KR100232847B1 - Apparatus and method for recognizing transfer environment in electronographic developing device - Google Patents

Abstract

In an electrophotographic developing apparatus, a transfer environment recognition unit for applying a transfer environment recognition voltage inversely proportional to the temperature of the transfer roller to a transfer roller to recognize transfer environment resistance of the transfer roller, and a visible image formed on the photosensitive drum are printed. By providing a transfer voltage generator that generates a transfer voltage in accordance with the transfer environment resistance to charge the paper to move toward the paper, it is possible to recognize the electronic environment resistance at high speed, and thus there is an advantage in that the transfer voltage control can be speeded up.

Description

Apparatus and Method for Recognizing Transfer Environment of Electrophotographic Developing Machine

The present invention relates to an apparatus and method for recognizing a transfer environment in an electrophotographic developing apparatus, and more particularly, to an electrophotographic developing apparatus for controlling a transfer voltage according to a transfer environment resistance. Transfer environment recognition of an electrophotographic development apparatus which speeds up the calculation of transfer environment resistance by controlling the transfer environment recognition voltage to be inversely proportional to the temperature measured by the temperature sensing sensor in order to accurately and quickly recognize transfer environment resistance. To provide a method.

In general, electrophotographic developing apparatuses used in copiers, laser printers, facsimiles, and the like, expose an image or image data obtained from a predetermined source to a photosensitive member to form an electro-static latent image, and then to a site where an electrostatic latent image is formed. A developer is applied to form a visible image, which is transferred onto a printing sheet, and then fixed to print a desired image.

On the other hand, such an electrophotographic developing apparatus is capable of printing a multicolored color image on a printing paper by providing a plurality of developers. Generally, YMCK (Yellow Magenta Cyan blacK), which is well known in a multicolor image forming apparatus, is used. As a result, multi-color electrophotographic development apparatus realizes multi-color using 4 color developer which adds black to 3 colors of yellow, magenta and cyan. have.

Today's electrophotographic development equipment is becoming the most common alternative for printing high-resolution images, and despite its high price, it is becoming more and more popular due to its superior printing performance such as high speed, beautiful printing, and excellent preservation. to be.

1 is an exemplary diagram schematically illustrating an internal structure of a general electrophotographic developing apparatus, and FIG. 2 is a flowchart illustrating an image forming method of a general electrophotographic developing apparatus.

In the general electrophotographic developing apparatus, as shown in FIG. 1, an organic photoconductive drum 20, an exposure apparatus 30, and various rollers 10, 40, 50, 70, 80, 90 interact with each other. As shown in Fig. 2, an image forming method comprising a charging step S10, an exposure step S20, a developing and transferring step S30, S50, and a fixing and antistatic step S60, S70 is performed. To form an image on the printing paper 110.

The transfer characteristics of the electrophotographic developing apparatus as described above should be applied to the transfer roller 70 with an appropriate voltage required by the electrophotographic developing apparatus to be transferred to an optimal state so that a transfer failure does not occur. When the transfer voltage V _t is low, electrostatic attraction generated in the transfer roller 70 is weak, and the toner is not adhered to the paper efficiently, so that transfer tremor occurs. On the other hand, when the transfer voltage is high, the photosensitive drum 20 The toner is reversely charged so that the toner does not adhere to the paper or the electrostatic attraction generated by the transfer roller 70 is strong, so that the toner is transferred onto the printing paper 110 before the printing paper 110 approaches the photosensitive drum 20, thereby causing an image. This is scattered. Therefore, the transfer failure can be prevented by applying an appropriate transfer voltage to the transfer roller 70, and the transfer efficiency can be improved accordingly.

Meanwhile, the transfer voltage V _t required by the system depends on the transfer environmental resistance between the transfer roller 70 and the photosensitive drum 20, the properties of the toner and the printing paper 110, and the like, in particular, FIG. 3B. As shown in FIG. 6, the proper transfer voltages V _t1 to V _t3 are greatly influenced by the transfer environment resistances R1 to R3, and the transfer environment resistance varies depending on the environment such as temperature and humidity.

Therefore, the electrophotographic developing apparatus according to the prior art performs the transfer environmental resistance measurement step (S40) to measure the transfer environmental resistance prior to performing the transfer step (S50) as shown in FIG. The appropriate transfer voltage is determined by comparison with the value.

Hereinafter, the transfer environmental resistance measurement step 40 of the electrophotographic developing apparatus according to the prior art will be described in more detail.

Usually, the transfer environment recognition voltage applied to recognize the transfer environment resistance of the transfer roller 70 is applied. V _thv , Current flowing through the transfer roller 70 I _thv When referred to, the transfer environmental resistance ( R _thv ) Can be easily calculated through Equation 1, which is a well-known current-voltage relationship.

In more detail, in order to measure the transfer environment resistance, a transfer environment recognition voltage is typically applied to the transfer roller 70 to transmit current detected from the transfer roller 70 through a current-voltage converter. Convert to voltage form. The voltage is changed to a value digitized through an analog to digital convertor (ADC), and then the current transfer environmental resistance is calculated to thereby transfer a transfer voltage proportional to the transfer environment resistance. It is common to take steps to apply to.

At this time, the higher the transfer environment recognition voltage applied to the transfer roller 70 in order to recognize the transfer environment resistance, the greater the degree of change in the transfer current according to the change in transfer environment resistance. As is well known, when the voltage is assumed to be a constant in the current-voltage relationship, the larger the voltage is, the larger the current slope with respect to the resistance is, which is due to an increase in the current variation with respect to the resistance variation.

In this way, the amount of current change according to the resistance change amount is large to reduce the influence of noise and to easily distinguish the analog-to-digital output, so that the accuracy and reliability of the recognition of the transfer environmental resistance can be ensured.

On the other hand, the transfer environmental resistance becomes smaller at higher temperatures and larger at lower temperatures. If the transfer environment recognition voltage applied to the transfer roller 70 to recognize the transfer environmental resistance is too large, the transfer roller at a high temperature state ( Since the transfer environmental resistance of the 70 is small, an overcurrent of the transfer roller 70 may flow through the photosensitive drum 20, thereby damaging the photosensitive drum 20.

Therefore, in order to prevent damage to the photosensitive drum 20, it is common to recognize the transfer environment resistance by controlling the transfer environment recognition voltage in multiple stages.

In other words, at first, a relatively low transfer environment recognition voltage is applied to read a rough transfer environment resistance, and when the transfer environment resistance is greater than or equal to a predetermined value, a relatively high transfer environment recognition voltage is again applied to correct the transfer environment resistance. We use a coarse-to-fine technique to recognize

However, according to the related art, since the operation for recognizing the transfer environmental resistance is performed in a multi-step in the case of a device that performs printing at high speed, it is a great obstacle to the speed of printing as it takes a lot of time to recognize the transfer environment. .

Accordingly, the present invention has been made in view of the problems of the prior art, and in order to accurately and quickly recognize the transfer environment, the transfer roller is variably controlled by controlling the transfer environment recognition voltage in inverse proportion to the temperature measured by the temperature sensor. The transfer environment of the electrophotographic developing apparatus which can control the transfer voltage at high speed by applying a transfer voltage to the transfer roller according to the transfer environment resistance in order to transfer the visible image onto the printing paper after obtaining the transfer environment resistance of the film. The purpose is to provide a recognition method.

1 is an exemplary diagram schematically illustrating an internal structure of a general electrophotographic developing apparatus;

2 is a flowchart of an image forming method of a general electrophotographic developing apparatus;

3 is a waveform diagram for explaining transfer efficiency according to transfer voltage.

4 is a block diagram showing a preferred embodiment of an apparatus for recognizing a transfer environment of an electrophotographic developing apparatus according to the present invention;

5 is a flowchart of a preferred embodiment of a method for recognizing a transfer environment of an electrophotographic developing apparatus according to the present invention.

<Description of Symbols for Main Parts of Drawings>

10: charging roller, 20: photosensitive drum

30: exposure apparatus, 40: feed roller,

50: developing roller, 60: regulating blade,

70: Champion roller 80: Heating roller,

90: crimping roller, 100: antistatic lamp,

110: printing paper.

In order to achieve the object of the present invention, a feature of the device of the present invention is a photosensitive drum in which an electro-static latent image is formed by exposure, and a phenomenon in which the latent electrostatic image is developed to form a visible image. An electrophotographic developing apparatus comprising a roller and a transfer roller for transferring the visible image to a printing sheet by charging with a transfer voltage;

A transfer environment recognition unit for recognizing a transfer environment resistance of the transfer roller by applying a transfer environment recognition voltage inversely proportional to the temperature of the transfer roller to the transfer roller; And

And a transfer voltage generator for generating the transfer voltage in accordance with the transfer environmental resistance to charge the visible image formed on the photosensitive drum to move toward the printing sheet.

In the feature according to the device of the present invention, the transfer environment recognition unit is located in the vicinity of the transfer roller temperature sensor unit for sensing a temperature;

A transfer environment recognition voltage generator for generating and outputting a transfer environment recognition voltage applied to the transfer roller in inverse proportion to an output of the temperature sensor unit to recognize transfer environment resistance of the transfer roller; And

And a transfer environment resistance calculator configured to detect a current flowing through the transfer roller after a predetermined time elapses after the transfer environment recognition voltage is applied to the transfer roller, and calculate the transfer environment resistance according to a current-voltage relationship. It is preferable.

A feature according to the method of the present invention is a photosensitive drum on which an electro-static latent image is formed by exposure, a developing roller which develops the electrostatic latent image to form a visible image, and charging by transfer voltage. A transfer environment recognition method of an electrophotographic developing apparatus comprising a transfer roller for transferring the visible image onto a printing sheet;

A temperature sensing step of sensing a temperature through a temperature sensor unit located around the transfer roller;

A transfer environment recognition voltage applying step of applying a transfer environment recognition voltage inversely proportional to the sensed temperature to the transfer roller to recognize the transfer environment resistance;

A transfer environment resistance calculating step of calculating a transfer environment resistance according to a current-voltage relationship by detecting a current flowing through the transfer roller after a predetermined time passes after the transfer environment recognition voltage is applied to the transfer roller; And

And a transfer voltage generation step of generating the transfer voltage in accordance with the transfer environmental resistance and applying the transfer voltage to a transfer roller to charge the visible image formed on the photosensitive drum to move toward the printing paper.

Hereinafter, a preferred embodiment of an apparatus for recognizing a transfer environment of an electrophotographic developing apparatus according to the present invention will be described with reference to FIG. 4.

Figure 4 is a block diagram showing a preferred embodiment of the transfer environment recognition apparatus of the electrophotographic developing apparatus according to the present invention.

According to a preferred embodiment of the apparatus for recognizing a transfer environment of an electrophotographic developing apparatus according to the present invention, as shown in FIG. 4, a photosensitive drum 20 having an electro-static latent image formed by exposure, and the electrostatic An electrophotographic developing apparatus including a developing roller (50) for developing a latent image to form a visible image, and a transfer roller (70) for transferring the visible image to the printing paper (110) by charging with a transfer voltage;

A transfer environment recognizing unit 200 for recognizing a transfer environment resistance of the transfer roller by applying a transfer environment recognition voltage inversely proportional to the temperature of the transfer roller to the transfer roller; And

And a transfer voltage generator 240 generating a transfer voltage according to the transfer environment resistance to charge the visible image formed on the photosensitive drum 20 to move toward the printing paper 110.

Here, the transfer environment recognition unit 200 is located in the vicinity of the transfer roller 70, the temperature sensor unit 210 for sensing the temperature;

A transfer environment recognition voltage generation unit generating and outputting a transfer environment recognition voltage applied to the transfer roller 70 in inverse proportion to the output of the temperature sensor 210 to recognize the transfer environment resistance of the transfer roller 70. 220; And

After the transfer environment recognition voltage is applied to the transfer roller 70, after a predetermined time has elapsed, a transfer environment resistance calculation unit 230 for detecting the current flowing through the transfer roller 70 to calculate the transfer environment resistance. ).

In addition, the temperature sensor unit 210 is preferably a thermistor, and the transfer environment recognition voltage generation unit 220 looks up the transfer environment recognition voltages for the temperature, respectively, by looking up the table for storing the lookup table ( 221); And

The lookup table 221 is configured to include a transfer environment recognition voltage search unit 222 for searching for the transfer environment recognition voltage corresponding to the temperature sensor unit 210.

An operation of the preferred embodiment of the transfer environment recognition apparatus of the electrophotographic developing apparatus according to the present invention configured as described above will be described with reference to FIG.

First, when the charging roller 10 charged by the high-voltage charging voltage rotates to evenly charge the photosensitive member formed on the outer circumferential surface of the photosensitive drum 20, the photosensitive drum 20 with charged light generated by the exposure apparatus 30 is charged. An electrostatic latent image to be printed is formed on the surface of the film. Thereafter, a developing roller 50 applied with a high development voltage forms a developer (eg, toner) on a surface of the photosensitive drum 20 on which the electrostatic latent image is formed to form a visible image.

At this time, when the tip of the printing paper 110 reaches the photosensitive drum 20 in a state of being adsorbed by the transfer roller 70, the printing paper to which the transfer roller 70 charged by the high-voltage transfer voltage transfers the visible image. Start of transfer on 110. At this time, the tip portion of the printing paper 110 is located at the point where the transfer starts, that is, the contact surface between the photosensitive drum 20 and the transfer roller 70.

When the transfer continues and the printing operation is completed in the order of exposure, development, and transfer, the transferred visible image is fixed to the printing paper 110 by the high temperature and pressure of the heating roller 80 and the compression roller 90. The print operation is completed.

Here, the core role of the transfer roller 70 is to move the visible image formed on the surface of the photosensitive drum 20 by the developer (for example, toner) toward the printing paper 110 as described above. The voltage applied to allow the toner to move toward the printing paper 110 through is called a transfer voltage, and the current is called a transfer current.

Thus, in order to measure the transfer environmental resistance, the charged potential of the photosensitive drum 20 should be constant, but as shown in FIG. 3C, the charged photosensitive drum 20 has its surface potential over time without any external factors. Since V _opc exhibits a dark attenuation phenomenon, a portion of the photosensitive drum 20 is charged to a constant electric potential so as to check the transfer environmental resistance.

At this time, the transfer environment recognition unit 200 according to the present invention recognizes the transfer environment resistance of the transfer roller 70 by applying a transfer environment recognition voltage inversely proportional to the temperature around the transfer roller 70 to the transfer roller. In addition, the transfer voltage generator 240 generates a transfer voltage according to the transfer environmental resistance in order to charge the visible image formed on the photosensitive drum 20 to move toward the printing paper 110.

The core of the present invention is to overcome the problem of the prior art, which takes a lot of time for the recognition of the transfer environment because the operation for recognizing the transfer environment is performed in a multi-step in the case of the device performing printing at high speed.

In other words, according to the calculation of the accurate transcriptional environmental resistance at high speed, the transcriptional environment recognition unit 200 performing a key function thereof will be described in more detail as follows.

First, the temperature sensor unit 210 detects the temperature of the transfer environment recognition unit 200 is located around the transfer roller 70.

At this time, a thermistor is used as the temperature sensor element.

Briefly describing the thermistor to help understand the temperature sensor device of the present invention, the thermistor is a semiconductor device which is mixed and sintered by combining various oxides such as manganese, nickel, copper, cobalt, chromium, iron, and the like. Changes in electrical resistance due to sensitive devices.

It is commonly used for temperature compensation of a temperature sensor or an electronic circuit as it is a negative resistance type device that exhibits a property of decreasing resistance when temperature rises, that is, negative resistance having a resistance value inversely proportional to temperature. Characteristics resistance of thermistor R _th Is as shown in equation (2).

here R ₀ , B Are the coefficients of resistance of the reference temperature and thermistor, respectively, T, T ₀ Are the temperatures obtained by converting the calculated temperature and the reference temperature into absolute temperatures, that is, absolute temperature values in units of K, respectively.

On the other hand, as another temperature sensor element means for sensing the temperature by physical thermal shrinkage, such as bi-metal (bi-metal) can also be mobilized for the present invention, if the means for sensing other temperature is It is well known that it can be easily modified and applied.

Thereafter, the transfer environment recognition voltage generation unit 220 applies a transfer environment recognition voltage applied to the transfer roller 70 to the output of the temperature sensor unit 210 to recognize the transfer environment resistance of the transfer roller 70. Generate it in inverse proportion and print it out.

As described above, various means may be employed to generate the transfer environment recognition voltage in inverse proportion to the output of the temperature sensor unit 210. However, in a preferred embodiment of the apparatus of the present invention, the ambient temperature of the transfer roller 70 is adopted. According to the output of the temperature sensor unit 210 through the transfer environment recognition voltage search unit 222 from the look-up table unit 221 which stores and maps the mapping relationship with the transfer environment recognition voltage, respectively. Search for the corresponding transfer environment recognition voltage.

Finally, after the transfer environment recognition voltage generator 220 applies the transfer environment recognition voltage retrieved from the lookup table unit 221 to the transfer roller 70, a predetermined time elapses to stabilize the transfer voltage. Next, the transfer environmental resistance calculator 230 detects a current flowing through the transfer roller 70 and calculates the transfer environment resistance based on a current-voltage relationship equation.

Hereinafter, a preferred embodiment of a method for recognizing a transfer environment of an electrophotographic developing apparatus according to the present invention will be described with reference to FIG. 5.

5 is a flowchart illustrating a preferred embodiment of a method for recognizing a transfer environment of an electrophotographic developing apparatus according to the present invention.

According to a preferred embodiment of the method for recognizing a transfer environment of an electrophotographic developing apparatus according to the present invention, as shown in FIG. 5, a photosensitive drum 20 having an electro-static latent image formed by exposure, and the electrostatic Recognizing a transfer environment of an electrophotographic developing apparatus including a developing roller 50 for developing a latent image to form a visible image, and a transfer roller 70 for transferring the visible image to the printing paper 110 by charging with a transfer voltage. In the method;

A temperature sensing step (S100) of sensing a temperature through a temperature sensor unit 210 positioned around the transfer roller 70;

A transfer environment recognition voltage applying step (S110) of applying a transfer environment recognition voltage inversely proportional to the sensed temperature to the transfer roller (70) to recognize the transfer environment resistance;

After the transfer environment recognition voltage is applied to the transfer roller 70, after a predetermined time elapses, a transfer for detecting the current flowing through the transfer roller 70 and calculating the transfer environment resistance according to a current-voltage relationship equation. Calculating environmental resistance (S120); And

Generating a transfer voltage according to the transfer environment resistance and applying the transfer voltage to the transfer roller 70 to charge the visible image formed on the photosensitive drum 20 to move toward the printing sheet; Is characteristic.

Referring to Figures 1, 2 and 4 of the performing procedure of the method for recognizing the transfer environment of the electrophotographic developing apparatus according to the present invention configured as described above are as follows.

First, while the charging roller 10 to which a high voltage of about several kilovolts (kV) is applied rotates, the surface of the photosensitive drum 20 is uniformly charged to several hundred volts (V) by corona discharge. The charging roller 10 is applied with a positive (+) potential or a negative (-) potential according to the characteristics of the image forming apparatus (S10).

The laser scanning unit 30 converts the image data signal to be printed into light and scans the same to the uniformly charged photosensitive drum 20. Accordingly, the photosensitive drum 20 has a different surface potential, thereby causing an electrostatic latent image ( Electro-static Latent Image) is generated (S20).

In this way, the photosensitive drum 20 in which the latent electrostatic image is generated is supplied to the developing roller 50 in which a charged developer (ie, toner) rotates due to friction between the supply roller 40 and the developing roller 50. At this time, the charged toner passes through the regulating blade 60 regulating the toner layer and is attached to the electrostatic latent image of the photosensitive drum 20 by electrostatic attraction, whereby the electrostatic latent image is developed as a visible image (S30).

The toner that forms a visible image on the photosensitive drum 20 is transferred onto the printing paper 110 passing between the transfer roller 70 and the photosensitive drum 20, wherein the toner attached to the photosensitive drum 20 is The electrostatic attraction generated by the transfer roller 70 charged with the opposite polarity is transferred onto the printing paper 110 passing therebetween (S50).

The toner image transferred onto the printing paper 110 is fixed to the printing paper 110 by heat and pressure while passing through the heating roller 80 and the compression roller 90 and discharged (S60).

In addition, after the toner is transferred onto the printing paper 110, the photosensitive drum 20 is discharged by the light generated from the antistatic lamp 100, and is again charged by the charging roller 10. The image forming process is completed (S70, S80).

In the image forming method of a general electrophotographic developing apparatus as described above, the present invention measures the transfer environmental resistance and accordingly applies a transfer voltage to the transfer roller 70 to capture a visible image formed on the photosensitive drum 20. It is directly related to what is intended to be charged to move toward the printing paper, which will be described below.

First, in the temperature sensing step (S100) according to the present invention, the temperature is sensed through the temperature sensor unit 210 located around the transfer roller 70. Here, the temperature sensor unit 210 uses a thermistor.

Thereafter, in the step of applying a transfer environment recognition voltage (S110), a transfer environment recognition voltage inversely proportional to the sensed temperature is applied to the transfer roller 70 to recognize the transfer environment resistance.

Subsequently, in the step of calculating a transfer environmental resistance (S120), after the transfer environment recognition voltage is applied to the transfer roller 70, a current flowing through the transfer roller 70 is detected by a current after a predetermined time elapses. The transfer environmental resistance is calculated according to the relationship.

Accordingly, in the transfer voltage generation step (S130), the transfer voltage is generated according to the transfer environment resistance and applied to the transfer roller 70 to charge the visible image formed on the photosensitive drum 20 toward the printing paper. Let's do it.

Here, the step of applying the transfer environment recognition voltage (S110) is performed based on the ambient temperature of the transfer roller 70 according to the detected temperature from the storage medium storing the lookup table of the mapping relationship with the transfer environment recognition voltage, respectively. It is desirable to retrieve the corresponding transfer environment recognition voltage.

Since the present invention has been described through the preferred embodiments of the present invention, in view of the technical difficulty aspects of the present invention, a person having ordinary skill in the art may easily make other modifications from other embodiments of the present invention. Therefore, it is apparent that all embodiments and modifications cited in the above description belong to the claims of the present invention.

As described in detail above, in an electrophotographic developing apparatus; A transfer environment recognition unit for recognizing a transfer environment resistance of the transfer roller by applying a transfer environment recognition voltage inversely proportional to the temperature of the transfer roller to the transfer roller; And a transfer voltage generator for generating the transfer voltage according to the transfer environment resistance to charge the visible image formed on the photosensitive drum to move toward the printing paper, the electronic environment resistance can be recognized at high speed. As such, there is an advantage in that the transfer voltage control can be speeded up.

Claims (6)

A photosensitive member on which an electro-static latent image is formed by exposure, a developer developing a latent electrostatic image to form a visible image, and a transfer of the visible image to printing paper by charging with a transfer voltage. An electrophotographic developing apparatus including a body; A transfer environment recognition unit configured to recognize a transfer environment resistance of the transfer body by applying a transfer environment recognition voltage inversely proportional to the temperature of the transfer body to the transfer body; And And a transfer voltage generator for generating the transfer voltage according to the transfer environment resistance in order to charge the visible image formed on the photosensitive member to move toward the printing paper. The method of claim 1, wherein the transcription environment recognition unit, A temperature sensor unit positioned around the transfer body and sensing a temperature; A transfer environment recognition voltage generation unit generating and outputting a transfer environment recognition voltage applied to the transfer body in inverse proportion to an output of the temperature sensor unit to recognize transfer environment resistance of the transfer body; And After the transfer environment recognition voltage is applied to the transfer body, after a predetermined time has elapsed is configured to detect the current flowing in the transfer body and calculates the transfer environment resistance in accordance with the current-voltage relationship equation A transfer environment recognition apparatus for an electrophotographic developing apparatus, characterized in that. The method of claim 2, wherein the transfer environment recognition voltage generator, A look-up table unit which stores a look-up table of the transfer environment recognition voltages for the temperature, respectively; And And a transfer environment recognition voltage retrieval unit for retrieving the transfer environment recognition voltage corresponding to the temperature sensor unit from the look-up table unit. The apparatus of claim 1, wherein the temperature sensor unit is a thermistor. A photosensitive member on which an electro-static latent image is formed by exposure, a developer developing a latent electrostatic image to form a visible image, and a transfer of the visible image to printing paper by charging by a transfer voltage. A transfer environment recognition method of an electrophotographic developing apparatus including a body; A temperature sensing step of sensing a temperature through a temperature sensor unit located around the transfer member; A transfer environment recognition voltage applying step of applying a transfer environment recognition voltage inversely proportional to the sensed temperature to the transfer body to recognize the transfer environment resistance; A transfer environment resistance calculating step of calculating a transfer environment resistance according to a current-voltage relationship by detecting a current flowing through the transfer body after a predetermined time has passed after the transfer environment recognition voltage is applied to the transfer body; And And a transfer voltage generation step of generating a transfer voltage according to the transfer environmental resistance and applying the transfer voltage to a transfer member to charge the visible image formed on the photosensitive member to move toward the printing paper. Environmental awareness method. 6. The method of claim 5, wherein the temperature sensor unit is a thermistor.

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