JPS6044662B2 - Charger for transfer/neutralization - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a charger for transferring and removing snow in an electronic copying machine.

In order to separate the transfer paper from the photoreceptor in an electronic copying machine, the transfer paper, which has been charged by the transfer charger during transfer, is charged with corona or alternating current, which is generated by a snow removal charger and has a polarity opposite to that of the transfer paper. Defrosting using corona was introduced in 1974.
This is well known from, for example, Japanese Patent No.-38731.

In AC corona, the voltage is symmetrical between positive and negative, as shown in Figure 1 a and b, but the negative component of the current is 3 times higher than the positive component.
Since it is 0 to 40% larger, it is not possible to completely defrost the transfer paper, and normally a DC bias is applied as shown in FIG. That is, a DC bias is applied by a DC power source D to the AC high voltage output of the transformer and applied to the electrode of the corona charger 1 to generate corona and defrost the transfer paper 4 on the photoreceptor 3. The value of this DC bias is set so that the corona current is approximately symmetrical in positive and negative directions, or under the conditions that the transfer paper is separated from the photoreceptor while not reducing the toner transfer efficiency. However, transfer paper is very sensitive to environmental conditions, especially humidity, and its volume resistivity decreases rapidly due to moisture absorption. For example, 10" at 65% of room temperature
The volume resistivity of ゜Ω-α becomes 10''゛Ω-a at 80%, and becomes less than 1010 Ω-a at 90%, and the charging potential also depends on humidity, as shown in Figure 3. For this reason, the above-mentioned snow removal charger has the disadvantage that it cannot effectively defrost the transfer paper when it is humid under the conditions set at room temperature.Also, the transfer paper is charged with the transfer charger and cannot be used to charge the photoreceptor. The same applies to the case where toner is transferred to transfer paper.The present invention eliminates the above-mentioned drawbacks,
To provide a charger for transfer and snow removal configured to be able to effectively perform transfer or defrost in any environment without reducing toner transfer efficiency by detecting humidity in the air and controlling corona current. With the goal.

An embodiment of the present invention will be described below with reference to the drawings.

I As shown in FIG. 4, the output of the AC power supply is boosted to a high voltage by the transformer P, and a DC bias is applied to the output of the transformer P by the variable DC power supply VE, which is applied to the electrode 6 of the corona charger 5. Ru.

The corona charger 5 is constructed by disposing six electrodes within a shield member 7, and is disposed in an electronic copying machine at a position facing the photoreceptor 8 with a transfer paper 9 interposed therebetween immediately after toner transfer. That is, this electrophotographic copying machine forms an electrostatic latent image by charging and exposing a photoreceptor, develops it, and transfers it to a transfer paper using a transfer charging device, and then separates the transfer paper from the photoreceptor. , are arranged according to their separation positions. The photoreceptor 8 is grounded, and the AC output of the transformer T2 is applied with a DC bias from the variable DC power supply VE between the electrode 6 and the photoreceptor 8, and the corona from the electrode 6 causes the transfer paper 9 to
is removed and separated. In this case, the humidity in the air is detected by the humidity sensing element 10. This moisture sensing element 10 is an element whose electrical resistance changes by absorbing moisture in the air. For example, thin grids are alternately pasted on a porous plastic plate and soaked with a hygroscopic liquid such as lithium chloride. used. Further, it is possible to use a sensor etc. by providing an electrode and a hygroscopic material film on a crystal oscillator and utilizing changes in the resonance state of the film. The AC amplifier 11 detects and amplifies this resistance change or resonant frequency change of the humidity sensing element 10, and the variable DC power supply VE is controlled by the output of this AC amplifier 11 to change the DC bias. In this way, by detecting the humidity in the air, controlling the DC bias, and adjusting the amount of positive and negative charges of the AC corona, it is possible to remove the static charge on the transfer paper 9 under any environmental conditions. Become. FIG. 5 shows another embodiment of the present invention, in which a control grid 12 is provided between the electrode 6 and the transfer paper 9, and a DC voltage is applied to the control grid 12 from a variable DC current E. The same effect as in the above embodiment can be obtained. As described above, according to the present invention, since the corona current is controlled by detecting the humidity in the air, it is possible to eliminate static electricity from the transfer paper without reducing the toner transfer efficiency in any environment. No longer affected by humidity.

[Brief explanation of the drawing]

Figures 1A and b are waveform diagrams for explaining the corona voltage and current of the charger for static elimination, Figure 2 is a circuit diagram showing a conventional charger for static elimination, and Figure 3 is the humidity and charging potential of the transfer paper. 4 and 5 are circuit diagrams each showing an embodiment of the present invention. D...Transformer, VE...Variable DC power supply, 5...Corona charger, 8...Photoreceptor, 9...Transfer paper , 10... Moisture sensing element, 12... Control grid.

Claims (1)

[Claims] 1. A corona charger that applies a corona discharge to the transfer paper, a power supply means that applies voltage to the corona charger, a detection means that detects humidity in the air, and an output of the detection means that charges the transfer paper and the corona charge. A charger for transfer and snow removal, comprising variable current means for controlling corona current between the electric appliance and the electric appliance.