JPH03225384A - Transfer control method - Google Patents

Abstract

PURPOSE:To obtain a recording image having an excellent recording density and excellent resolution regardless of a change in environmental temp. and humidity by detecting humidity and controlling a voltage applying on a transfer roller according to the humidity. CONSTITUTION:A sensor 11 detecting the humidity of a transfer part is provided near a transfer position. A transfer bias voltage applied on the transfer roller 9 is adjusted on a control circuit 12, according to the humidity detected by the sensor 11. A fixed high transfer bias voltage is applied under a low humidity environment, and the transfer bias voltage is switched to a low value when environmental humidity is a fixed one or above, so that a tolerance recording density and excellent recording resolution can be held. Especially, it is effective when toner having low electric resistance such as conductive toner is used. When the environmental humidity is high and the specific resistance of a recording sheet is low, an effect is increased as a quantity that a current by the voltage added as the transfer bias voltage flows into toner is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field to Which the Invention Pertains) The present invention relates to a transfer control method in an electrophotographic recording apparatus that transfers a toner image on a photoreceptor to a recording paper using a transfer roller.

(Prior Art) As a means of transferring electrophotographic records, there is a corona transfer method. In the corona transfer method, ions are generated by applying a voltage of several kilovolts to a thin wire, and the adsorption of the ions increases the potential on the recording paper side, thereby transferring the toner to the recording paper. The corona transfer method has the advantage of being able to transfer without contacting the photoreceptor drum, but
There are problems such as requiring a power source of several kilovolts and generating ozone, a toxic gas.

Further, as a transfer method that does not use high voltage, there is a roller transfer method. The applied voltage may be one order of magnitude lower than that of corona transfer. The roller transfer method uses a conductive rubber roller to transfer the toner image onto the recording paper by continuously applying a predetermined voltage while the recording paper is in close contact with the photoreceptor drum on which the toner image is formed. .

(Problems to be Solved by the Invention) The present inventors have confirmed that when using the roller transfer method described above, the recording resolution tends to decrease as the environmental conditions of the electrophotographic recording apparatus, particularly humidity, increase. That is,
FIG. 2 illustrates the relationship between environmental humidity and transfer recording resolution when the transfer bias voltage applied to the transfer roller is constant regardless of environmental changes, taking the case where the environmental temperature is 30° C. as an example. As shown in the figure, when the transfer bias voltage (V) is constant, the recording resolution (a) tends to decrease as the environmental humidity (b) increases.

This is because when the environmental humidity increases, the volume resistance and surface resistance of the recording paper decrease, so for a constant transfer bias voltage, the toner is once transferred to the recording paper, resulting in a low resistance. Charge is injected through the recording paper and the voltage increases, making it the same potential as the recording paper. Then, it is attracted to the photoreceptor drum again by the electrostatic force, adheres to the photoreceptor drum, charges are injected by the photoreceptor drum, the potential decreases, and the photoreceptor is again attracted to the recording paper by the electrostatic force.

Due to the so-called jumping phenomenon in which this phenomenon is repeated, the toner transfer position deviates from the initial position of the visible image on the photoreceptor drum, resulting in a decrease in recording resolution.

In addition, Figure 3 shows the relationship between the transfer bias voltage applied to the transfer roller, recording density (c), and recording resolution (a) at 35°C.
, plotted under 85% environmental conditions.

As shown in the figure, the recording density (c) becomes thinner as the transfer bias voltage becomes lower.

However, there is a permissible value for the recording density (c), and in the figure, for example, if it is 100 V or more, recording is considered to be good.

On the other hand, the recording resolution (a) tends to improve as the transfer bias voltage decreases, as shown in the figure.

This is because the transfer bias voltage is low even when the resistance of the recording paper is low in a high temperature, high humidity environment, so less charge is injected into the toner transferred from the photoreceptor drum to the recording paper, and the polarity of the charge on the toner increases. This is because there is no reversal and the photosensitive drum does not attract the photosensitive drum again, and the jumping phenomenon does not occur or occurs only a very small number of times.

(Object of the Invention) In view of the circumstances explained in FIGS. 2 and 3 above, the present invention aims to provide a transfer control method that prevents changes in transfer recording resolution due to environmental conditions during running of recording paper. purpose.

(Means for Solving the Problems) In order to achieve the above object, the present invention detects and outputs humidity in an electrophotographic recording apparatus that transfers a toner image on a photoreceptor to recording paper using a transfer roller. The present invention is characterized in that the voltage applied to the transfer roller is controlled depending on the transfer roller.

(Function) By using the above transfer control method, the recording resolution did not deteriorate significantly even when the environmental humidity changed significantly, and it was possible to record images without any problems in practical use.

(Example) FIG. 1 shows a configuration diagram of the main parts of a transfer section for carrying out the present invention. 2 is a corona charger, 3 is a charged charge, 4 is a scanner that irradiates a light image onto the photoreceptor drum 1, 5 is an electrostatic latent image, 6 is a developer, and 7 is a visible toner. Statue, 8 is recording paper,
Reference numeral 9 uses conductive rubber, has contacts, and is insulated from the main body, and is driven by a drive mechanism (not shown) to the photosensitive drum 1
10 is a toner image transferred onto the recording paper 8, and these are known members or the like.

This embodiment includes a sensor 11 that is disposed near the transfer position and detects the humidity of the transfer section, and a control circuit 12 that switches the transfer bias voltage applied to the transfer roller 9 according to the level of humidity detected by the sensor. Features.

The control circuit 12 adjusts the transfer bias voltage applied to the transfer roller 9 according to the humidity detected by the sensor 11, and in a low humidity environment, by applying a constant high transfer bias voltage, high recording density can be achieved. When the environmental humidity exceeds a certain level, by switching the transfer bias voltage to a lower value, it is possible to maintain recording density within an acceptable range and good recording resolution.

As a result of examining the conditions necessary for a recorded image based on various recording examples, as shown in Figure 3, the permissible range is a recording density of 1.2 or more, and the recording resolution is converted to the amount of spread. It is thought to be less than 1.3. The spread amount of the recording resolution is the line width on the recording rain relative to the electrical recording signal, and ideally the spread amount is 1, and the larger the value, the louder the resolution. As a result of determining voltage switching conditions for the control circuit 12 corresponding to this value, the switching conditions were determined to be 150 V at normal humidity and 100 V at 35° C. and 85%.

The transfer control method of this embodiment described above is particularly effective in an electrophotographic recording apparatus that uses toner having a low electrical resistance value such as conductive toner. In other words, since the resistance value of the toner is low, when the environmental humidity increases and the specific resistance value of the recording paper becomes low, the amount of current flowing into the toner due to the voltage applied as a transfer bias voltage through the recording paper is large. Highly effective.

This is because the more current that flows into the toner, the more likely the polarity reversal of the charges on the toner occurs, and the greater the effect of preventing polarity reversal when the transfer bias voltage is lowered.

Example In FIG. 1, the resistance value of the toner used is 10.
It has been confirmed that it is particularly effective in the range of about 3 to 1010 Ωl.

In the embodiment illustrated here, the transfer bias voltage is switched in two stages depending on the level of environmental humidity, but it is possible to detect the environmental humidity more precisely.
A method of finely switching and adjusting the transfer bias voltage in three or more stages according to the detected value is also easily considered.

(Effects of the Invention) As explained above, the present invention controls the transfer bias voltage applied to the transfer roller according to the environmental temperature and humidity, so that good recording density and resolution can be achieved despite changes in the environmental temperature and humidity. There is an advantage that recorded images can be obtained.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of the main parts of a transfer section for carrying out the present invention,
FIG. 2 is a diagram showing actual measurement results of environmental humidity and recording resolution, and FIG. 3 is a diagram showing the relationship between transfer bias voltage, recording density, and recording resolution. 1... Photosensitive drum, 2... Corona charging, 3
...Charged charge, 4...Light image irradiation, 5...Electrostatic latent image, 6...Developer, 7...Visible image of toner, 8...Recording paper, 9...・Transfer roller,
10... Toner image, 11... Sensor, 12...
control circuit.

Claims (1)

[Claims] A transfer control method in an electrophotographic recording device that transfers a toner image on a photoreceptor to a recording paper using a transfer roller, the method comprising detecting humidity and controlling the voltage applied to the transfer roller according to the humidity. .