To carry out excellent transfer regardless of humidity, by grounding a metallic form guide which guides and superposes a conveyed copying form upon the surface of a photosensitive drum through a switch. CONSTITUTION:An electronic copying machine is equipped with the metallic form guide 7 which guides the conveyed transfer form 4 and superposes it upon the surface of the photosensitive drum 1. This form guide 7 is grounded through the switch 11. The switch 11 is opened at high humidity to insulate the form guide. Then, even if the transfer form 4 contains much water, no charge from a transfer electrifier 5 flows to the form guide 7 and a transfer defect resulting from that is eliminated.

Description

[Detailed description of the invention] The present invention relates to a paper guide device for an electronic copying machine.

FIG. 1 shows a schematic diagram of a conventional electronic copying machine. In this electronic copying machine, the surface of the photoreceptor drum 1 rotating in the direction of the arrow is charged to Φ with a charger (charging=1 [11 to [Jn]2), and a light image is exposed to form an electrostatic latent image. The electrostatic latent image is developed with toner particles 3 carrying an e-charge.

The toner image thus obtained is transferred at a predetermined timing onto copy paper 4, which is transported in the direction of the arrow by a transport device (not shown). This transfer is performed by charging the copy paper 4, which is aligned with the toner image on the photoreceptor drum 1, to Φ using a transfer charger (transfer corotron) 5, and toner particles 3 are attracted to this by electric attraction force. J, will be held. After the transfer, the copy paper 4 is peeled off from the surface of the photosensitive drum 1 and sent to the fixing device 6, where it is fixed and a copied image is obtained.

Incidentally, in such an electronic copying machine, a paper blade 7 is provided in front of the copy paper 4 in order to guide the copy paper 4 being conveyed and superimpose it on the surface of the photosensitive drum 1.

The paper guide 7 is generally U-shaped as shown in FIG. 1 in large-sized copying machines, and in small-sized copying machines, a chute-shaped paper guide 7 is used. However, since the paper guide 7 is usually made of metal kT, if it is grounded and the copy paper 4 contains moisture due to high humidity, the charge given by the transfer charger 5 will be transferred to the paper guide 7. This can cause transfer defects.

Therefore, in such conventional electronic copying machines, a method is adopted in which the paper guide 7 is insulated. However, in this method, the following drawbacks occur when the moisture content of the copy paper 4 decreases at low humidity and its surface electrical resistance increases. The electrical attractive force between the copy paper 4 and the surface of the photoreceptor shim 1 increases, resulting in a large difference in the attractive force between the area where there is a toner image and the area where there is no toner image. As a result, as shown in FIG. 2, the copy paper 4 is rapidly attracted to a portion of the surface of the photosensitive drum 1 where there is no tonneau image 8, and then to a portion where the toner images 1 to 8 are present. For this reason, air pockets are formed in the latter portion, which has the disadvantage that transfer defects are likely to occur locally.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a paper guide device for an electronic copying machine that can perform good transfer in both high humidity and low humidity conditions.

In the present invention, a metal paper guide is grounded through a switch, and when the humidity is high, the switch is opened to put the paper guide in an insulating state, and when the humidity is low, the switch is opened and the paper guide is in a grounded state, thereby achieving the above-mentioned object.

The present invention will be described in detail below with reference to Examples.

FIG. 3, in which parts of FIG. 1 and 41 are denoted by the same reference numerals, is a schematic diagram of a paper guide device of an electronic copying machine. In this device, the paper guide 7 made of sheet metal is connected to the switch 11.
is grounded through.

The switch 11 is provided at a location that is normally closed off by the operation panel or cover of the electronic copying machine.

For example, when the humidity is high, such as during the rainy season, the switch 11 is opened and the paper guide 7 is insulated. Then, even if the copy paper 4 contains a lot of moisture, the charge applied by the transfer charger 5 will not flow to the paper guide 7, and transfer defects caused by this will be eliminated.

On the other hand, when the humidity is low, such as in winter, the switch 11 is closed and the paper guide 7 is grounded. In this case, even if the surface electrical resistance of the copy paper 4 is high, the electrical attractive force between the copy paper 4 and the surface of the photoreceptor drum 1 will not increase. Therefore, the copy paper 4 is uniformly attracted to the surface of the photoreceptor drum 1 without forming any air pockets, thereby eliminating transfer defects caused by this.

In the above embodiment, the switch 11 is provided on the operation panel or the like, and the operator makes the switch, but the invention is not limited to this. For example, as shown by the dashed line in FIG. 2, the switch 11 may be electrically switched by the humidity sensor 12. In this case, the switch 11 is one that is switched by an electric signal.

According to the present invention as described above, good transfer can be performed even in high humidity or low humidity by switching the switch, so when copy paper that easily absorbs moisture and copy paper that does not easily absorb moisture are used at the same time. However, it is possible to easily adjust the copying conditions to suit each paper.

Therefore, there are restrictions on the type of copy paper.
Y-type transfer can be performed. Also, if the electronic copying machine is installed in a place that is prone to high or low humidity,
It can be supported by different models. Also set a switch ()
The configuration is simple and can be made with low JST.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing an example of a paper guide device of a conventional electronic copying machine, and FIG. 2 is a diagram for explaining its drawbacks.
FIG. 3 is a schematic diagram showing a paper guide device of an electronic copying machine according to an embodiment of the present invention. 1... Photosensitive drum 4... Copy paper 5... Transfer charger 7... Paper guide 11... Switch application Hitofuji U Rocks Co., Ltd. Ne1 Representative Patent Attorney Yamauchi IIkJkJi

Claims (1)

[Claims] A paper guide device for an electronic copying machine, comprising a metal paper guide for guiding the transported copy paper and overlapping it on the surface of a photoreceptor drum, and the paper guide is grounded via a switch.