KR101838536B1 - Image forming apparatus and transfer power control method thereof - Google Patents

Abstract

An image forming apparatus according to the present invention includes: a transferring section for transferring an image formed on a photoreceptor to a transfer medium; A power supply unit for supplying a transfer power to the transfer unit; And a transfer power source control unit for controlling transfer power supplied from the power source unit to the transfer unit, wherein the transfer source power control unit applies an initial pre-discharge current to the transfer unit at a predetermined interval before the image is transferred to the transfer medium And controls the power supply unit to apply the set target voltage to the transfer unit while the image is transferred to the transfer medium.

Description

[0001] The present invention relates to an image forming apparatus and a transfer power control method thereof,

To an image forming apparatus for controlling a transfer power for transferring an image formed on a photoreceptor to a transfer medium.

The process of forming an image on a print medium in the image forming apparatus can be described as follows. First, a photoconductor is exposed to form an electrostatic latent image, and then a developer is supplied to develop an image. That is, the developer particles charged on the surface of the photoconductor are distributed according to the form of the electrostatic latent image. Then, the image formed on the photosensitive member is transferred to the print medium. That is, the developer particles on the surface of the photoconductor are transferred to the printing medium. Finally, the image forming process is terminated by heating and pressing the developer transferred to the printing medium to fix it on the printing medium.

The process of transferring the image formed on the photosensitive member to the print medium in the above process will be described in detail as follows. The image formed on the photoreceptor may be directly transferred to a print medium such as paper to be finally formed or transferred to an intermediate transfer body first, and then secondary transferred to the print medium from the intermediate transfer body. Hereinafter, all the objects to which an image is transferred are referred to as a transfer medium. The developer particles present on the surface of the photoreceptor or the intermediate transfer member are transferred to the transfer medium according to the electrostatic force by applying a voltage having a polarity opposite to that of the charged electrode to the transfer medium. For example, if the developer particles forming an image on the surface of the photoreceptor or the intermediate transfer member are charged with a negative (-) electrode, when a positive voltage is applied to the opposite side of the photoreceptor or the intermediate transfer member with respect to the transfer medium, The developer particles migrate to the surface of the transfer medium.

At this time, as a method for applying a voltage to the opposite side of the transfer medium, a method of applying a constant current (hereinafter, referred to as CC) method in which a constant current is applied to a transfer member such as a transfer roller located on the opposite side of the transfer medium, Constant Voltage (CV) method can be used. Among the above two methods, the constant current method has an advantage of being able to cope with a longitudinal change such as a change of a load of the whole system of the image forming apparatus and a resistance of a transfer medium, It is difficult to cope with a temporary change such as a change in density of an image. On the contrary, in the case of the constant voltage method, a constant voltage can be maintained in spite of frequent and small change in resistance, which is advantageous in coping with temporal resistance change, but is not suitable for a change in resistance over time.

It is an object of the present invention to provide a transfer power control method of an image forming apparatus capable of taking all the advantages of a constant current system and a constant voltage system in transferring an image to a transfer medium.

According to an aspect of the present invention, there is provided an image forming apparatus including: a transfer unit transferring an image formed on a photosensitive member to a transfer medium; A power supply unit for supplying a transfer power to the transfer unit; And a transfer power source control unit for controlling transfer power supplied from the power source unit to the transfer unit, wherein the transfer source power control unit applies an initial pre-discharge current to the transfer unit at a predetermined interval before the image is transferred to the transfer medium And the control unit controls the power unit to apply the set target voltage to the transfer unit while the image is transferred to the transfer medium.

At this time, the transfer power source control unit calculates the system load of the image forming apparatus using the output voltage of the power source unit, which is measured when the power source unit applies a constant current to the transfer unit, and determines the initial pre- .

The transfer power control unit may include: a voltage measuring unit for measuring an output voltage of the power supply unit; And a pre-current control unit for controlling the entire pre-current to be applied to the transfer unit by the power unit according to the output voltage of the power unit measured by the voltage measuring unit.

At this time, the pre-regulating current controller may control the entire pre-current to be applied to the transfer portion by the power source portion so that the output voltage of the power source portion maintains the target voltage while the image is transferred to the transfer medium.

Also, at this time, the full-dictionary control unit calculates the feedback correction rate using the output voltage of the power source unit and the target voltage measured while the image is transferred to the transfer medium, and when the size of the feedback correction rate is out of a certain range The value obtained by adding the integral part of the value obtained by multiplying the current full dictionary dictionary by the feedback correction factor to the current total dictionary dictionary can be set as a new full dictionary dictionary.

At this time, the full dictionary control unit divides the value obtained by subtracting the output voltage of the power source unit measured while the image is transferred from the target voltage by the sum of the target voltage and the output voltage of the power source unit measured while the image is transferred The result of multiplying by a constant constant can be determined by the feedback correction rate.

Also, at this time, the full dictionary control unit may adjust the degree of the feedback control by adjusting the constant value.

Meanwhile, the transfer power source control unit measures the output voltage of the power source unit by a predetermined number of times while the power source unit applies the initial pre-discharge current to the transfer unit in a predetermined interval before the image is transferred to the transfer medium, The average value of the values that have been set can be set as the target voltage.

Alternatively, the transfer power source control unit may set the target voltage in a period before an image is transferred to the transfer medium after the transfer medium is drawn into the transfer unit.

According to another aspect of the present invention, there is provided a method of controlling transfer power of an image forming apparatus, comprising: determining an initial pre-discharge; Setting an output voltage of the power source unit, which is measured when the power source unit applies the determined initial pre-discharge current to the transfer unit at a predetermined interval before the image is transferred to the transfer medium, to a target voltage; And transferring the image to the transfer medium by applying the target voltage to the transfer unit.

At this time, the step of determining the initial pre-current flow may include calculating the system load of the image forming apparatus using the output voltage of the power source unit measured when the power source unit applies a constant current to the transfer unit, I can decide the dictionary flow.

The step of transferring the image may include the steps of: measuring the output voltage of the power source while the image is transferred to the transfer medium by applying a full pre-current to the transfer unit from the power source unit; And adjusting a full-length pre-current applied to the transfer unit by the power source unit so that an output voltage of the power source unit measured while the image is transferred maintains the target voltage.

Also, the step of adjusting the full-length dictionary stream may include calculating a feedback correction rate using the output voltage of the power source unit and the target voltage measured while the image is transferred; And setting a value obtained by adding the integer part of the value obtained by multiplying the current full dictionary dictionary and the feedback correction factor to the current total dictionary dictionary as a new full dictionary dictionary if the size of the feedback correction factor is out of a certain range .

The calculating of the feedback correction factor may further include calculating a value obtained by subtracting the output voltage of the power source unit measured while the image is transferred from the target voltage from the target voltage and an output voltage of the power source unit measured while the image is transferred It is possible to determine the result of multiplying the constant value by the feedback correction ratio.

Also, at this time, the degree of the feedback control can be adjusted by adjusting the constant value.

Meanwhile, the step of setting the target voltage may include the step of setting the output voltage of the power source unit by a predetermined number of times while the power source unit applies the initial pre-discharge current to the transfer unit during a predetermined constant interval before the image is transferred to the transfer medium After the measurement, the average value of the measured values can be set as the target voltage.

Alternatively, the predetermined period may be a period before an image is transferred to the transfer medium after the transfer medium is drawn into the transfer portion.

According to the above description, the target voltage is set by applying the transfer power source to the transfer portion by a constant current method in a predetermined constant interval before the image is transferred to the transfer medium, and while transferring the image to the transfer medium, It is possible to appropriately cope with both a temporal change such as a change in the system load of the image forming apparatus and a change in the transfer medium resistance and a temporal change such as a change in density of the transferred image. That is, the advantages of both the constant current method and the constant voltage method can be all taken.

Also, the constant-current-mode power supply device is controlled by firmware to maintain the output voltage of the power supply device at a target voltage, thereby realizing a constant voltage method without additionally providing a constant-voltage power supply device.

1 is a block diagram showing an image forming apparatus according to an embodiment of the present invention.
FIG. 2 is a diagram specifically showing each configuration of an image forming apparatus according to an embodiment of the present invention.
FIG. 3 is a graph showing changes in current and voltage with time in the case of performing transfer power control in an image forming apparatus according to another embodiment of the present invention.
4 is a block diagram showing a detailed configuration of a transfer power source control unit 150 of an image forming apparatus according to another embodiment of the present invention.
5 to 8 are flowcharts for explaining a transfer power control method according to another embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In order to more clearly describe the features of the embodiments, a detailed description will be omitted with respect to the matters widely known to those skilled in the art to which the following embodiments belong.

FIG. 1 is a block diagram showing an image forming apparatus according to an embodiment of the present invention, and FIG. 2 is a diagram specifically showing each configuration of an image forming apparatus according to an embodiment of the present invention. 1 and 2, an image forming apparatus according to an exemplary embodiment of the present invention includes a development unit 110, a transfer unit 120, a fusing unit 130, A power supply unit 140, and a transfer power control unit 150, as shown in FIG. The transfer unit 120 may include a primary transfer unit 120a and a secondary transfer unit 120b.

When the image forming apparatus according to an embodiment of the present invention receives image data from the outside, the developing unit 110 develops the image. More specifically, when light is scanned on the photoreceptors 115 to 118 in the exposure units 111 to 114, an electrostatic latent image is formed on the photoreceptors 115 to 118, and a developer containing toner developer is supplied, developer particles are attracted to the surfaces of the photoconductors 115 to 118 to form an image. In FIG. 2, four exposure units 111 to 114 and four photoconductors 115 to 118 are shown in FIG. 2. In general, in the image forming apparatus for forming a color image, CMYK, ie, cyan, magenta, Yellow, and black, respectively, and the present invention is not limited thereto.

The image formed on the photoreceptors 115 to 118 is transferred to the intermediate transfer belt 127 from the primary transfer portion 120a. Images for colors of cyan, magenta, yellow and black can be sequentially transferred to the intermediate transfer belt 127 circulated by the intermediate transfer rollers 125 and 126 to complete one color image. The color image formed on the intermediate transfer belt 127 is transferred again to the print medium 102 supplied from the secondary transfer portion 120b. Although the indirect transfer method in which an image is primarily transferred from the photoreceptors 115 to 118 to the intermediate transfer belt 127 and then is secondarily transferred from the intermediate transfer belt 127 to the print medium 102 is exemplified , Or a direct transfer method in which an image is transferred directly from a photoreceptor to a print medium. In addition, the intermediate transfer belt 127 and the print medium 102, which are objects to which an image is to be transferred, can be referred to as a transfer medium as a whole.

The print medium 102 to which the image has been transferred is conveyed along the print medium conveyance path 106 to the fusing unit 130 and heated and pressed by the fusing rollers 131 and 132. [ Thus, the image is fixed on the print medium 102, and the image forming process is thus ended.

The transfer process performed by the transfer unit 120 during the image forming process will be described in detail. The primary transfer rollers 121 to 124 receive the transfer power from the power supply unit 140 to transfer the image formed on the photoreceptors 115 to 118 to the intermediate transfer belt 127, The transfer voltage is applied to the particles. That is, when the voltages of the developer particles on the surfaces of the photoreceptors 115 to 118 are applied to the primary transfer rollers 121 to 124 at the opposite polarity to the charged poles, the developer particles on the surfaces of the photoreceptors 115 to 118 And moves to the intermediate transfer belt 127 by electrostatic force. The secondary transferring unit 120b also receives the transferring power from the power supply unit 140 to the secondary transferring roller 128 on the same principle to transfer the developer particles present on the intermediate transferring belt 127 to the opposite polarity The developer particles are moved from the intermediate transfer belt 127 to the surface of the print medium 102 conveyed through the print medium conveyance path 106. [ However, when the magnitude of the transfer voltage applied to the charged developer particles is not proper, poor transfer or re-transfer may occur. If the size of the transfer voltage is less than the size required for proper transfer, all developer particles will not migrate to the transfer medium and some will remain on the photoreceptor surface, which is called incomplete transfer. Conversely, if the magnitude of the transfer voltage is larger than the size required for proper transfer, some of the developer particles transferred to the transfer medium are charged with the polarity of the transfer voltage and moved to the surface of the photoreceptor again by attraction.

Meanwhile, a method of supplying the transfer power from the power supply unit 140 to the transfer unit 120 includes a constant current (CC) method of supplying a constant current and a constant voltage (CV) method of supplying a constant voltage.

The characteristics of the constant current method are as follows. When an image is transferred by a constant current method, a current to be applied is kept constant, and therefore, a bias shift of a current density occurs due to a change in resistance due to a change in density of a transferred image. That is, assuming that the same full-length dictionary current is applied, a bias shift of the current density occurs between the low-density image area having a low image density and the high-density image area having a high image density, The current density in the region becomes higher. At this time, the higher the ratio of the area where the image pattern exists in the total area, the higher the density of the image. In addition, the solid pattern area means a full image pattern without blanks. Therefore, incomplete transfer can occur in the high-density image area if the full-length dictionary image is set in the low-density image area. Conversely, if the full dictionary stream is set in the high-density image area, reverse transfer may occur in the low density image area. In other words, when the same full-length dictionary is applied to the low-density image area and the high-density image area, the high-density image area receives a transfer voltage higher than the low-density image area due to high resistance, There is a problem that steps are generated. On the other hand, the constant current method has an advantage that it can appropriately cope with a time-dependent change such as a resistance of a system part of an image forming apparatus or a transfer medium.

The characteristics of the constant voltage method are as follows. In the case of the constant voltage system, the transfer voltage is kept constant regardless of the change of the resistance of the system part or the transfer medium of the image forming apparatus. Therefore, if the resistance of the system part of the image forming apparatus or the transfer medium itself is lowered, Conversely, if the resistance of the system part of the image forming apparatus or the transfer medium itself increases, incomplete transfer is likely to occur. However, since the constant current density is kept constant despite the density change of the image, the constant voltage method is advantageous in that the concentration step according to the density change of the image does not occur.

The transfer power source control unit 150 of the image forming apparatus according to the embodiment of the present invention controls the power source unit 140 to use the constant current method and the constant voltage method in combination. Specifically, the transfer power control unit 150 controls the power supply unit 140 to apply a constant current to the transfer unit 120 in a constant current mode to measure the system load of the image forming apparatus and determine an appropriate initial pre-current flow based on the system load. Then, the power supply unit 140 is controlled to apply the pre-charge current in the constant current mode in a certain period before transferring the image, and the output voltage of the transfer unit to be measured is determined as the target voltage. At this time, the predetermined section before transfer of the image to be subjected to the target voltage may be a predetermined section immediately before transfer of the image to the intermediate transfer belt 127 in the case of the primary transfer, and may be a transfer section in the case of the secondary transfer, It may be a period from when the print medium 102 is pulled into the secondary transfer portion 120b to when the transfer of the image from the print medium 102 is started. Subsequently, when image transfer starts, the transfer source power controller 150 controls the power source unit 140 to apply the determined target voltage in a constant voltage method. By determining the target voltage in the constant current method before transferring the image by using the initial pregroove determined based on the system load of the image forming apparatus measured by the constant current method as described above, it is possible to appropriately cope with the change of the environment, the change in resistance of the transfer medium, The target voltage can be applied by the constant voltage method at the time of image transfer so that the concentration step does not occur even when the density of the image changes.

FIG. 3 is a graph showing changes in current and voltage with time in the case of performing transfer power control in an image forming apparatus according to another embodiment of the present invention. Referring to FIG. 3, a transfer power control method in an image forming apparatus according to another embodiment of the present invention will be described in detail.

To transfer power control unit 150 in the interval of the first t ₁ ~ t ₂ has a power supply 140 is controlled to apply a constant current to the constant current mode to the transfer unit 120, and this time use the output voltage of the power source 140 is measured The system load of the image forming apparatus is calculated. As shown in FIG. 3 (b), since the output voltage of the power supply unit 140 is not constant within the interval, it can be measured several times and the average value thereof can be used. For example, the system load of the image forming apparatus can be calculated by measuring the output voltage 25 times at 4 ms intervals and using the average value. Once the system load of the image forming apparatus is obtained, the initial pre-flow can be determined to an appropriate value based on the system load.

The output voltage of the initial former transfer power control unit 150 in the period of t ₃ ~ t ₄ after determining the dictionaries controls the power supply 140 to apply a predetermined initial pre dictionaries to the transfer unit 120, and wherein the power supply 140 of the Can be measured and determined as the target voltage. The period t ₃ to t ₄ for determining the target voltage may be a predetermined period immediately before the image is transferred to the intermediate transfer belt in the case of primary transfer in which an image is transferred from the photoreceptor to the intermediate transfer belt. An appropriate target voltage according to the system environment immediately before image transfer can be set by determining the target voltage in the constant current method in a section immediately before the start of image transfer. That is, even when the load or the like changes due to the change of the system environment in the interval of t ₂ to t ₃ , the target voltage reflecting the environmental change can be determined by determining the target voltage by the constant current method in the interval of t ₃ to t ₄ .

Alternatively, the intermediate transfer section of the belt t ₃ ~ in the case of the secondary transfer to transfer the image to the print medium from t ₄ is one period of until the printing medium is started, the transfer of the image to the print medium from after the inlet to the transfer unit . For example, it may be a section from the time when the leading end of the sheet, which is a print medium, is drawn into the transfer section to the time when the image is transferred for the first time on the paper. Therefore, an appropriate target voltage reflecting the resistance of the print medium can be determined. On the other hand, as in the case of measuring the system load, since the output voltage of the power supply unit 140 is not constant within the interval of t ₃ to t ₄ , it can be measured several times and the average value thereof can be determined as the target voltage. For example, after measuring the output voltage 5 times at 4ms intervals, the root mean value can be determined as the target voltage. Then transfer the power controller 150 in the period of t ₄ ~ t ₅ may be controlled by a power source 140 for applying a target voltage determined in the transfer unit 120 at a constant voltage scheme, perform the transfer of the image.

At this time, in order to use the constant current system and the constant voltage system in combination, the power supply unit 140 includes both a constant current power supply system and a constant voltage system power supply system. Under the control of the transfer power control unit 150, May be selectively used. Alternatively, the power supply unit 140 may include only a constant current type power supply unit, and may implement a constant voltage method by controlling the entire pre-current according to the control of the transfer power control unit 150. When the constant current method is implemented by controlling the entire pre-stream current, the transfer source power controller 150 is provided with firmware for controlling all the pre-eccentric currents and can perform control through the firmware. An embodiment in which only the constant current type power supply unit is provided in the power supply unit 140 and the constant voltage method is implemented by adjusting the full-range current in the firmware is described in detail with reference to FIG.

4 is a block diagram showing a detailed configuration of a transfer power source control unit 150 of an image forming apparatus according to another embodiment of the present invention. Referring to FIG. 4, the transfer power source control unit 150 in the image forming apparatus according to another embodiment of the present invention may include a voltage measuring unit 152 and a full dictionary control unit 154. The method of determining the initial pre-current and the target voltage is the same as that described above with reference to Figs. 1 to 3. Therefore, only the concrete method of applying the target voltage in the constant voltage manner through the control of the full dictionary flow will be described below.

The voltage measuring unit 152 can measure the output voltage of the power supply unit 140 of the image forming apparatus. The full dictionary control unit 154 may perform the feedback control so that the output voltage of the power supply unit 140 maintains the target voltage while the image is transferred. When the image transfer to the transfer medium is started, the voltage measuring unit 152 measures the output voltage of the power supply unit 140 in the section in which the image is transferred, and the full-dictionary control unit 154 performs the feedback control using the output voltage can do. At this time, since the output voltage of the power supply unit 140 changes with time, it may be measured a predetermined number of times and the average value thereof may be used. For example, you can measure the output voltage 10 times at 4ms intervals and use the average value. When the output voltage of the power supply unit 140 is measured, the feedback correction rate for feedback control can be calculated using the following equation.

V _t is the target voltage by the formula, V is the output voltage, C of the power supply section 140, the measurement of the transfer of an image refers to a fixed constant, and K is a feedback correction rate. C is a constant that can determine the degree of feedback control. If the value is large, the feedback control becomes sensitive because it is sensitive to a small change in the output voltage. Conversely, if the value is small, the degree of feedback control becomes weak. The value of C can be set, for example, to 1.5.

After calculating the feedback correction rate, it is determined whether or not the magnitude of the feedback correction rate is within a certain range. If the magnitude of the feedback correction rate is outside the predetermined range, the feedback control of the previous dictionary is performed. For example, if the magnitude of the calculated feedback correction ratio is smaller than 0.03, the current full dictionary flow is maintained as it is, and if it is 0.03 or more, the power supply unit 140 is controlled to apply a new full dictionary flow calculated by the following equation . Of course, a constant comparing the magnitude of the feedback correction factor may use a value other than 0.03 depending on the degree of the desired feedback control. If you want to set the degree of feedback control more strongly, you can use a smaller value. However, if the value is too small, voltage oscillation may occur due to excessive feedback. Conversely, if the degree of feedback control is set to be weak, a larger value can be used. However, if the value is too large, lack of feedback may result in lack of response.

In the above equation, C _current is the current pre-current flow, K is the feedback correction rate, and C _new is the new pre-flow calculated by the feedback control. That is, the result obtained by adding the integral part of the value obtained by multiplying the current full dictionary dictionary by the feedback correction ratio to the current total dictionary dictionary can be set as a new full dictionary dictionary.

The full dictionary control unit 154 obtains the feedback correction rate using the output voltage of the power supply unit 140 and the target voltage measured by the voltage measurement unit 152 during the transfer of the image and if the size of the feedback correction rate falls outside a certain range The output voltage of the power supply unit 140 can be kept within a certain range from the target voltage by adjusting the full-current flow. That is, it is possible to apply the target voltage in the constant voltage method through the feedback control of the full dictionary flow. As described above, since the power supply unit 140 includes only the constant-current-mode power supply unit and implements the constant-voltage method in terms of firmware, the power supply unit 140 is provided with the power supply unit of the constant voltage type, .

5 to 8 are flowcharts for explaining a transfer power control method according to another embodiment of the present invention. Hereinafter, a transfer power control method according to another embodiment of the present invention will be described in detail with reference to FIGS. 5 to 8. FIG.

Referring to FIG. 5, the transfer source power controller first determines an initial pre-current flow (S501). The detailed step of step S501 is shown in FIG. 6, the power source unit applies a constant current to the transfer unit in a constant current mode (S601). Then, the output voltage of the power source unit at this time is measured (S603). Using the measured output voltage, (S605). At this time, since the output voltage of the power supply unit is not constant within the interval, it can be measured several times and the average value thereof can be used. For example, the system load of the image forming apparatus can be calculated by measuring the output voltage 25 times at 4 ms intervals and using the average value. When the system load is calculated, an appropriate initial pre-adaptation is determined based on the system load (S607)

Returning to FIG. 5, if the initial pre-flow is determined in step S501, the flow advances to step S503. In step S503, the power source unit applies the pre-pre-charge current to the transfer unit in a predetermined period before the image is transferred to the transfer medium, and determines the output voltage of the power source unit to be measured as the target voltage. Then, the target voltage is applied to the transfer unit by the constant voltage method to transfer the image to the transfer medium. (S505) At this time, the method of applying the target voltage to the transfer unit by the constant voltage method is as follows. When the power source unit includes the constant- When the power supply unit includes only the constant current type power supply unit, the output voltage of the power supply unit can be maintained at the target voltage through the feedback control of the full dictionary current. An embodiment in which the target voltage is applied through the feedback control of the full dictionary flow will be described in detail in Fig. 7 below. Finally, if there is a next page after the end of image transfer of one page, steps S503 and S505 are repeatedly performed (S507)

7 is a detailed view of the step S505 when only the constant current type power supply unit is provided in the power supply unit and the output voltage of the power supply unit is maintained at the target voltage by controlling all the pre-currents of the power supply unit by firmware. 7, the power source unit applies an initial pre-current to the transfer unit to start image transfer (S701). During the transfer of the image, the output voltage of the power source unit is measured (S703). At this time, Since the voltage changes with time, it can be measured several times and its average value can be used. For example, you can measure the output voltage 10 times at 4ms intervals and use the average value. When the measured output voltage of the power source deviates from the target voltage by more than a predetermined range, the output voltage can be maintained at the target voltage by adjusting the full-length pre-current applied from the power source unit. (S705) to be. Referring to FIG. 8, in step S801, the feedback correction ratio is calculated according to Equation (1). It is determined in step S803 whether the magnitude of the feedback correction rate is out of a predetermined range. In this embodiment, it is determined whether the magnitude of the feedback correction rate is 0.03 or more. If the magnitude of the feedback correction rate is smaller than 0.03, the flow advances to step S807 to maintain the current full dictionary flow. However, if the magnitude of the feedback correction rate is equal to or greater than 0.03, the process proceeds to step S805 and a new full dictionary flow is set according to Equation (2). Of course, the constant for comparing the magnitude of the feedback correction factor may be set to a value other than 0.03 depending on the degree of the desired feedback control. If you want to set the degree of feedback control more strongly, you can use a smaller value. However, if the value is too small, voltage oscillation may occur due to excessive feedback. Conversely, if the degree of feedback control is set to be weak, a larger value can be used. However, if the value is too large, lack of feedback may result in lack of response.

When the step S705 is finished, it is determined whether the image transfer section is ended in the step S707. If the step S705 is finished, the step S507 of FIG. 5 is performed, and if not, the steps S703 and S705 are repeated.

The present invention has been described with reference to the preferred embodiments. It will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. Therefore, the disclosed embodiments should be considered in an illustrative rather than a restrictive sense. The scope of the present invention is indicated by the appended claims rather than by the foregoing description, and all differences within the scope of equivalents thereof should be construed as being included in the present invention.

110: developing units 111 to 114:
120: Transfer parts 121 to 124: Primary transfer roller
127: intermediate transfer belt 128: secondary transfer roller
130: fixing unit 131, 132: fixing roller
140: power supply unit 150: transfer power control unit
152: voltage measuring unit 154:

Claims (18)

A transfer unit that transfers an image formed on the photosensitive member to a transfer medium;
A power supply unit for supplying a transfer power to the transfer unit; And
And a transfer power source control unit for controlling transfer power supplied from the power source unit to the transfer unit,
The transfer power source control unit sets the output voltage of the power source unit, which is measured by applying an initial pre-discharge current to the transfer unit at a predetermined interval before the image is transferred to the transfer medium, as a target voltage, Calculating a feedback correction ratio using the output voltage of the power source unit and the set target voltage measured while the image is transferred to the transfer medium based on the calculated correction ratio, And controls the full-length pre-stream to be applied to the transfer section so as to maintain the voltage.
The method according to claim 1,
The transfer power control unit,
Wherein the image forming apparatus calculates the system load of the image forming apparatus using the output voltage of the power source unit measured when the power source unit applies a constant current to the transfer unit and determines the initial pre- .
The method according to claim 1,
The transfer power control unit,
A voltage measuring unit for measuring an output voltage of the power supply unit; And
And a full-length dictionary control unit for controlling the full-length dictionary current to be applied to the transfer unit by the power source unit according to an output voltage of the power source unit measured by the voltage measuring unit.
delete The method of claim 3,
Wherein the pre-
And sets the value obtained by adding the integral part of the value obtained by multiplying the current full dictionary flow and the feedback correction ratio to the present full dictionary flow as a new full dictionary flow if the magnitude of the feedback correction rate deviates from a certain range. .
6. The method of claim 5,
The full dictionary control unit divides the value obtained by subtracting the output voltage of the power source unit measured while the image is transferred from the target voltage by a sum of the target voltage and the output voltage of the power source unit measured while the image is transferred, And determines the result of the multiplication as a feedback correction rate.
The method according to claim 6,
Wherein the full dictionary control unit adjusts the degree of feedback control by adjusting the constant value.
The method according to claim 1,
The transfer power control unit
The output voltage of the power source unit is measured a predetermined number of times while the power source unit applies the initial pre-discharge current to the transfer unit in a predetermined period before the image is transferred to the transfer medium, Is set to a predetermined value.
The method according to claim 1,
Wherein the transfer power source control unit sets the target voltage in a section before an image is transferred to the transfer medium after the transfer medium is drawn into the transfer unit.
A transfer power control method for an image forming apparatus including a transfer section for transferring an image to a transfer medium and a power section for supplying transfer power to the transfer section,
Determining an initial pre-existing flow;
Setting an output voltage of the power source unit, which is measured when the power source unit applies the determined initial pre-discharge current to the transfer unit at a predetermined interval before the image is transferred to the transfer medium, to a target voltage; And
Calculating a feedback correction ratio using the output voltage of the power source unit and the set target voltage while the image is transferred to the transfer medium, And controlling an entire pre-stream to be applied to the transfer unit so that an output voltage of the power source unit maintains the target voltage, thereby transferring an image to the transfer medium.
11. The method of claim 10,
Wherein the step of determining the pre-
Wherein the image forming apparatus calculates the system load of the image forming apparatus using the output voltage of the power source unit measured when the power source unit applies a constant current to the transfer unit and determines the initial pre- A method of controlling the transfer power of the battery.
11. The method of claim 10,
The step of transferring the image comprises:
Measuring an output voltage of the power source while the image is transferred to the transfer medium by applying a full pre-current to the transfer portion from the power source portion; And
And controlling the total pre-current to be applied to the transfer unit in the power source unit so that the measured output voltage of the power source unit maintains the target voltage while the image is transferred. Way.
13. The method of claim 12,
The step of adjusting the pre-
And setting a value obtained by adding an integer part of a value obtained by multiplying a current full dictionary dictionary and the feedback correction rate to a total previous dictionary dictionary by a new full dictionary dictionary if the size of the feedback correction factor is out of a predetermined range. Of the image forming apparatus.
14. The method of claim 13,
Wherein the step of calculating the feedback correction factor comprises:
A value obtained by dividing a value obtained by subtracting the output voltage of the power source portion measured during the transfer of the image from the target voltage by a sum of the target voltage and an output voltage of the power source portion measured during the transfer of the image, And the correction factor is determined as the correction factor.
15. The method of claim 14,
And controlling the degree of feedback control by adjusting the constant value.
11. The method of claim 10,
The step of setting the target voltage includes:
The output voltage of the power source unit is measured a predetermined number of times while the power source unit applies the initial pre-discharge current to the transfer unit in a predetermined period before the image is transferred to the transfer medium, Of the image forming apparatus.
11. The method of claim 10,
The predetermined period may include:
Wherein the image forming apparatus is a section before an image is transferred to the transfer medium after the transfer medium is drawn into the transfer section.
A computer-readable recording medium storing a program for causing a computer to execute the method of any one of claims 10 to 17.

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