JPH0623902B2 - Transfer device such as electronic copying machine - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transfer device used in an electronic copying machine, a laser beam printer or the like (hereinafter referred to as a copying machine).

2. Description of the Related Art Conventionally, a transfer device as shown in FIG. 6 is used in an electronic copying machine or the like. In the transfer device, a shield case b having an opening on the side of the photoconductor a is provided in the vicinity of the photoconductor a, and a corotron wire d to which a DC power source c is applied is stretched in the shield case b. The peeling corotron e is juxtaposed adjacent to this.

In the transfer device as described above, the paper f to be transferred is guided by the chute g, enters the electric field formed between the corotron wire d and the photoconductor a, and is transferred onto the surface of the photoconductor a.
Are electrostatically adsorbed, and the toner image formed on the surface of the photoconductor a is transferred to the paper f.

The chute g for guiding the paper f has a high resistance, for example, 10
It is grounded via a resistance h of 0 MΩ, and this high resistance h
Thus, when a highly water-containing paper or the like is carried in, a self-bias voltage is generated by the current flowing through the paper f to the chute g so that good transfer can be obtained even with the highly water-containing paper.

Problems to be Solved by the Invention However, when the paper f is a high water content paper, in addition to flowing through the paper f to the chute g, it also flows through the paper f to the peeling corotron e side installed adjacent to the transfer device. Therefore, even if only the chute g side is grounded via the high resistance h, in the case of a high water content paper, a transfer defect such as a decrease in copy density as shown by a broken line in FIG. 4 occurs as the water content increases. There was a problem.

The present invention has been made for the purpose of improving the above problems.

Means and Actions for Solving Problems In order to achieve the above object, the present invention transfers a toner image formed on the surface of a photoconductor to a sheet by a transfer device main body, and at the same time, transfers the completed sheet to the above-mentioned transfer. In an electronic copying machine or the like that peels from the surface of the photoconductor by a peeling corotron installed in the rear of the apparatus main body, a constant current supply means and a constant voltage element are connected in parallel to a conductive chute that guides the paper to the transfer area of the transfer main body. Since the bias current and bias voltage are applied from the circuit, the electric field necessary for the transfer can be secured in the transfer area even when transferring to the high water content paper.

Embodiment An embodiment of the present invention will be described in detail with reference to the drawings. In the drawing, 1 is a photoconductor provided in an electronic copying machine or the like, and 2 is a transfer device provided at a transfer position of the photoconductor 1. The main body includes a shield case 3 having an opening on the side of the photoreceptor 1, and a corotron wire 5 stretched in the shield case 3 and to which a DC power source 4 is applied.

Further, in front of the main body 2, there is provided a chute 7 for guiding the paper 6 to be transferred into a transfer area formed between the photoconductor 1 and the main body 2, and the chute 7 is a constant current supply means. 8 and constant voltage element 9 such as Zener varistor
Is grounded through a parallel circuit. The constant current supply means 8 comprises a high voltage generator 8a and a high resistance 8b used for supplying a DC high voltage to a corotron wire of a charger or a transfer device (not shown), and a resistance 8b higher than that of the high voltage generator 8a.
A predetermined current is supplied to the chute 7 as a bias current via the.

In the embodiment, the zener voltage V _z 950 of the constant voltage element 9 is
V, output of high voltage generator 8a 5.4KV, resistance value 77MΩ of high resistance 8b is used, 70μA at the time of short circuit of chute 7
The short-circuit current of was made to flow.

As the constant current supply means 8, a constant current power source 8c may be used as shown in FIG.

On the other hand, behind the transfer device main body 2, a peeling corotron 10 for peeling the paper 6 after the transfer from the photoconductor 1 is provided adjacent to the main body 2. The peeling corotron 10
Is constructed by stretching a corotron wire 10b to which an AC power source 11 is applied in a shield case 10a having an opening on the side of the photoreceptor 1.

Next, the operation will be described. The transfer image quality of the high water content paper is improved as the bias voltage is increased as shown in FIG. 2, and is stabilized when the voltage exceeds a certain threshold voltage A.
When this threshold voltage A is applied to the chute 7 as a bias voltage, the current B (see FIG. 3) flowing from the constant current supply means 8 into the paper 6 through the chute 7 obtains a good transferred image on the high water content paper. The bias current A and the bias current B are required to supply to the chute 7 by the parallel circuit of the constant voltage supply means 8 and the constant voltage element 9 so that a good transferred image can be obtained even with high water content paper. Will be available.

As described in detail above, according to the present invention, the conductive chute 7 for guiding the sheet 6 to the transfer area of the transfer device main body 2 is provided with the bias current and the voltage by the parallel circuit of the constant current supply means 8 and the constant voltage element 9. As a result, the high water content paper is carried in as the transfer paper 6, the conductive part is short-circuited by the paper 6, and the charge in the transfer area escapes to the peeling corotron 10 side via the paper 6. However, since an electric field that allows good transfer due to the bias current is always present in the transfer area, it is possible to obtain a stable copy image with a copy density as shown by the solid line in FIG. 4 even with high water content paper. Become. Further, since the bias is applied to the existing conductive chute 7, the structure is simpler and the cost can be provided at a lower cost than that in which a conductive brush member or the like is separately provided.

[Brief description of drawings]

The drawings show an embodiment of the present invention, FIG. 1 is a schematic configuration diagram, FIGS. 2 to 4 are explanatory views of operation, FIG. 5 is an explanatory view showing another embodiment, and FIG. FIG. 1 is a photoconductor, 2 is a transfer device main body, 6 is paper, 8 is a constant current supply means, 9 is a constant voltage element, and 10 is a peeling corotron.

Claims (1)

[Claims] 1. A toner image formed on the surface of a photoconductor 1 is transferred onto a sheet 6 by a transfer device main body 2 and the transfer completed sheet 6 is transferred by a peeling corotron 10 installed behind the transfer device main body 2. In an electronic copying machine or the like that separates from the surface of the photoreceptor 1, a conductive chute 7 that guides the paper 6 to the transfer area of the transfer device body 2 is biased by a parallel circuit of a constant current supply means 8 and a constant voltage element 9. And a transfer device such as an electronic copying machine to which a bias voltage is applied.