JP6036068B2 - Image forming apparatus and image forming system - Google Patents

Description

  The present invention relates to an image forming apparatus and an image forming system.

  In an electrophotographic image forming apparatus, an electrostatic latent image is formed on a uniformly charged image carrier, and the formed electrostatic latent image is developed with toner to form a toner image. The formed toner image Is transferred to a recording paper and fixed, thereby forming an image on the recording paper.

  By the way, recording paper usually has unevenness, and toner is not easily transferred to the concave portion compared to the convex portion. Therefore, when forming an image on recording paper having large unevenness, the toner is not transferred to the concave portion and the image is white. Density unevenness such as omission may occur.

  For this reason, for example, in Patent Document 1, depending on the size of the unevenness of the transfer object, a DC voltage is applied to the transfer unit to transfer the image to the transfer object, or a DC voltage and an AC voltage are applied. A technique is disclosed in which whether or not to transfer an image onto a transfer target by applying a superimposed superimposed voltage to a transfer unit is switched by a relay.

  However, in the above-described prior art, when the transfer portion is applied with the superimposed voltage, it may take more time for the DC voltage to rise than when the transfer portion is applied with the DC voltage. There is a risk of density unevenness and density dilution.

  The present invention has been made in view of the above circumstances, and an object thereof is to provide an image forming apparatus and an image forming system capable of preventing density unevenness and density dilution from occurring in an image. To do.

In order to solve the above-described problems and achieve the object, an image forming apparatus according to an aspect of the present invention includes a transfer unit that transfers a toner image to a transfer target, and a superimposed voltage obtained by superimposing an AC voltage and a DC voltage. Superimposing power supply means for outputting, switching means for switching whether or not to apply the outputted superimposing voltage to the transfer means, and when applying the transferring means with the superimposing voltage, the superimposing power supply means from the superimposing voltage Power supply control means for switching the switching means so that the superimposed voltage is applied to the transfer means in a state where the superimposed voltage is output, and the power supply control means applies the DC voltage to the superimposed power supply means at a first timing. And the superimposing power source means outputs the AC voltage at a second timing, and the switching means at a third timing that is later than the first timing and the second timing. Switches.

An image forming system according to another aspect of the present invention is an image forming system having an image forming apparatus, and the image forming apparatus includes a transfer unit that transfers a toner image to a transfer target, an alternating voltage, and a direct current. Superimposing power supply means for outputting a superposed voltage superposed on the voltage, and switching means for switching whether to apply the outputted superposed voltage to the transfer means, and the image forming system uses the superposed voltage. In the case of applying the transfer means, the power supply control means includes a power supply control means for switching the switching means so that the superimposed voltage is applied to the transfer means in a state where the superimposed voltage is output from the superimposed power supply means. Causes the superimposed power supply means to output the DC voltage at a first timing, causes the superimposed power supply means to output the AC voltage at a second timing, and And switching said switching means at third timing later than the second timing.

  According to the present invention, it is possible to prevent the occurrence of density unevenness or density dilution in an image.

FIG. 1 is a mechanical configuration diagram illustrating an example of a printing apparatus according to the first embodiment. FIG. 2 is a mechanical configuration diagram illustrating an example of an image forming unit according to the first embodiment. FIG. 3 is an explanatory diagram illustrating an example of the principle of toner adhesion to a recording sheet when a superimposed bias is applied to the secondary transfer unit facing roller by the secondary transfer power supply according to the first embodiment. FIG. 4 is a block diagram illustrating an example of an electrical configuration of the printing apparatus according to the first embodiment. FIG. 5 is a block diagram illustrating an example of an electrical configuration of the secondary transfer power supply according to the first embodiment. FIG. 6 is an explanatory diagram of an example of the rising timing of the high voltage output by the superimposed bias and the high voltage output by the DC bias. FIG. 7 is a timing chart of an example when high voltage output is performed with a superimposed bias. FIG. 8 is a flowchart illustrating an example of a transfer control process performed by the printing apparatus according to the first embodiment. FIG. 9 is a block diagram illustrating an example of an electrical configuration of the printing apparatus according to the second embodiment. FIG. 10 is a timing chart of an example when high voltage output is performed with a superimposed bias. FIG. 11 is a flowchart illustrating an example of a transfer control process performed by the printing apparatus according to the second embodiment. FIG. 12 is a block diagram illustrating an example of an electrical configuration of the printing apparatus according to the third embodiment. FIG. 13 is a block diagram illustrating an example of the electrical configuration of the secondary transfer power supply according to the third embodiment. FIG. 14 is a timing chart of an example when high voltage output is performed with a superimposed bias. FIG. 15 is a block diagram illustrating an example of an electrical configuration of the printing apparatus 601 according to the fourth embodiment. FIG. 16 is a block diagram illustrating an example of an electrical configuration of the secondary transfer power supply 700 according to the fourth embodiment. FIG. 17 is a block diagram illustrating an example of an electrical configuration of a printing apparatus 801 according to the fifth embodiment. FIG. 18 is a block diagram illustrating an example of an electrical configuration of a printing apparatus 901 according to the sixth embodiment. FIG. 19 is a block diagram illustrating an example of an electrical configuration of the secondary transfer power supply 1000 according to the sixth embodiment. FIG. 20 is an explanatory diagram of the fifth modification. FIG. 21 is an explanatory diagram of the sixth modification. FIG. 22 is an explanatory diagram of Modification 7. FIG. 23 is an explanatory diagram of Modification 8. FIG. 24 is an explanatory diagram of Modification 9. FIG. 25 is an external view illustrating an example of a printing system according to the tenth modification. FIG. 26 is a hardware configuration diagram illustrating an example of a server device according to the tenth modification.

  Hereinafter, embodiments of an image forming apparatus and an image forming system according to the present invention will be described in detail with reference to the accompanying drawings. In the following embodiments, the image forming apparatus of the present invention is an electrophotographic color printing apparatus, specifically, four colors of yellow (Y), magenta (M), cyan (C), and black (K). However, the present invention is not limited to this example. However, the present invention is not limited to this example. The image forming apparatus of the present invention can be applied to both color and monochrome as long as it is an apparatus that forms an image by an electrophotographic method. For example, the image forming apparatus can be applied to an electrophotographic copying machine or a multifunction peripheral (MFP). Applicable. Note that a multifunction peripheral is a device having at least two functions among a printing function, a copying function, a scanner function, and a facsimile function.

(First embodiment)
First, the configuration of the printing apparatus according to the first embodiment will be described.

  FIG. 1 is a mechanical configuration diagram illustrating an example of a printing apparatus 1 according to the first embodiment. As shown in FIG. 1, the printing apparatus 1 includes an image forming unit 10Y, 10M, 10C, and 10K, an intermediate transfer belt 60, support rollers 61 and 62, a secondary transfer unit counter roller (repulsive roller) 63, and the like. A secondary transfer roller 64, a paper cassette 70, a paper feed roller 71, a transport roller pair 72, a fixing device 90, and a secondary transfer power source 200.

  As shown in FIG. 1, the image forming units 10Y, 10M, 10C, and 10K are arranged in the order of the image forming units 10Y, 10M, 10C, and 10K from the upstream side in the moving direction (arrow a direction) of the intermediate transfer belt 60. Arranged along the intermediate transfer belt 60.

  FIG. 2 is a mechanical configuration diagram illustrating an example of the image forming unit 10Y according to the first embodiment. As shown in FIG. 2, the image forming unit 10Y includes a photosensitive drum 11Y, a charging device 20Y, a developing device 30Y, a primary transfer roller 40Y, and a cleaning device 50Y. The image forming unit 10Y and the irradiation device (not shown) perform yellowing on the photosensitive drum 11Y by performing an image forming process (charging process, irradiation process, developing process, transfer process, and cleaning process) on the photosensitive drum 11Y. The toner image (color component image) is formed and transferred to the intermediate transfer belt 60.

  The image forming units 10M, 10C, and 10K all have the same components as the image forming unit 10Y. The image forming unit 10M forms a magenta toner image by performing an image forming process. The image forming unit 10C forms a cyan toner image by performing an image forming process, and the image forming unit 10K forms a black toner image by performing an image forming process. Therefore, in the following, description will be mainly given of the constituent elements of the image forming unit 10Y, and the constituent elements of the image forming units 10M, 10C, and 10K are denoted by Y added to the reference numerals of the constituent elements of the image forming unit 10Y. Instead, M, C, and K are added (see FIG. 1), and description thereof is omitted.

  The photoreceptor drum 11Y is an image carrier and is rotationally driven in the direction of arrow b by a photoreceptor drum driving device (not shown). The photoreceptor drum 11Y is an organic photoreceptor having an outer diameter of 60 mm, for example. Similarly, the photosensitive drums 11M, 11C, and 11K are rotationally driven in the direction of arrow b by a photosensitive drum driving device (not shown).

  The black photosensitive drum 11K and the color photosensitive drums 11Y, 11M, and 11C may be driven to rotate independently. Thus, when forming a monochrome image, only the black photosensitive drum 11K is rotationally driven, and when forming a color image, the photosensitive drums 11Y, 11M, 11C, and 11K are simultaneously rotationally driven. it can.

  First, in the charging step, the charging device 20Y charges the surface of the photosensitive drum 11Y that is being rotationally driven. Specifically, the charging device 20Y applies a voltage obtained by superimposing an AC voltage on a DC voltage to a charging roller (not shown) that is, for example, a roller-shaped conductive elastic body. As a result, the charging device 20Y directly discharges between the charging roller and the photosensitive drum 11Y, and charges the photosensitive drum 11Y to a predetermined polarity, for example, a negative polarity.

  Subsequently, in the irradiation step, an irradiation device (not shown) irradiates the charged surface of the photosensitive drum 11Y with the laser light L that has been light-modulated, thereby forming an electrostatic latent image on the surface of the photosensitive drum 11Y. As a result, the portion where the absolute value of the potential of the surface portion of the photosensitive drum 11Y is lowered by the irradiation with the laser beam L becomes an electrostatic latent image (image portion), and the absolute value of the potential is kept high without being irradiated with the laser beam L. The sagging part becomes the background part.

  Subsequently, in the developing process, the developing device 30Y develops the electrostatic latent image formed on the photoreceptor drum 11Y with yellow toner, and forms a yellow toner image on the photoreceptor drum 11Y.

  The developing device 30Y includes a storage container 31Y, a developing sleeve 32Y stored in the storage container 31Y, and a screw member 33Y stored in the storage container 31Y. The storage container 31Y stores a two-component developer having yellow toner and a carrier. The developing sleeve 32Y is a developer carrier, and is disposed so as to face the photosensitive drum 11Y through the opening of the storage container 31Y. The screw member 33Y is a stirring member that conveys the developer while stirring. The screw member 33Y is disposed on the developer supply side on the developing sleeve side and on the receiving side that receives supply from a toner supply device (not shown), and is rotatably supported by the storage container 31Y by a bearing member (not shown). Yes.

  Subsequently, in the transfer process, the primary transfer roller 40Y transfers the yellow toner image formed on the photosensitive drum 11Y to the intermediate transfer belt 60. Note that a small amount of untransferred toner remains on the photosensitive drum 11Y even after the toner image is transferred.

  The primary transfer roller 40Y is an elastic roller having a conductive sponge layer, for example, and is disposed so as to be pressed against the photosensitive drum 11Y from the back surface of the intermediate transfer belt 60. The elastic roller is applied with a constant current controlled bias as a primary transfer bias. For example, the primary transfer roller 40Y has an outer shape of 16 mm, a mandrel diameter of 10 mm, and a sponge layer resistance R of about 3E7Ω. The resistance R of the sponge layer is determined from the current I flowing when a voltage V of 1000 V is applied to the mandrel of the primary transfer roller 40Y with a grounded metal roller having an outer diameter of 30 mm pressed by 10 N, from the current I. It is a value calculated using the law (R = V / I).

  Subsequently, in the cleaning process, the cleaning device 50Y wipes off the untransferred toner remaining on the photosensitive drum 11Y. The cleaning device 50Y includes a cleaning blade 51Y and a cleaning brush 52Y. The cleaning blade 51Y cleans the surface of the photoconductive drum 11Y while being in contact with the photoconductive drum 11Y from the counter direction with respect to the rotation direction of the photoconductive drum 11Y. The cleaning brush 52Y cleans the surface of the photosensitive drum 11Y while being in contact with the photosensitive drum 11Y while rotating in the direction opposite to the rotation direction of the photosensitive drum 11Y.

  Returning to FIG. 1, the intermediate transfer belt 60 is an endless belt wound around a plurality of rollers such as support rollers 61 and 62 and a secondary transfer unit facing roller 63, and one of the support rollers 61 and 62 is rotationally driven. As a result, it moves endlessly in the direction of arrow a. First, a yellow toner image is transferred to the intermediate transfer belt 60 by the image forming unit 10Y. Subsequently, the magenta toner image is transferred by the image forming unit 10M, the cyan toner image is transferred by the image forming unit 10C, and the image forming unit 10K is pressed. Black toner images are sequentially superimposed and transferred. As a result, a full-color toner image (full-color image) is formed on the intermediate transfer belt 60. The intermediate transfer belt 60 conveys the formed full-color toner image between the secondary transfer portion facing roller 63 and the secondary transfer roller 64. For example, the intermediate transfer belt 60 has a thickness of 20 to 200 μm (preferably about 60 μm) and a volume resistivity of 6.0 to 13.0 Log Ωcm (preferably 7.5 to 12.5 Log Ωcm, more preferably about 9 Log Ωcm) and an endless carbon-dispersed polyimide resin having a surface resistivity of 9.0 to 13.0 Log Ωcm (preferably 10.0 to 12.0 Log Ωcm). The volume resistivity is a resistance measurement value at 100 V, 10 sec, manufactured by Mitsubishi Chemical Hiresta HRS probe, and the surface resistivity is a resistance measurement value at 500 V, 10 sec, manufactured by Mitsubishi Chemical Hiresta HRS probe. The support roller 62 is grounded.

  In the paper cassette 70, a plurality of recording papers are accommodated on each tray (not shown). It is assumed that the recording paper has a different paper type and size for each tray. In the first embodiment, the recording paper (an example of the transfer target) is, for example, plain paper or a highly concavo-convex resack paper, but is not limited thereto.

  The paper feed roller 71 is in contact with the recording paper P positioned at the top of the tray of the paper cassette 70 and feeds the recording paper P in contact therewith.

  The transport roller pair 72 transports the recording paper P fed by the paper feed roller 71 between the secondary transfer portion facing roller 63 and the secondary transfer roller 64 (in the direction of arrow c) at a predetermined timing.

  The secondary transfer portion facing roller 63 and the secondary transfer roller 64 are conveyed by the intermediate transfer belt 60 at a secondary transfer nip (not shown) between the secondary transfer portion facing roller 63 and the secondary transfer roller 64. The full-color toner image is collectively transferred onto the recording paper P transported by the transport roller pair 72.

  The secondary transfer portion facing roller 63 (an example of a transfer unit) is, for example, a conductive NBR rubber layer having an outer shape of 24 mm and a mandrel diameter of 16 mm. In addition, the value of resistance R of the conductive NBR rubber layer is 6.0 to 12.0 LogΩ (or SUS), and preferably 4.0 LogΩ. The secondary transfer roller 64 is, for example, a conductive NBR rubber layer having an outer shape of 24 mm and a mandrel diameter of 14 mm. In addition, the value of resistance R of the conductive NBR rubber layer is 6.0 to 8.0 LogΩ, and preferably 7.0 to 8.0 LogΩ. The volume resistance of the secondary transfer roller 64 is a resistance measurement value measured by rotation measurement. Weight: 5 N / one side, bias application: 1 KV applied to the transfer roller shaft, resistance of one roller rotation measured during 1 min measurement, average The value is a volume resistance.

  A secondary transfer power supply 200 for transfer bias is connected to the secondary transfer portion facing roller 63. The secondary transfer power supply 200 applies a voltage to the secondary transfer unit facing roller 63 and transfers the secondary transfer from the secondary transfer unit facing roller 63 in order to transfer the full-color toner image to the recording paper P at the secondary transfer nip. A current is supplied to GND through the roller 64. Specifically, the secondary transfer power source 200 applies only a DC voltage (hereinafter referred to as “DC bias”) to the secondary transfer unit facing roller 63 according to a user setting, or a DC voltage and an AC voltage. Or a superimposed voltage (hereinafter referred to as “superimposed bias”) is applied to the secondary transfer unit facing roller 63. As a result, a potential difference is generated between the secondary transfer portion facing roller 63 and the secondary transfer roller 64, and a voltage is generated in which the toner travels from the intermediate transfer belt 60 to the recording paper P side. Can be transferred to. Here, the potential difference in the first embodiment is (potential of the secondary transfer unit facing roller 63) − (potential of the secondary transfer roller 64).

  FIG. 3 is an explanatory diagram of an example of the principle of toner adhesion to the recording paper P when the superimposing bias is applied to the secondary transfer unit facing roller 63 by the secondary transfer power source 200 of the present embodiment. When the superimposed bias is applied to the secondary transfer unit facing roller 63, an AC waveform is obtained. Therefore, a voltage from the secondary transfer unit facing roller 63 to the secondary transfer roller 64 and the secondary transfer roller 64 to the secondary transfer unit facing roller are obtained. The voltage toward 63 is switched at a predetermined cycle. As a result, as shown in FIG. 3, when the toner T of the full-color toner image formed on the intermediate transfer belt 60 (not shown) starts to move toward the recording paper P and in the opposite direction, and reaches a certain voltage level. Toner adheres to the recesses of the recording paper P.

  Returning to FIG. 1, the fixing device 90 fixes the full-color toner image on the recording paper P by heating and pressurizing the recording paper P on which the full-color toner image is transferred. Then, the recording paper P on which the full-color toner image is fixed is discharged outside the printing apparatus 1.

  FIG. 4 is a block diagram illustrating an example of an electrical configuration of the printing apparatus 1 according to the first embodiment. As shown in FIG. 4, the printing apparatus 1 includes an engine control unit 100, a secondary transfer power source 200, and a secondary transfer unit facing roller 63.

  The engine control unit 100 performs engine control, for example, control related to image formation. The I / O control unit 110, a RAM (Random Access Memory) 120, a ROM (Read Only Memory) 130, and a CPU ( Central Processing Unit) 140.

  The I / O control unit 110 controls input / output of various signals, and controls input / output of signals exchanged with the secondary transfer power supply 200.

  Here, the secondary transfer power supply 200 will be described.

  FIG. 5 is a block diagram illustrating an example of an electrical configuration of the secondary transfer power supply 200 according to the first embodiment. As shown in FIG. 5, the secondary transfer power source 200 includes a superimposed power source 210, an AC relay 225, and a DC power source 230. In the first embodiment, the superimposed power source 210 is detachable from the secondary transfer power source 200, but is not limited thereto.

  The superimposed power supply 210 includes a D / A converter 211, a driver 212, a booster 213, a D / A converter 214, a driver 215, a booster 216, and an output unit 217.

  The D / A converter 211 receives from the I / O controller 110 a PWM_T2 (DC) signal (DC bias output signal) that sets the current or voltage of the DC high-voltage output T2 (DC) of the booster 213. The converted PWM_T2 (DC) signal is converted from digital to analog.

  The driving unit 212 drives the boosting unit 213 in accordance with the PWM_T2 (DC) signal converted into analog by the D / A conversion unit 211. The driving unit 212 outputs the output current value and the output voltage value of the DC high voltage output T2 (DC) of the boosting unit 213 to the I / O control unit 110. This is because the engine control unit 100 monitors the load state.

  The step-up unit 213 is driven by the drive unit 212, transforms the DC voltage from the superimposed power source 210, and performs a DC high-voltage output T2 (DC). The booster 213 outputs the output current value and the output voltage value of the DC high voltage output T2 (DC) to the drive unit 212. The DC high voltage output T2 (DC) is a high voltage output of −100 μA (−2 kV).

  The D / A converter 214 receives a PWM_T2 (AC) signal (AC bias output signal) that sets the current or voltage of the AC high voltage output T2 (AC) of the booster 216 from the I / O controller 110, and receives the input. The PWM_T2 (AC) signal is converted from digital to analog.

  The driving unit 215 drives the boosting unit 216 in accordance with the PWM_T2 (AC) signal converted into analog by the D / A conversion unit 214. The driving unit 215 outputs the output current value and output voltage value of the AC high voltage output T2 (AC) of the boosting unit 216 to the I / O control unit 110. This is because the engine control unit 100 monitors the load state.

  The step-up unit 216 is driven by the drive unit 215, transforms the AC voltage from the superimposed power supply 210, and superimposes the AC high-voltage output T2 (AC) and the DC high-voltage output T2 (DC) from the step-up unit 213 to superimpose high-voltage output. I do. The booster 216 outputs the output current value and the output voltage value of the AC high voltage output T2 (AC) to the drive unit 215. The AC high voltage output T2 (AC) is a high voltage output of 10 kVpp (1 mA). That is, the superimposed high voltage output of the superimposed power supply 210 is a high voltage output of −100 μA (−2 kV) +10 kVpp (1 mA).

  The output unit 217 performs the superimposed high voltage output (high voltage output by the superimposed bias) of the boost unit 216 to the AC relay 225. The output unit 217 includes a load adjusting capacitor.

  The AC relay 225 is a relay that switches whether to perform a superimposed high voltage output (a high voltage output by a superimposed bias) to the secondary transfer unit facing roller 63, and is based on an ACRY signal input from the I / O control unit 110. Switch on / off. When the AC relay 225 is on, the AC relay 225 outputs a superimposed high voltage to the secondary transfer unit facing roller 63.

  As described above, in the secondary transfer power source 200 of the first embodiment, whether or not the superimposed high voltage output is performed on the secondary transfer unit facing roller 63 is switched by the relay.

  The DC power supply 230 includes a D / A conversion unit 231, a driving unit 232, a boosting unit 233, a D / A conversion unit 234, a driving unit 235, a boosting unit 236, and an output unit 237.

  The D / A converter 231 receives a PWM_T2 (−) signal (DC bias output signal) that sets the current or voltage of the DC high-voltage output T2 (−) of the booster 233 from the I / O control unit 110. The PWM_T2 (−) signal is converted from digital to analog.

  The driving unit 232 drives the boosting unit 233 in accordance with the PWM_T2 (−) signal converted into analog by the D / A conversion unit 231. In addition, the drive unit 232 outputs the output current value and output voltage value of the DC high voltage output T2 (−) of the booster 233 to the I / O controller 110. This is because the engine control unit 100 monitors the load state.

  The step-up unit 233 is driven by the drive unit 232, transforms the DC voltage from the DC power source 230, and performs a DC high-voltage output T2 (−). Further, the booster 233 outputs the output current value and output voltage value of the DC high voltage output T2 (−) to the drive unit 232. Note that the DC high voltage output T2 (−) is a high voltage output of −100 μA (−10 kV).

  The D / A converter 234 receives from the I / O controller 110 a PWM_T2 (+) signal (reverse bias output signal) that sets the current or voltage of the DC high-voltage output T2 (+) of the booster 236. The converted PWM_T2 (+) signal is converted from digital to analog.

  The driving unit 235 drives the boosting unit 236 in accordance with the PWM_T2 (+) signal converted into analog by the D / A conversion unit 234. In addition, the drive unit 235 outputs the output current value and output voltage value of the DC high-voltage output T2 (+) of the booster 236 to the I / O controller 110. This is because the engine control unit 100 monitors the load state.

  The step-up unit 236 is driven by the drive unit 235, transforms the DC voltage from the DC power source 230, and performs a DC high-voltage output T2 (+). The booster 236 outputs the output current value and output voltage value of the DC high voltage output T2 (+) to the drive unit 235. The DC high voltage output T2 (+) is a high voltage output of 2 kV (50 μA).

  The output unit 237 combines the DC high voltage output T2 (−) of the boosting unit 233 and the DC high voltage output T2 (+) of the boosting unit 236, and outputs the DC high voltage output (DC bias) to the secondary transfer unit facing roller 63. High pressure output).

  Here, the difference in the DC rising timing between the high voltage output by the superimposed bias and the high voltage output by only the DC bias will be described. Note that the term “rise” refers to a state in which there is a potential difference regardless of plus or minus from a state without potential difference (0 kV). Further, for reference, the falling means that a state having a potential difference regardless of plus or minus changes from a state having no potential difference (0 kV).

  FIG. 6 is an explanatory diagram of an example of the rising timing of the high voltage output by the superimposed bias and the high voltage output by the DC bias. As shown in FIG. 6, when the DC power source 230 outputs a high voltage only with a DC bias, the DC power source 230 is instructed to output a DC bias (output of a DC bias output signal to the DC power source 230) and then the DC power source. It takes 50 ms for the 230 bias value to reach the target value (−10 kV). On the other hand, when high voltage is output to the superimposed power source 210 with a superimposed bias, the bias of the superimposed power source 210 is output after the superimposed power source 210 is instructed to output a superimposed bias (DC) (output of a DC bias output signal to the superimposed power source 210). It takes 200 ms for the value to reach the target value (−10 kV). Also, after the superimposing power supply 210 is instructed to output the superimposing bias (AC) (output of the AC bias output signal to the superimposing power supply 210), the bias value of the superimposing power supply 210 reaches the target value (10 kVpp). 45 ms.

  As described above, when a high voltage is output to the superimposed power source 210 with a superimposed bias, since AC is superimposed on a DC having a large bias output value, the bias value of the superimposed bias (DC) is higher than when a high voltage is output only with a DC bias. It takes time to reach the target value (until the voltage rises). This is because the load adjustment capacitor provided in the output unit 217 of the secondary transfer power supply 200 has a certain amount of capacitance to maintain the AC waveform, but the superimposed bias (DC) boosting unit 213. This is because constant current control is performed and output is performed at a predetermined low current to prevent inrush, and it takes time to charge the superimposed bias (DC) by the load adjusting capacitor. As a result, the voltage rise time is delayed. The superimposed bias (AC) is also charged to the load adjustment capacitor, but the booster 216 of the superimposed bias (AC) is controlled at a constant voltage, and no problem occurs even if a large voltage is superimposed from the beginning. Therefore, it does not take much time to charge the capacitor for load adjustment.

  As described above, the time required for the bias value to reach the target value differs depending on the type of power supply and voltage, so the output timing of various bias output signals is controlled to set the target value at the target timing of the bias value. It is complicated.

  Therefore, in the first embodiment, when a high voltage is output to the superimposed power supply 210 with a superimposed bias, the bias value of the superimposed bias is set to a target value at a target timing by switching the AC relay 225. Therefore, according to the first embodiment, the bias value of the superimposed bias can be set to the target value at the target timing with simple control.

  Returning to FIG. 4, the RAM 120 is a volatile storage device (memory), and is used as a work area such as the CPU 140.

  The ROM 130 is a nonvolatile read-only storage device (memory), and stores various programs executed by the printing apparatus 1 and data used for various processes executed by the printing apparatus 1. For example, the ROM 130 outputs a first timing which is an output timing of a DC bias output signal to the secondary transfer power source 200 when the secondary transfer power source 200 outputs a high voltage with a superimposed bias, and an AC bias output signal to the secondary transfer power source 200. The second timing, which is the output timing, the third timing, which is the timing for switching the AC relay 225 from OFF to ON, and the output of the DC bias output signal and the AC bias output signal are stopped, and the AC relay 225 is switched from ON to OFF. Specific information for specifying the fourth timing to be switched to is stored. The third timing is a timing later than the first timing and the second timing, and the fourth timing is a timing later than the third timing.

  The specifying information specifies, for example, the first timing to the fourth timing based on a print start reference signal indicating a print start reference. Specifically, the specification information specifies the first timing to the fourth timing by the elapsed time after the CPU 140 receives the print start reference signal.

  Here, since it takes about 50 ms for the switching of the AC relay 225 to be completed, the third timing may be 50 ms before the target timing. For example, if the time from when the CPU 140 receives the print start reference signal to the target timing is 250 ms, the third timing may be the time when 200 ms has elapsed since the CPU 140 received the print start reference signal.

  The first timing may be a timing at which the bias value of the superimposed bias (DC) becomes the target value (−10 kV) by the target timing, and after the CPU 140 receives the print start reference signal, the first timing is higher than the target timing. Any timing may be used as long as it is before 200 ms. For example, if the time from when the CPU 140 receives the print start reference signal to the target timing is 250 ms, the first timing may be the time when 50 ms has elapsed since the CPU 140 received the print start reference signal.

  The second timing may also be a timing at which the bias value of the superimposed bias (AC) reaches the target value (10 kVpp) before the target timing, and after the CPU 140 receives the print start reference signal, 45 ms from the target timing. Any timing may be used as long as before. For example, if the time from when the CPU 140 receives the print start reference signal to the target timing is 250 ms, the second timing may be the time when 50 ms has elapsed since the CPU 140 received the print start reference signal.

  The fourth timing may be determined according to the transfer time. For example, when the time from the CPU 140 receiving the print start reference signal to the target timing is 250 ms and the transfer time is 450 ms, the fourth timing is 700 ms after the CPU 140 receives the print start reference signal. It may be at the point of time.

  The ROM 130 also stores specific information for specifying the output timing of various signals when the secondary transfer power supply 200 outputs a high voltage only with a DC bias, but the description thereof is omitted here.

  The CPU 140 accepts an input of a print start reference signal or accepts a user setting for a high voltage output from an operation unit (not shown) such as an operation panel. For example, the user inputs “high voltage output with superimposed bias” as the user setting of the high voltage output from the operation unit when the recording paper is a highly-roughened leather paper, and from the operation unit when the recording paper is plain paper. As a user setting for high voltage output, “high voltage output with only DC bias” is input. Then, the CPU 140 causes the secondary transfer power supply 200 to output a high voltage according to the user setting via the I / O control unit 110. The CPU 140 includes a power supply control unit 142.

  FIG. 7 is a timing chart of an example when high voltage output is performed with a superimposed bias. FIG. 8 is a flowchart illustrating an example of the transfer control process performed by the printing apparatus 1 according to the first embodiment, and illustrates the transfer control process when high voltage output is performed with a superimposed bias.

  When the user setting is “superimposed bias and high voltage output” and the CPU 140 accepts the input of the print start reference signal, the power controller 142 starts measuring elapsed time, turns on the reverse bias output signal, The reverse bias output signal is output from the / O control unit 110 to the secondary transfer power supply 200 (step S101). As a result, the DC power supply 230 starts high-voltage output with a reverse bias.

  Subsequently, the power control unit 142 refers to the elapsed time since the input of the print start reference signal and the specific information, and at the first and second timings that are 50 ms after the input of the print start reference signal to the CPU 140. Then, the superimposed bias (DC) output signal, which is a DC bias output signal for the superimposed bias, is turned on, and the superimposed bias (DC) output signal is output from the I / O control unit 110 to the secondary transfer power supply 200, and the superimposed bias is also generated. The superimposed bias (AC) output signal, which is an AC bias output signal, is turned on, and the superimposed bias (AC) output signal is output from the I / O control unit 110 to the secondary transfer power supply 200 (step S103). As a result, the superimposed power source 210 starts high voltage output with the superimposed bias, and when 200 ms elapses, the target bias value (−10 kV) is obtained. However, at this time, since the AC relay 225 is off, it is not applied to the secondary transfer portion facing roller 63.

  Subsequently, when the power supply control unit 142 is notified to the CPU 140 that the leading edge of the recording sheet has been detected, the power supply control unit 142 turns off the reverse bias output signal and outputs the reverse bias output from the I / O control unit 110 to the secondary transfer power supply 200. The signal output is stopped (step S105). Thereby, the DC power supply 230 ends the high voltage output with the reverse bias.

  Subsequently, the power supply control unit 142 refers to the elapsed time since the input of the print start reference signal and the specific information, and at the third timing which is 200 ms after the input of the print start reference signal to the CPU 140, the ACRY The signal is turned on, and the ACRY signal is output from the I / O control unit 110 to the secondary transfer power supply 200. When the ACRY signal is input from the I / O control unit 110, the secondary transfer power supply 200 switches the AC relay 225 from off to on (step S107), and the switching is completed after about 50 ms, and the secondary transfer unit A high voltage output with a superimposed bias is started with respect to the opposing roller 63. As a result, the superimposing power source 210 transfers the full-color toner image onto the recording paper P until 250 ms elapses after the print start reference signal is input to the CPU 140, that is, the secondary transfer unit facing roller 63 and the secondary transfer roller 64. Until then, the target bias value (−10 kV) can be applied to the secondary transfer portion facing roller 63.

  Subsequently, the power supply control unit 142 refers to the elapsed time since the input of the print start reference signal and the specific information, and when the fourth timing is 700 ms after the input of the print start reference signal to the CPU 140, The bias (DC) output signal and the superimposed bias (AC) output signal are turned off, and the superimposed bias (DC) output signal and the superimposed bias (AC) output signal are output from the I / O control unit 110 to the secondary transfer power supply 200. Stop (step S109). As a result, the superimposed power source 210 ends the high voltage output with the superimposed bias. Further, at the fourth timing, the power supply control unit 142 turns off the ACRY signal and stops the output of the ACRY signal from the I / O control unit 110 to the secondary transfer power supply 200. As a result, the secondary transfer power source 200 switches the AC relay 225 from on to off (step S109). When about 50 ms elapses, the switching is completed, and the superimposed power source 210 uses the superimposed bias with respect to the secondary transfer unit facing roller 63. The high voltage output is terminated.

  In the first embodiment, the first timing and the second timing are set to the same timing, and the power supply control unit 142 outputs the superimposed bias (AC) output signal and the superimposed bias (DC) output signal at the same time. It is not limited. The order of output of the superimposed bias (AC) output signal and the superimposed bias (DC) output signal is not limited as long as the conditions of the first timing and the second timing described above are satisfied.

  Note that the description of the case where high voltage output is performed with only the DC bias is omitted.

  As described above, in the first embodiment, when high voltage is output to the superimposed power supply 210 with the superimposed bias, the bias value of the superimposed bias is set to the target value at the target timing by switching the AC relay 225. For this reason, according to the first embodiment, even when high voltage output is performed with a superimposed bias, a target bias value can be applied to the secondary transfer unit facing roller 63 before secondary transfer is performed. Unevenness and dilution of density can be reduced.

  Note that when high voltage output is performed with a superimposed bias, if the same control is performed as when high voltage output is performed with a DC bias, the bias value of the secondary transfer power supply 200 is the target bias value until the secondary transfer is performed. Since the target bias value cannot be applied to the secondary transfer portion facing roller 63, the image density unevenness and the density dilution occur.

  In particular, according to the first embodiment, by switching the AC relay 225, the bias value of the superimposed bias is set to the target value at the target timing, so that the secondary transfer can be performed with simple control. A target bias value can be applied to the secondary transfer portion facing roller 63.

(Second Embodiment)
In the second embodiment, an example in which the superimposed bias (DC) output signal and the superimposed bias (AC) output signal are output at timings different from those in the first embodiment will be described. In the following, differences from the first embodiment will be mainly described, and components having the same functions as those in the first embodiment will be given the same names and symbols as those in the first embodiment, and the description thereof will be made. Omitted.

  FIG. 9 is a block diagram illustrating an example of an electrical configuration of the printing apparatus 301 according to the second embodiment. As shown in FIG. 9, in the printing apparatus 301 of the second embodiment, the ROM 330 of the engine control unit 300 and the power control unit 342 of the CPU 340 are different from the printing apparatus 1 of the first embodiment.

  For example, the ROM 330 outputs a first timing which is an output timing of a DC bias output signal to the secondary transfer power supply 200 when the secondary transfer power supply 200 outputs a high voltage with a superimposed bias, and an AC bias output signal to the secondary transfer power supply 200. The second timing is the output timing, the third timing is the timing to switch the AC relay 225 from OFF to ON, the fourth timing is the timing to switch the AC relay 225 from ON to OFF, and the DC bias output signal and AC Specific information for specifying the fifth timing, which is the timing for stopping the output of the bias output signal, is stored. Note that the fifth timing is later than the fourth timing.

  The specifying information specifies, for example, the first timing to the fifth timing based on the start / end of the print job and the print start reference signal. Specifically, the specification information specifies the first and second timings by the elapsed time after the CPU 340 detects the start of the print job, and the CPU 340 receives the print start reference signal for the third and fourth timings. The fifth timing is specified by the elapsed time after the CPU 340 detects the end of the print job.

  The first and second timings may be, for example, the time when the CPU 340 detects the start of the print job, and the fifth timing may be, for example, the time when the CPU 340 detects the end of the print job. Note that the third and fourth timings may be the same as in the first embodiment.

  FIG. 10 is a timing chart of an example when high voltage output is performed with a superimposed bias. FIG. 11 is a flowchart illustrating an example of a transfer control process performed by the printing apparatus 301 according to the second embodiment, and illustrates the transfer control process when a high voltage output is performed with a superimposed bias.

  When the user setting is “superimposed bias and high voltage output”, the power controller 342 detects the start of the print job by the CPU 340 and turns on the superimposed bias (DC) output signal at the first and second timings. A superimposing bias (DC) output signal is output from the I / O control unit 110 to the secondary transfer power supply 200, and a superimposing bias (AC) output signal is turned on to superimpose from the I / O control unit 110 to the secondary transfer power supply 200. A bias (AC) output signal is output (step S201). As a result, the superimposed power source 210 starts high voltage output with the superimposed bias, and when 200 ms elapses, the target bias value (−10 kV) is obtained. However, at this time, since the AC relay 225 is off, it is not applied to the secondary transfer portion facing roller 63.

  Subsequently, when the CPU 340 accepts the input of the print start reference signal, the power supply control unit 342 starts measuring the elapsed time, turns on the reverse bias output signal, and transfers from the I / O control unit 110 to the secondary transfer power supply 200. A reverse bias output signal is output (step S203). As a result, the DC power supply 230 starts high-voltage output with a reverse bias.

  Subsequently, when the CPU 340 is notified that the leading edge of the recording paper has been detected, the power supply control unit 342 turns off the reverse bias output signal, and the secondary transfer power supply 200 (DC power supply 230) from the I / O control unit 110. The output of the reverse bias output signal to is stopped (step S205). Thereby, the DC power supply 230 ends the high voltage output with the reverse bias.

  Subsequently, the power supply control unit 342 refers to the elapsed time since the input of the print start reference signal and the specific information, and at the third timing which is 200 ms after the input of the print start reference signal to the CPU 340, the ACRY The signal is turned on, and the ACRY signal is output from the I / O control unit 110 to the secondary transfer power supply 200. When the ACRY signal is input from the I / O control unit 110, the secondary transfer power source 200 switches the AC relay 225 from off to on (step S207), and the switching is completed after about 50 ms, and the secondary transfer unit A high voltage output with a superimposed bias is started with respect to the opposing roller 63. As a result, the superimposed power supply 230 transfers the full-color toner image onto the recording paper P until 250 ms elapses after the print start reference signal is input to the CPU 340, that is, the secondary transfer unit facing roller 63 and the secondary transfer roller 64 transfer the full color toner image onto the recording paper P. Until then, the target bias value (−10 kV) can be applied to the secondary transfer portion facing roller 63.

  Subsequently, the power supply control unit 342 refers to the elapsed time since the input of the print start reference signal and the specific information, and when the fourth timing is 700 ms after the input of the print start reference signal to the CPU 340, the ACRY The signal is turned off, and output of the ACRY signal from the I / O control unit 110 to the secondary transfer power supply 200 is stopped. As a result, the secondary transfer power source 200 switches the AC relay 225 from on to off (step S209). When about 50 ms elapses, the switching is completed, and the superimposing power source 210 applies the superimposing bias to the secondary transfer unit facing roller 63. The application ends. However, the superimposed power supply 210 continues high-voltage output with a superimposed bias.

  Subsequently, when the end of the print job is detected by the CPU 340 and the fifth timing is reached, the power supply control unit 342 turns off the superimposed bias (DC) output signal and the superimposed bias (AC) output signal, and from the I / O control unit 110. The output of the superimposed bias (DC) output signal and the superimposed bias (AC) output signal to the secondary transfer power supply 200 is stopped (step S211). As a result, the superimposed power source 210 ends the high voltage output with the superimposed bias.

  As described above, the second embodiment also has the same effects as the first embodiment. In particular, in the second embodiment, since the output of the superimposed bias is continued during the execution of the print job, a target bias value can be applied to the secondary transfer portion facing roller 63 by the simpler control until the secondary transfer is performed. .

(Third embodiment)
In the third embodiment, an example will be described in which a DC power source that performs a high voltage output with a DC bias or a high voltage output with a reverse bias is also switched with a relay. In the following, differences from the first embodiment will be mainly described, and components having the same functions as those in the first embodiment will be given the same names and symbols as those in the first embodiment, and the description thereof will be made. Omitted.

  FIG. 12 is a block diagram illustrating an example of an electrical configuration of the printing apparatus 401 according to the third embodiment. As shown in FIG. 12, in the printing apparatus 401 of the third embodiment, the secondary transfer power supply 500 and the power supply control unit 442 of the CPU 440 of the engine control unit 400 are different from the printing apparatus 1 of the first embodiment.

  FIG. 13 is a block diagram illustrating an example of an electrical configuration of the secondary transfer power supply 500 according to the third embodiment. As shown in FIG. 13, the secondary transfer power supply 500 of the third embodiment is different from the first embodiment in that it further includes a DC relay 545.

  The DC relay 545 is a relay that switches whether or not to output DC high voltage to the secondary transfer unit facing roller 63, and is switched on / off by a DCRY signal input from the I / O control unit 110. When the DC relay 545 is on, the DC high voltage output from the output unit 237 is performed to the secondary transfer unit facing roller 63.

  As described above, in the secondary transfer power supply 500 of the third embodiment, whether to perform DC high-voltage output to the secondary transfer unit facing roller 63 is switched by a relay.

  FIG. 14 is a timing chart of an example when high voltage output is performed with a superimposed bias.

  When the user setting is “superimposed bias and high voltage output” and the CPU 440 accepts the input of the print start reference signal, the power controller 442 starts measuring the elapsed time, turns on the reverse bias output signal, The reverse bias output signal is output from the / O control unit 110 to the secondary transfer power supply 500, and then the DCRY signal is turned on, and the DCRY signal is output from the I / O control unit 110 to the secondary transfer power supply 500. When the DCRY signal is input from the I / O control unit 110, the secondary transfer power supply 500 switches the DC relay 545 from off to on, and the switching is completed after about 50 ms. As a result, the DC power supply 230 starts high-voltage output with a reverse bias.

  Subsequently, the power supply control unit 442 refers to the elapsed time since the input of the print start reference signal and the specific information, and at the first and second timings that are 50 ms after the input of the print start reference signal to the CPU 440. Then, the superimposed bias (DC) output signal, which is a DC bias output signal for the superimposed bias, is turned on, and the superimposed bias (DC) output signal is output from the I / O control unit 110 to the secondary transfer power supply 500, and the superimposed bias is also generated. The superimposed bias (AC) output signal, which is an AC bias output signal, is turned on, and the superimposed bias (AC) output signal is output from the I / O control unit 110 to the secondary transfer power supply 500. As a result, the superimposed power source 210 starts high voltage output with the superimposed bias, and when 200 ms elapses, the target bias value (−10 kV) is obtained. However, at this time, since the AC relay 225 is off, it is not applied to the secondary transfer portion facing roller 63.

  Subsequently, when the CPU 440 is notified that the leading edge of the recording sheet has been detected, the power supply control unit 442 turns off the reverse bias output signal and outputs the reverse bias output from the I / O control unit 110 to the secondary transfer power supply 500. The output of the signal is stopped, and then the DCRY signal is turned off, and the output of the DCRY signal from the I / O control unit 110 to the secondary transfer power supply 500 is stopped. Thereby, the secondary transfer power source 500 switches the DC relay 545 from on to off, and the switching is completed after about 50 ms, and the DC power source 230 ends the high-voltage output with the reverse bias.

  Subsequently, the power supply control unit 442 refers to the elapsed time since the input of the print start reference signal and the specific information, and at the third timing which is 200 ms after the input of the print start reference signal to the CPU 440, the ACRY The signal is turned on, and the ACRY signal is output from the I / O control unit 110 to the secondary transfer power source 500. When the ACRY signal is input from the I / O control unit 110, the secondary transfer power supply 500 switches the AC relay 225 from off to on, and the switching is completed after about 50 ms. On the other hand, the high voltage output with the superimposed bias is started. As a result, the superimposing power source 210 transfers the full-color toner image onto the recording paper P until 250 ms elapses after the print start reference signal is input to the CPU 440, that is, the secondary transfer unit facing roller 63 and the secondary transfer roller 64 Until then, the target bias value (−10 kV) can be applied to the secondary transfer portion facing roller 63.

  Subsequently, the power supply control unit 442 refers to the elapsed time since the input of the print start reference signal and the specific information, and at the fourth timing which is 700 ms after the input of the print start reference signal to the CPU 440, the superimposition is performed. The bias (DC) output signal and the superimposed bias (AC) output signal are turned off, and the superimposed bias (DC) output signal and the superimposed bias (AC) output signal are output from the I / O control unit 110 to the secondary transfer power supply 500. Stop. As a result, the superimposed power source 210 ends the high voltage output with the superimposed bias. Further, at the fourth timing, the power supply control unit 442 turns off the ACRY signal and stops the output of the ACRY signal from the I / O control unit 110 to the secondary transfer power supply 500. As a result, the secondary transfer power source 500 switches the AC relay 225 from on to off, and the switching is completed after about 50 ms, and the superimposing power source 210 outputs a high voltage output with a superimposing bias to the secondary transfer unit facing roller 63. finish.

  As described above, the third embodiment also has the same effect as the first embodiment.

(Fourth embodiment)
In the fourth embodiment, an example will be described in which a DC power source is a power source dedicated to high-voltage output with a reverse bias. In the following, differences from the first embodiment will be mainly described, and components having the same functions as those in the first embodiment will be given the same names and symbols as those in the first embodiment, and the description thereof will be made. Omitted.

  FIG. 15 is a block diagram illustrating an example of an electrical configuration of the printing apparatus 601 according to the fourth embodiment. As shown in FIG. 15, in the printing apparatus 601 of the fourth embodiment, the secondary transfer power source 700 is different from the printing apparatus 1 of the first embodiment.

  FIG. 16 is a block diagram illustrating an example of an electrical configuration of the secondary transfer power supply 700 according to the fourth embodiment. As shown in FIG. 16, the secondary transfer power supply 700 includes a superimposed power supply 710, an AC relay 225, and a DC power supply 730 dedicated to DC reverse bias.

  The superimposed power source 710 includes a D / A converter 711, a driver 712, a booster 713, a D / A converter 214, a driver 215, a booster 216, and an output unit 217.

  The D / A converter 711 receives from the I / O controller 110 a PWM_T2 (−) signal (DC bias output signal) that sets the current or voltage of the DC high voltage output T2 (−) of the booster 713. The PWM_T2 (−) signal is converted from digital to analog.

  The driving unit 712 drives the boosting unit 713 in accordance with the PWM_T2 (−) signal converted into analog by the D / A conversion unit 711. In addition, the drive unit 712 outputs the output current value and output voltage value of the DC high voltage output T2 (−) of the booster 713 to the I / O controller 110. This is because the engine control unit 100 monitors the load state.

  The step-up unit 713 is driven by the drive unit 712, transforms the DC voltage from the superimposed power source 710, and performs a DC high-voltage output T2 (−). The booster 713 outputs the output current value and output voltage value of the DC high voltage output T2 (−) to the drive unit 712. Note that the DC high voltage output T2 (−) is a high voltage output of −100 μA (−10 kV).

  The D / A converter 214 receives a PWM_T2 (AC) signal (AC bias output signal) that sets the current or voltage of the AC high voltage output T2 (AC) of the booster 216 from the I / O controller 110, and receives the input. The PWM_T2 (AC) signal is converted from digital to analog.

  The driving unit 215 drives the boosting unit 216 in accordance with the PWM_T2 (AC) signal converted into analog by the D / A conversion unit 214. The driving unit 215 outputs the output current value and output voltage value of the AC high voltage output T2 (AC) of the boosting unit 216 to the I / O control unit 110. This is because the engine control unit 100 monitors the load state.

  The boosting unit 216 is driven by the driving unit 215, transforms the AC voltage from the superimposed power source 710, and superimposes the AC high voltage output T2 (AC) and the DC high voltage output T2 (-) from the boosting unit 713 to superimpose high voltage output. I do. The booster 216 outputs the output current value and the output voltage value of the AC high voltage output T2 (AC) to the drive unit 215. The AC high voltage output T2 (AC) is a high voltage output of 10 kVpp (1 mA). That is, the superimposed high voltage output of the superimposed power supply 710 is a high voltage output of −100 μA (−10 kV) +10 kVpp (1 mA).

  However, when the PWM_T2 (AC) signal is not input to the D / A converter 214 and the AC high voltage output T2 (AC) is not performed, the voltage booster 216 receives the DC high voltage output T2 ( -) Is output as is.

  The output unit 217 outputs the superimposed high-voltage output or DC high-voltage output T2 (−) from the booster 216 to the AC relay 225. The output unit 217 includes a load adjusting capacitor.

  The AC relay 225 is a relay that switches whether to perform the superimposed high-voltage output or the DC high-voltage output T <b> 2 (−) with respect to the secondary transfer unit facing roller 63, and the ACRY signal input from the I / O control unit 110. Is switched on / off. When the AC relay 225 is on, the superimposed high-voltage output or the DC high-voltage output T <b> 2 (−) is applied to the secondary transfer unit facing roller 63.

  The DC power source 730 includes a D / A conversion unit 234, a driving unit 235, a boosting unit 236, and an output unit 237.

  The D / A converter 234 receives from the I / O controller 110 a PWM_T2 (+) signal (reverse bias output signal) that sets the current or voltage of the DC high-voltage output T2 (+) of the booster 236. The converted PWM_T2 (+) signal is converted from digital to analog.

  The driving unit 235 drives the boosting unit 236 in accordance with the PWM_T2 (+) signal converted into analog by the D / A conversion unit 234. In addition, the drive unit 235 outputs the output current value and output voltage value of the DC high-voltage output T2 (+) of the booster 236 to the I / O controller 110. This is because the engine control unit 100 monitors the load state.

  The step-up unit 236 is driven by the drive unit 235, transforms the DC voltage from the DC power source 730, and performs a DC high-voltage output T2 (+). The booster 236 outputs the output current value and output voltage value of the DC high voltage output T2 (+) to the drive unit 235.

  The output unit 237 performs the DC high voltage output T <b> 2 (+) of the booster 236 to the secondary transfer unit facing roller 63.

  Note that the transfer control processing when high voltage output is performed with the superimposed bias is the same as in the first embodiment. That is, FIG. 7 is a timing chart when high voltage output is performed with the superimposed bias, and FIG. 8 is a flowchart showing the transfer control process.

  As described above, the fourth embodiment also has the same effect as the first embodiment.

(Fifth embodiment)
In the fifth embodiment, an example in which a superimposed bias (DC) output signal and a superimposed bias (AC) output signal are output at timings different from those in the fourth embodiment will be described. Specifically, in the fifth embodiment, an example in which the superimposed bias (DC) output signal and the superimposed bias (AC) output signal are output at the timing described in the second embodiment in the power supply configuration of the fourth embodiment will be described. To do. In the following, differences from the fourth embodiment will be mainly described, and components having the same functions as those in the fourth embodiment will be given the same names and symbols as those in the fourth embodiment, and the description thereof will be made. Omitted. However, components having the same functions as those of the second embodiment are given the same names and symbols as those of the second embodiment even if they are different from the fourth embodiment, and the description thereof is omitted.

  FIG. 17 is a block diagram illustrating an example of an electrical configuration of a printing apparatus 801 according to the fifth embodiment. As shown in FIG. 17, the engine control unit 300 of the printing apparatus 801 of the fifth embodiment is the same as that of the second embodiment. That is, the ROM 330 stores specific information for specifying the first timing to the fifth timing. The power supply control unit 342 outputs a superimposed bias (DC) output signal from the I / O control unit 110 to the secondary transfer power supply 200 and the secondary transfer from the I / O control unit 110 at the first and second timings. A superimposed bias (AC) output signal is output to the power supply 200. At the third timing, the power supply control unit 342 outputs an ACRY signal from the I / O control unit 110 to the secondary transfer power supply 200 and switches the AC relay 225 from off to on. At the fourth timing, the power control unit 342 stops outputting the ACRY signal from the I / O control unit 110 to the secondary transfer power source 200 and switches the AC relay 225 from on to off. The power supply control unit 342 stops outputting the superimposed bias (DC) output signal and the superimposed bias (AC) output signal from the I / O control unit 110 to the secondary transfer power supply 200 at the fifth timing.

  Note that the transfer control process when high voltage output is performed with the superimposed bias is the same as in the second embodiment. That is, FIG. 10 is a timing chart when high voltage output is performed with the superimposed bias, and FIG. 11 is a flowchart showing the transfer control process.

  As described above, the fifth embodiment has the same effects as those of the second embodiment.

(Sixth embodiment)
In the sixth embodiment, an example in which a DC power source dedicated to high-voltage output with a reverse bias is switched by a relay will be described. Specifically, in the sixth embodiment, an example will be described in which the DC power source dedicated to the high-voltage output with the reverse bias is switched by the relay in the power source configuration of the fourth embodiment. In the following, differences from the fourth embodiment will be mainly described, and components having the same functions as those in the fourth embodiment will be given the same names and symbols as those in the fourth embodiment, and the description thereof will be made. Omitted. However, constituent elements having the same functions as those of the third embodiment even with differences from the fourth embodiment are denoted by the same names and symbols as those of the third embodiment, and the description thereof is omitted.

  FIG. 18 is a block diagram illustrating an example of an electrical configuration of a printing apparatus 901 according to the sixth embodiment. As shown in FIG. 18, in the printing apparatus 901 of the sixth embodiment, the secondary transfer power supply 1000 is different from the printing apparatus 601 of the fourth embodiment.

  FIG. 19 is a block diagram illustrating an example of an electrical configuration of the secondary transfer power supply 1000 according to the sixth embodiment. As shown in FIG. 19, the secondary transfer power supply 1000 of the sixth embodiment is different from the fourth embodiment in that it further includes a DC relay 545.

  The DC relay 545 is a relay that switches whether or not to output DC high voltage to the secondary transfer unit facing roller 63, and is switched on / off by a DCRY signal input from the I / O control unit 110. When the DC relay 545 is on, the DC high voltage output from the output unit 237 is performed to the secondary transfer unit facing roller 63.

  As described above, in the secondary transfer power supply 1000 according to the sixth embodiment, whether or not high voltage output with a reverse bias is performed with respect to the secondary transfer unit facing roller 63 is switched by a relay.

  Note that the engine control unit 400 of the printing apparatus 901 of the sixth embodiment is the same as that of the third embodiment, and the transfer control process when high voltage output is performed with a superimposed bias is the same as that of the third embodiment. That is, FIG. 14 is a timing chart when high voltage output is performed with the superimposed bias.

  As described above, the sixth embodiment also has the same effect as the third embodiment.

(Hardware configuration)
The printing apparatus according to each of the embodiments includes a control device such as a CPU, a storage device such as a ROM and a RAM, an external storage device such as an HDD and an SSD, a display device such as a display, and an input device such as a mouse and a keyboard. And a communication device such as a communication I / F, and has a hardware configuration using a normal computer.

  The program executed by the printing apparatus according to each of the above embodiments is an installable or executable file that can be read by a computer such as a CD-ROM, CD-R, memory card, DVD, or flexible disk (FD). Stored in a different storage medium.

  The program executed by the printing apparatus of each of the above embodiments may be provided by storing it on a computer connected to a network such as the Internet and downloading it via the network. The program executed by the printing apparatus according to each of the above embodiments may be provided or distributed via a network such as the Internet. The program executed by the printing apparatus of each of the above embodiments may be provided by being incorporated in advance in a ROM or the like.

  The program executed by the printing apparatus according to each of the above embodiments has a module configuration for realizing the above-described units on a computer. As actual hardware, for example, the CPU reads out a program from the ROM to the RAM and executes the program, whereby the above-described units are realized on the computer.

(Modification)
In addition, this invention is not limited to said each embodiment, A various deformation | transformation is possible.

(Modification 1)
In each of the above embodiments, various timings are specified based on the print start reference signal and the start / end of the print job, but the timing specifying method is not limited to this. For example, any timing may be specified based on the print start reference signal, and another timing may be specified based on the specified timing.

(Modification 2)
In each of the above-described embodiments, examples have been described in which high voltage output is performed using a superimposed bias in which a DC voltage and an AC voltage are superimposed when an image is transferred to recording paper with large unevenness such as a resack paper, but the present invention is not limited to this. is not. When an image is transferred onto a recording sheet having large unevenness, for example, high voltage output using only an AC voltage (AC bias) may be performed, or at least high voltage output using an AC voltage may be performed.

(Modification 3)
In each of the above embodiments, the example in which the transfer bias is applied by connecting the transfer bias secondary transfer power source to the secondary transfer unit facing roller 63 has been described. However, the transfer bias secondary transfer power source is the secondary transfer roller. The toner image can be transferred to the recording paper without any problem even if the transfer bias is applied by connecting to 64. Further, for example, even when one of the secondary transfer power sources for transfer bias is connected to the secondary transfer portion facing roller 63 and the other is connected to the secondary transfer roller 64, the toner image can be transferred onto the recording paper without any problem. it can.

(Modification 4)
In each of the above embodiments, the output timing of the high-voltage output is specified by software, but may be specified by hardware.

(Modification 5)
For example, as shown in FIG. 20, a medium resistance transfer roller 1102 is brought into contact with the photosensitive drum 1103, a bias is applied to the transfer roller 1102 from the power source 1101, the toner is transferred to the paper 1104, and the paper 1104 is conveyed. In the configuration, the power source 1101 may adopt the same power source configuration as that of the above embodiments.

  The configuration of the image forming unit having the photosensitive drum 1103 and the like is the same as that of each of the above embodiments, and the transfer roller 1102 has a resistance layer made of a conductive sponge formed on a cored bar made of stainless steel, aluminum, or the like. Is done. A surface layer made of a fluororesin or the like may be provided on the surface of the resistance layer.

  Further, the photosensitive drum 1103 and the transfer roller 1102 are in contact with each other to form a transfer nip (not shown). The photosensitive drum 1103 is grounded, the transfer roller 1102 is connected to a power source 1101, and a transfer bias is applied. As a result, a transfer electric field for electrostatically moving toner from the photosensitive drum 1103 toward the transfer roller 1102 is formed between the photosensitive drum 1103 and the transfer roller 1102, and the toner image on the photosensitive drum 1103 is The image is transferred to the paper 1104 sent out toward the transfer nip by the action of the transfer electric field or nip pressure.

(Modification 6)
For example, as shown in FIG. 21, in a configuration in which a medium resistance transfer belt 1204 is brought into contact with a photosensitive drum, a bias is applied to the transfer belt 1204 from a power source 1201, toner is transferred to a sheet, and the sheet is conveyed. The power supply 1201 may employ the same power supply configuration as that of the above embodiments.

  Note that the configuration of the image forming unit having the photosensitive drum and the like is the same as that in each of the above embodiments. The transfer belt 1204 is supported around the drive roller 1202 and the driven roller 1203, and travels in the direction indicated by the arrow in the drawing by the drive roller 1202. The transfer belt 1204 contacts the photosensitive drum at a position between the driving roller 1202 and the driven roller 1203. A transfer bias roller 1205 and a bias brush 1206 are provided inside the loop of the transfer belt 1204, and abut the belt at a position downstream of the region where the photosensitive drum and the transfer belt 1204 abut.

  In addition, a transfer nip (not shown) is formed by contacting the photosensitive drum and the transfer bias roller 1205. The photosensitive drum is grounded, and the transfer bias roller 1205 is connected to a power source 1201 to apply a transfer bias. As a result, a transfer electric field is formed between the photosensitive drum and the transfer bias roller 1205 to electrostatically move the toner from the photosensitive drum toward the transfer bias roller 1205, and the toner image on the photosensitive drum is transferred. The image is transferred to a sheet fed toward the transfer nip by the action of an electric field or nip pressure.

  Only one of the transfer bias roller 1205 and the bias brush 1206 may be provided. Further, either the transfer bias roller 1205 or the bias brush 1206 may be provided immediately below the transfer nip. Further, a transfer charger may be used in place of the transfer bias roller 1205 and the bias brush 1206.

(Modification 7)
For example, as shown in FIG. 22, CMYK color transfer rollers 1304C, 1304M, 1304Y, and 1304K are brought into contact with CMYK color photosensitive drums via a medium resistance transfer belt 1303, and transfer rollers 1304C, 1304M, 1304Y, And 1304K are biased from the power supplies 1301C, 1301M, 1301Y, and 1301K, the toner is transferred to the paper, and the paper is transported, and the power supplies 1301C, 1301M, 1301Y, and 1301K A configuration may be adopted.

  The configuration of each color image forming unit having the CMYK color photosensitive drums and the like is the same as in the above embodiments except that the toner colors are different.

  The transfer belt 1303 is supported around a plurality of rollers, and travels counterclockwise in the figure. The transfer belt 1303 is in contact with each photoconductor drum of each color. Transfer rollers 1304C, 1304M, 1304Y, and 1304K for each color are provided inside the loop of the transfer belt 1303, and abut against the transfer belt 1303 so as to face the photosensitive drums for each color.

  The transfer roller 1304C and the C-color photosensitive drum are in contact with each other to form a transfer nip. The C-color photosensitive drum is grounded, and the transfer roller 1304C is connected to a power source 1301C and applied with a transfer bias. A transfer bias is applied to the transfer roller 1304C by a power source 1301C. As a result, a transfer electric field for electrostatically moving the C-color toner from the C-color photosensitive drum toward the transfer roller 1304C is formed in the transfer nip. Note that the same operation as described above is performed in the photosensitive drums, transfer rollers, and power supplies of other colors.

  The sheet is conveyed from the lower right side of the figure, passes between the biased sheet adsorbing roller and the transfer belt 1303, is adsorbed to the transfer belt 1303, and is conveyed to the transfer nip of each color. The toner images of the respective colors on the photosensitive drum are sequentially transferred onto the paper conveyed to the transfer nip by the action of the transfer electric field and nip pressure, and a full color toner image is formed on the paper.

  Note that the power supplies 1301C, 1301M, 1301Y, and 1301K may not be prepared for each color, but may be a single power supply, and a bias may be applied to the transfer rollers 1304C, 1304M, 1304Y, and 1304K.

(Modification 8)
For example, as shown in FIG. 23, in a system in which a transfer charger 1402 and a separation charger 1404 are arranged in the vicinity of the photosensitive drum and the paper is transferred, separated, and conveyed, a bias is applied to the wire of the transfer charger 1402 from the power supply 1401. When applying, transferring the toner onto the paper, and transporting the paper, the power supply 1401 may employ a power supply configuration similar to that of each of the above embodiments.

  After passing through the registration roller 1403, the sheet is transferred by the transfer charger 1402, separated by the separation charger 1404, and conveyed to the fixing unit.

(Modification 9)
For example, as shown in FIG. 24, in a system in which the secondary transfer belt 1504 is brought into contact with the intermediate transfer belt 1502 to transfer and separate the paper, a bias is applied from the power source 1501 to the opposing roller 1503 to supply toner. When transferring to a sheet and transporting the sheet, the power supply 1501 may employ a power supply configuration similar to that of each of the above embodiments.

  The configuration of each color image forming unit having the CMYK color photosensitive drums and the like is the same as in the above embodiments except that the toner colors are different.

  The secondary transfer belt 1504 is supported around a driving roller 1505 and a driven roller 1506, and travels counterclockwise in the drawing by the driving roller 1505. The secondary transfer belt 1504 is in contact with the intermediate transfer belt 1502.

  The secondary transfer belt 1504 and the intermediate transfer belt 1502 are in contact with each other to form a secondary transfer nip. The driving roller 1505 is grounded, and the opposing roller 1503 is connected to a power source 1501 to apply a transfer bias. As a result, a transfer electric field for electrostatically moving the toner from the intermediate transfer belt 1502 toward the secondary transfer belt 1504 is formed in the secondary transfer nip. The toner image on the intermediate transfer belt 1502 is transferred to the paper that has entered the secondary transfer nip by the action of the secondary transfer electric field and nip pressure.

  The counter roller 1503 may be grounded, and a roller C may be provided, and a power supply 1501 may be connected to the roller C to apply a transfer bias.

(Modification 10)
Further, for example, in each of the above embodiments, a printing system including a server device in addition to the printing device may be used, and the server device may include a power control unit.

  FIG. 25 is an external view illustrating an example of the printing system 2000 according to the tenth modification. The printing system 2000 is a production printing machine and includes a server device 2020. The server device 2020 corresponds to, for example, an external controller called an external server or DFE (Digital Front End). The printing system 2000 includes a printing apparatus 2001, a large-capacity paper feeding unit 2002 that feeds paper, an inserter 2003 that is used to use a cover, a folding unit 2004 that performs folding, a finisher 2005 that performs stapling and punching, and cutting. Peripheral machines such as the cutting machine 2006 to be performed are combined in accordance with the application.

  FIG. 26 is a hardware configuration diagram illustrating an example of the server device 2020 according to the tenth modification. As shown in FIG. 26, the server device 2020 includes a communication I / F unit 2030, a storage unit 2040 (HDD 2042, ROM 2044, RAM 2046), an image processing unit 2050, a CPU 2090, and an I / F unit 2060. Each is connected to each other by a bus B2. The CPU 2090 includes a power supply control unit 2091.

  In the example of FIG. 26, the server apparatus 2020 is connected to the printing apparatus 2001 via a dedicated line 2100. However, the connection form between the server apparatus 2020 and the printing apparatus 2001 is not limited to this. For example, if the necessary communication speed between the server apparatus 2020 and the printing apparatus 2001 can be secured, the server apparatus 2020 and the printing apparatus 2001 are connected to each other via a network. You may connect via.

  As shown in FIG. 26, the printing apparatus 2001 includes an I / F unit 2110, a printing unit 2102, an operation display unit 2160, another I / F unit 2170, and a secondary transfer power supply 2180, each of which is a bus. Connected at B3. The I / F unit 2110 is means for connecting the printing device 2001 to the server device 2020, and a dedicated line 2100 is connected to the I / F unit 2110. The printing apparatus 2001 executes a print job under the control of the CPU 2090 of the server apparatus 2020.

  And the power supply control part 2091 mounted in the server apparatus 2020 performs the process which the power supply control part of the printing apparatus of each said embodiment is performing.

(Modification 11)
The above-described embodiments and modifications are examples, and it has been confirmed in other image forming apparatuses and various image forming environments that the present invention can be realized even if the configuration and process conditions are changed. .

1, 301, 401, 601, 801, 901 Printing device 10Y, 10M, 10C, 10K Image forming unit 11Y, 11M, 11C, 11K Photosensitive drum 20Y, 20M, 20C, 20K Charging device 30Y, 30M, 30C, 30K Development Device 31Y Container 32Y Development sleeve 33Y Screw member 40Y, 40M, 40C, 40K Primary transfer roller 50Y, 50M, 50C, 50K Cleaning device 51Y Cleaning blade 52Y Cleaning brush 60 Intermediate transfer belt 61, 62 Support roller 63 Opposing secondary transfer unit Roller 64 Secondary transfer roller 70 Paper cassette 71 Paper feed roller 72 Conveying roller pair 90 Fixing device 100, 300, 400 Engine control unit 110 I / O control unit 120 RAM
130, 330 ROM
140, 340, 440 CPU
142, 342, 442 Power supply control unit 200, 500, 700, 1000 Secondary transfer power supply 210, 710 Superimposed power supply 211 D / A converter 212 Drive unit 213 Booster 214 D / A converter 215 Driver 216 Booster 217 Output Unit 225 AC relay 230, 730 DC power supply 231 D / A conversion unit 232 drive unit 233 boost unit 234 D / A conversion unit 235 drive unit 236 boost unit 237 output unit 545 DC relay 711 D / A conversion unit 712 drive unit 713 Boosting unit 2000 Printing system 2002 Large capacity feeding unit 2003 Inserter 2004 Folding unit 2005 Finisher 2006 Cutting machine 2020 Server device 2030 Communication I / F unit 2040 Storage unit 2042 HDD
2044 ROM
2046 RAM
2050 Image processing unit 2060 I / F unit 2090 CPU
2091 Power supply control unit 2100 Dedicated line 2102 Printing unit 2110 I / F unit 2160 Operation display unit 2170 Other I / F unit 2180 Secondary transfer power supply B2 bus B3 bus

JP 2012-42835 A

Claims (6)

Transfer means for transferring a toner image to a transfer target;
Superimposed power supply means for outputting a superimposed voltage obtained by superimposing an AC voltage and a DC voltage;
Switching means for switching whether to apply the output superimposed voltage to the transfer means;
A power control unit that switches the switching unit to apply the superimposed voltage to the transfer unit when the superimposed voltage is output from the superimposed power source unit when the transfer unit is applied with the superimposed voltage ; Prepared ,
The power control means causes the superimposed power supply means to output the DC voltage at a first timing, causes the superimposed power supply means to output the AC voltage at a second timing, and is later than the first timing and the second timing. An image forming apparatus that switches the switching unit at a third timing . The power supply control means causes the superimposed power supply means to finish outputting the DC voltage and the AC voltage at a fourth timing that is later than the third timing, and prevents the superimposed voltage from being applied to the transfer means. The image forming apparatus according to claim 1 , wherein the switching unit is switched. The first timing, the second timing, the third timing, and the fourth timing, the image forming apparatus according to claim 1 or 2 a print start reference signal to timing as a reference. The power supply control means switches the switching means so that the superimposed voltage is not applied to the transfer means at a fourth timing that is later than the third timing, and the superimposed power supply means at a fifth timing that is later than the fourth timing. The image forming apparatus according to claim 1 , wherein the output of the DC voltage and the AC voltage is terminated. The first timing and the second timing are timings based on the start of a print job,
The third timing and the fourth timing are timings based on a print start reference signal,
The fifth timing, the image forming apparatus according to claim 1 or 4 is a timing relative to the end of the print job. An image forming system having an image forming apparatus,
The image forming apparatus includes:
Transfer means for transferring a toner image to a transfer target;
Superimposed power supply means for outputting a superimposed voltage obtained by superimposing an AC voltage and a DC voltage;
Switching means for switching whether to apply the output superimposed voltage to the transfer means;
With
The image forming system includes:
When applying the transfer means at the superimposed voltage, the power supply control means for switching the switching means so that the superimposed voltage is applied to the transfer means in a state where the superimposed voltage is output from the superimposed power supply means ,
The power control means causes the superimposed power supply means to output the DC voltage at a first timing, causes the superimposed power supply means to output the AC voltage at a second timing, and is later than the first timing and the second timing. An image forming system for switching the switching means at a third timing .

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