JP4617859B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus using an electrophotographic system such as a copying machine, a facsimile, a laser printer, and the like, and in particular, by applying a voltage having a predetermined voltage value to a transfer unit by constant voltage control, the potential of the transfer unit is set to a predetermined level. The present invention relates to an image forming apparatus that maintains a value.

  For example, in a laser printer which is an example of an image forming apparatus, for example, a print mode such as the number of prints, a paper size, and enlargement / reduction is set at the start of operation. The laser printer operates according to the set print mode and performs printing. The set print mode is cleared to an initial state in which the print mode is not set when the power input to the laser printer is stopped even for a short time.

  The state in which the power input to the laser printer is stopped may be due to an unexpected situation such as a power failure as well as a case of the user's judgment. Even after the power failure occurs, the print mode set in the laser printer is cleared by the power failure and returns to the initial state even if the power failure is restored. Therefore, the print mode must be set again from the beginning.

  To solve the above problem, the timekeeping means that operates at normal time by the uninterruptible power supply, the time data by the timekeeping means, and the operation mode data set prior to the start of the image forming operation are stored in the nonvolatile memory. And when the power is turned off to on, the power off time stored in the storage means is read, and when the time from the power off to on is within a predetermined time, the storage An image forming apparatus that restores the operation mode data stored in the means as the operation mode data set in the image forming apparatus has been proposed (see Patent Document 1).

  By the way, in the image forming apparatus, a charging roll as a charging unit or a photosensitive drum as an image carrier may have temperature characteristics. For example, when the charging roll has temperature characteristics, even if a proper image is obtained in an environment of about 20 ° C., if the charging roll is left in an environment of 10 ° C. or less for a long time, the temperature of the charging roll is also set. Similar temperature is reached. When the image forming process is performed at this time, the resistance value of the charging roll increases due to the temperature characteristics of the charging roll, and as a result, the amount of current decreases, and the dark potential (black background potential) and halftone potential of the photosensitive drum decrease. Is reduced, and the difference from the white background potential is reduced, so that the reproducibility of a thin character image such as a pencil image and a section is deteriorated.

  On the other hand, if the image forming conditions are set so that an appropriate image can be obtained in a low temperature environment, when the temperature reaches, for example, about 20 ° C., the resistance value becomes small due to the temperature characteristics of the charging roll, so that it flows to the charging roll. Since the amount of current increases and the surface potential of the photosensitive drum increases, an overall fogged image is obtained.

  The above-described problem also occurs due to a temperature rise in the image forming apparatus accompanying a large amount of continuous printing.

  Furthermore, troubles due to resistance fluctuations during a large amount of continuous printing occur not only in charging rolls but also in members such as transfer rolls as transfer means.

  For the above-mentioned problem, the charging voltage by the charging roll is controlled at a constant voltage, the current amount and the temperature in the environment where the image forming apparatus is placed are detected, and the voltage is detected according to the detected current amount. It has been proposed to suppress a change in the charging potential of the object to be charged accompanying an environmental change by performing constant voltage control of the charging voltage with correction corresponding to the temperature (see Patent Document 2).

Further, Patent Document 2 also describes a proposal for a problem during continuous printing. In Patent Document 2, when a pause time (switch-off time) of the image forming apparatus is detected by a time measuring unit and the pause time is a predetermined value or more, the temperature of the charging roll and the photosensitive drum is the same as that of the external environment. Determining the environmental temperature at which the image forming apparatus is placed and determining a correction value corresponding to the detected temperature by referring to a memory in which correction values corresponding to the respective temperatures are stored in advance. When the operating time of the image forming apparatus (the time actually used for the image forming operation) is integrated, and the time used within a certain time exceeds a certain value, the charging roll It is also described that it is determined that the temperature of the photosensitive drum has risen sufficiently and the temperature correction is canceled.
JP-A-7-146630 Japanese Patent No. 3286899

  However, in the above-mentioned proposal, in addition to the existing configuration, the time measuring means and a power source used for driving the time measuring means are required, and when the power supply from the power source is cut off, the time measured data disappears, and the pause is performed. I can't get the time accurately. In addition, since the time measuring means and the power source used for driving the time measuring means are required, it has been an obstacle to the space saving of the control board.

SUMMARY OF THE INVENTION In view of the above, without to add a new part to another existing configuration, and control without complicating the, even when the power during the image forming process is interrupted, the appropriate An object is to obtain an image forming apparatus that applies a voltage.

The invention of claim 1, the peripheral surface of orbiting forms a uniformly on the charged image bearing member, an electrostatic latent image by a difference in charge potential by irradiating image light based on image data by the charging means Exposing means; developing means for transferring toner to an electrostatic latent image formed by the exposing means to form a toner image; transferring means for transferring the toner image developed by the developing means to a recording paper; Voltage application means for applying a voltage to the transfer means so that a predetermined current flows through the transfer means ; storage means for storing the latest voltage value at the end of continuous image formation applied by the voltage application means ; a detecting means for detecting the temperature and humidity in the image forming apparatus, when restarting the continuous image formation, a voltage difference between the stored voltage values to said storage means and the value of the voltage applied by said voltage applying means in front Relationship to the temperature and humidity of an unused time of the image forming apparatus, a voltage value applied to said transfer means at the present time, and based on the detected temperature and humidity by the detecting means, unused said image forming apparatus And unused time determining means for determining time.

  As described above, the image forming apparatus described in claim 1 can determine the unused time without providing a means for directly measuring the unused time. For example, it is no longer possible to measure the unused time by shutting off the power, and an accurate unused time can always be obtained. Further, the space for the control board of the apparatus can be reduced and the cost can be reduced.

According to a second aspect of the present invention, when the unused time determination unit determines that the unused time of the image forming apparatus is equal to or greater than a first threshold when the continuous image formation is resumed, the predetermined voltage value is set. When the voltage is applied to the transfer unit with a corresponding voltage value, and the unused time of the image forming apparatus is less than or equal to the second threshold smaller than the first threshold when the continuous image formation is resumed, the unused time is When judged by the judging means, a continuous image forming time and a voltage value applied to the transferring means in order to keep the transfer potential of the transferring means constant during the continuous image forming are configured to be associated in advance. A voltage is applied to the transfer unit with reference to the table, and when the continuous image formation is resumed, the unused time of the image forming apparatus exceeds the second threshold and is less than the first threshold. When determined by the use time determining unit, the voltage applying unit applies the voltage to the transfer unit with an average voltage value of the voltage value stored in the storage unit and the voltage value at the start of image formation. It further has a control means for controlling .

As mentioned above has been described, the present invention is not to add a new part to another existing configuration, and control without complicating the, even when the power during the image forming process is interrupted, the appropriate It has an excellent effect of obtaining an image forming apparatus that applies voltage.

  An embodiment of an image forming apparatus according to the present invention will be described with reference to the drawings.

  FIG. 1 shows a schematic configuration of an IOT (Image Output Terminal) 12 provided in the laser printer 10. In addition, the arc-shaped arrow shown in FIG. 1 has shown the rotation direction of the corresponding rotation member.

  The IOT 12 of the laser printer 10 includes an image forming unit 14 including photosensitive drums 16 (16Y, 16M, 16C, and 16K) for each color of yellow (Y), magenta (M), cyan (C), and black (K). (14Y, 14M, 14C, 14K), a charger 18 (18Y, 18M, 18C, 18K) for primary charging that contacts the corresponding photosensitive drum 16, and laser light for each color of Y, M, C, K And 20 (20Y, 20M, 20C, 20K) to the corresponding photosensitive drum 16 and a laser optical unit (not shown).

  The IOT 12 includes a developing unit 22 (22Y, 22M, 22C, and 22K) that stores a developer containing toner of each color component, and a primary intermediate transfer roll 24A and a photosensitive drum 16C that are in contact with the photosensitive drums 16Y and 16M. , A primary intermediate transfer roll 24B in contact with 16K, a secondary intermediate transfer roll 26 in contact with the primary intermediate transfer rolls 24A, 24B, and a final transfer roll 28 in contact with the secondary intermediate transfer roll 26. ing.

  In the laser printer 10 according to the present embodiment, the process cartridge in which the photosensitive drum 16, the charger 18, the developing device 22, the primary intermediate transfer rolls 24A and 24B, and the secondary intermediate transfer roll 26 are integrally mounted. (CRU: Customer Replaceable Unit).

  The photosensitive drums 16 are arranged at regular intervals along the vertical direction (the vertical direction in the drawing of FIG. 2). Further, the primary intermediate transfer rolls 24 </ b> A and 24 </ b> B and the secondary intermediate transfer roll 26 are arranged so that the respective rotation axes are parallel to the rotation axis of the photosensitive drum 16.

  In the laser optical unit, the laser light 20 of each color is modulated in accordance with the image information for each color input from the image processing unit (not shown), and each photoconductor drum 16 is irradiated with the laser light 20 corresponding to each color. Around the drum 16, an image forming process for each color by a known electrophotographic method is performed as follows.

  At this time, each photosensitive drum 16 is rotationally driven at a predetermined rotational speed (for example, 95 mm / sec), and first, a DC voltage of a predetermined charging level (for example, about −800 V) is applied to the charger 18 on the surface. As a result, it is uniformly charged to a predetermined level. In the present embodiment, only a DC voltage may be applied to the charger 18, or an AC component may be superimposed on the DC component.

  Next, laser light 20 corresponding to each color is irradiated onto the surface of each photosensitive drum 16 having a uniform surface potential by a laser optical unit, and an electrostatic latent image corresponding to image information for each color is formed. The

  As a result, the surface of the photosensitive drum 16 is discharged to a predetermined level (for example, about −58 V or less) at the surface portion exposed by the laser beam.

  The electrostatic latent image formed on the surface of each photoconductive drum 16 is developed by the corresponding developing device 22, and the electrostatic latent image is visualized on each photoconductive drum 16 as a toner image of each color.

  Next, the toner images of the respective colors formed on the respective photosensitive drums 16 are obtained by transferring the Y and M toner images formed on the photosensitive drums 16Y and 16M to the primary intermediate transfer roll 24A, the photosensitive drums 16C and 16C, The toner images of C color and K color formed on 16K are primary transferred electrostatically onto the primary intermediate transfer roll 24B.

  Note that a transfer bias power source (not shown) is connected to the primary intermediate transfer rolls 24A and 24B, and at the time of primary transfer of the toner image, a transfer bias is transferred from the transfer bias power source to the primary intermediate transfer rolls 24A and 24A. Applied to each of 24B.

  The toner images formed on the primary intermediate transfer rolls 24A and 24B are electrostatically secondarily transferred onto the secondary intermediate transfer roll 26. As a result, a toner image from a single color image to a quadruple color image of each of Y, M, C, and K is formed on the secondary intermediate transfer roll 26.

  A transfer bias power source is also connected to the secondary intermediate transfer roll 26 in the same manner as the primary intermediate transfer rolls 24A and 24B, and a transfer bias is applied to the secondary intermediate transfer roll 26 during the secondary transfer of the toner image. Is done.

  The toner image formed on the secondary intermediate transfer roll 26 is tertiary-transferred (final transfer) to the paper 36 passing through the paper conveyance path 30 by the final transfer roll 28. This paper 36 is applied as a recording paper, and the paper 36 passes through a paper transporting roll 32 through a paper feeding process (not shown), and a nip portion between the secondary intermediate transfer roll 26 and the final transfer roll 28. Is sent to. After the tertiary transfer, the toner image formed on the paper 36 is fixed by the fixing device 34, and the image forming process is completed. The final transfer roll 28 is also connected to a transfer bias power source in the same manner as the primary intermediate transfer rolls 24A, 24B and the secondary intermediate transfer roll 26, and the transfer bias power supply is transferred from the transfer bias power supply during the third transfer of the toner image. Is applied to the final transfer roll 28.

  The charger 18 according to the present embodiment includes a charging roll 38 for charging the photosensitive drum 16 and a brush roll 40 on the upstream side of the charging roll 38, and the photosensitive drum 16 is configured by the brush roll 40. Foreign matter such as residual toner and carrier is removed to prevent the foreign matter on the photosensitive drum 16 from being transferred to the charging roll 38 side.

  Further, the primary intermediate transfer rolls 24A and 24B and the secondary intermediate transfer roll 26 are arranged in contact with the primary intermediate brush rolls 42A and 42B and the secondary intermediate brush roll 44, and the residual toner adhered to the surface of each roll. Etc. are temporarily held.

  Further, the final transfer roll 28 is provided with a cleaning device 46 having a blade 46A and adopting a blade cleaning method.

  Next, the electrical system of the laser printer 10 according to the present embodiment will be described with reference to FIG.

  The laser printer 10 includes a static elimination needle 48 that neutralizes the photosensitive drum 16, the charging roll 38, the developing device 22, the primary intermediate transfer rolls 24 </ b> A and 24 </ b> B, the secondary intermediate transfer roll 26, and the final transfer roll 28. A high voltage power supply 50 for supplying power is provided.

  The high-voltage power supply 50 supplies a power to the charge removal power supply circuit 52 for supplying power to the charge removal needle 48, a power supply circuit 54 for charging to supply power to the roll 38, and power to the developing unit 22. Development power supply circuit 56, primary transfer power supply circuit 58 for supplying power to the primary intermediate transfer rolls 24A and 24B, and secondary transfer power supply circuit 60 for supplying power to the secondary intermediate transfer roll 26. And a final transfer power supply circuit 62 for supplying power to the final transfer roll 28.

  Further, the laser printer 10 includes a control unit 64 that controls the power supply of the high voltage power supply 50.

  The control section includes a charge removal voltage control section 68 that controls the discharge power supply circuit 52, a charge voltage control section 70 that controls the charge power supply circuit 54, and a development voltage control that controls the development power supply circuit 56. 72, a primary transfer voltage control unit 74 for controlling the primary transfer power supply circuit 58, a secondary transfer voltage control unit 76 for controlling the secondary transfer power supply circuit 60, and the final transfer power supply circuit 62. A voltage control unit 66 including a final transfer voltage control unit 78. (Hereinafter, a high voltage is used to collectively refer to the static elimination power supply circuit 52, the charging power supply circuit 54, the development power supply circuit 56, the primary transfer power supply circuit 58, the secondary transfer power supply circuit 60, and the final transfer power supply circuit 62. The power supply 50, the charge-removing voltage control unit 68, the charging voltage control unit 70, the development voltage control unit 72, the primary transfer voltage control unit 74, the secondary transfer voltage control unit 76, and the final transfer voltage control unit. 78 is collectively referred to as voltage control unit 66).

  The final transfer power supply circuit 62 applies a voltage to the final transfer roll 28 under the control of the final transfer voltage controller 78, and a current that detects a current output from the constant voltage output circuit 62A. A detection circuit 62B is provided.

  The final transfer voltage control unit 78 determines whether or not the voltage value corresponding to the detected current value matches the planned voltage value. When the voltage value corresponding to the detected current value does not match the planned voltage value, the voltage output from the constant voltage output circuit 62A is corrected.

  That is, when the detected voltage value is larger than the planned voltage value, the transfer voltage is lowered. On the other hand, when the detected current value is smaller than the scheduled current value, the transfer voltage is increased. By correcting the transfer voltage in this way, the output current can be kept constant.

  By the way, when continuous printing is performed by the laser printer 10, each member such as the charging roll 38, the primary intermediate transfer rolls 24 </ b> A and 24 </ b> B, and the secondary intermediate transfer roll 26 may change in resistance due to the temperature rise in the apparatus and the influence of energization characteristics. Wake up. For this reason, as shown in FIG. 3, the surface potential of the intermediate transfer rolls such as the photosensitive drum 16, the primary intermediate transfer rolls 24A and 24B, the secondary intermediate transfer roll 26, and the final transfer roll 28 changes with continuous printing. I know you will. That is, it is necessary to apply different voltages to the members at the start of printing and at the end of continuous printing. The time reference voltage table 80 stores a relationship between a known continuous printing time and an applied voltage value for keeping the surface potential constant.

  The time reference voltage table 80 is connected to a reference voltage correction unit 82. On the other hand, the reference voltage correction unit 82 is connected to the voltage control unit 66. The reference voltage correction unit 82 refers to the time reference voltage table 80 and corrects the voltage value applied to the IOT 12 by the high voltage power supply 50 controlled by the voltage control unit 66.

  Further, the reference voltage correction unit 82 is connected to a temperature sensor 88A for detecting the temperature in the laser printer 10 and a humidity sensor 88B for detecting humidity. Accordingly, the reference voltage correction unit 82 can always grasp the environmental temperature and the environmental humidity when forming an image on the recording paper. Thus, the reference voltage correction unit 82 can correct the voltage value in consideration of the environmental temperature and the environmental humidity.

  Incidentally, the final transfer voltage control section 78 is connected to the voltage value storage section 84 and the voltage value comparison section 86, and outputs a voltage value corresponding to the current value detected by the current detection circuit 62B. . The voltage value storage unit 84 stores the output voltage value, and the final transfer voltage control unit 78 performs voltage control based on the past voltage value stored in the voltage value storage unit 84. The voltage value storage unit 84 is a non-volatile memory, and the stored content is not lost even when the power is turned off.

  The voltage value storage unit 84 also outputs the past voltage value to be stored to the voltage value comparison unit 86. The voltage value output from the voltage value storage unit 84 to the voltage value comparison unit 86 is a voltage value that serves as a basis for controlling the voltage value output from the final transfer voltage control unit 78. The voltage value comparison unit 86 compares the past voltage value output from the voltage value storage unit 84 with the voltage value output from the final transfer voltage control unit 78.

  The difference between the voltage values of the final transfer roll 28 obtained by the comparison of the voltage value comparison unit 86 is output to the reference voltage correction unit 82. The relationship between the unused time, the past voltage value output from the voltage value storage unit 84, and the voltage value output from the final transfer voltage control unit 78 is determined for each environmental temperature and environmental humidity. Yes. The reference voltage correction unit 82 determines the unused time of the laser printer 10 according to the voltage difference, the environmental temperature, and the environmental humidity, and the voltage control unit 66 applies the high voltage power supply 50 to the IOT 12 according to the unused time. The unused time correction for correcting the voltage value is performed.

  Thus, the unused time of the laser printer 10 can be determined from the difference between the past voltage value output from the voltage value storage unit 84 and the voltage value output from the final transfer voltage control unit 78.

  Here, with reference to FIG. 4, the elapsed time according to the present embodiment, the voltage value (V0) stored in the voltage value storage unit 84, the voltage value (V1) output from the final transfer voltage control unit 78, and The relationship with the surface potential (V2) of the secondary intermediate transfer roll 26 is shown.

  The time indicated by 0 on the horizontal axis in the figure is the printing start time, the time indicated by T1 is the printing end time, and continuous printing is performed from the time indicated by 0 to the time indicated by T1. . From the time point indicated by 0 to the time point indicated by T1, the process voltage correction is performed by the reference voltage correction unit 82 so that a low voltage is gradually applied. V0 and V1 have substantially the same inclination, and V2 is kept constant by correcting the voltage applied to the secondary intermediate transfer roll 26.

  T2 is the time when continuous printing is started again. The time from T1 to the time indicated by T2 is a sufficiently long unused time, for example, from the end time to the start time of the next day. Thus, when the time point indicated by T1 to the time point indicated by T2 is sufficiently long, the process progress correction by the reference voltage correction unit 82 is not necessary.

  At time T2, first, the final transfer voltage control unit 78 performs new voltage control. However, since the unused time from T1 is long, the voltage value to be actually applied to the final transfer roll 28 is the same as that at the time of zero. Therefore, the voltage value output from the final transfer voltage controller 78 (that is, the voltage value corresponding to the detected current value output from the current detection circuit 62B) is a value far from V0T1 as indicated by V1T2. become.

  Subsequently, the voltage value comparison unit 86 compares the V0T1 and V1T2. Based on the absolute value (ΔV = | V0T1-V1T2 |) of the difference between the voltage values obtained by the voltage value comparison unit 86, the reference voltage correction unit 82 determines that a sufficiently long unused time has elapsed since the previous use. Then, the unused time correction is performed so that the surface potential of the secondary intermediate transfer roll 26 becomes the same as when the surface potential is zero.

  Table 1 corresponds to the difference (ΔV) between the past voltage value output from the voltage value storage unit 84 and the voltage value output from the final transfer voltage control unit 78 under the low temperature and low humidity conditions. An embodiment of charging roll voltage correction control and intermediate transfer roll voltage correction control corresponding to the unused time under the unused time and the low temperature and low humidity will be described.

  Table 2 shows the difference (ΔV) between the past voltage value output from the voltage value storage unit 84 and the voltage value output from the final transfer voltage control unit 78 under normal temperature and low humidity. An embodiment of charging roll voltage correction control and intermediate transfer roll voltage correction control corresponding to the unused time corresponding to the unused time and the unused time under normal temperature and low humidity will be described.

  As shown in Tables 1 and 2, the larger the voltage value difference (ΔV), the longer the unused time, and the lower the temperature, the larger the voltage value difference (ΔV) with respect to the unused time.

  When the unused time is short (when the environmental temperature is 20 ° C. and the environmental humidity is 15%, 0.0 hours to 2.0 hours / when the environmental temperature is 10 ° C. and the environmental humidity is 15%, 0.0 hours to 2.0 hours), the reference voltage correction unit 82 does not perform the unused time correction for correcting the applied voltage controlled by the voltage control unit 66, and continues the process progress correction.

  When the unused time is long (when the environmental temperature is 20 ° C. and the environmental humidity is 15%, 7.0 hours to 12.0 hours / when the environmental temperature is 10 ° C. and the environmental humidity is 15%, 6.0 hours to 12.0 hours), the reference voltage correction unit 82 performs unused time correction using the applied voltage controlled by the voltage control unit 66 as the printing start voltage stored in the time reference voltage table 80.

  The middle of the case where the unused time is short and long (when the environmental temperature is 20 ° C. and the environmental humidity is 15%, 2.5 hours to 6.0 hours / the environmental temperature is 10 ° C. and the environmental humidity is 15%, (2.5 hours to 5.0 hours), the reference voltage correction unit 82 sets the applied voltage controlled by the voltage control unit 66 to an intermediate value from the printing start voltage stored in the time reference voltage table 80. (That is, correction voltage value = (applied voltage + printing start voltage) / 2).

  Next, the operation of the present embodiment will be described with reference to the flowchart of FIG. It is assumed that the environmental temperature is 20 ° C. and the environmental humidity is 15%.

  First, in step 100, the final transfer voltage control unit 78 acquires a past voltage value (V 0) stored from the voltage value storage unit 84.

  Subsequently, the process proceeds to step 102. In step 102, the final transfer voltage control unit 78 performs voltage control, and the constant voltage output circuit 62 </ b> A applies a voltage to the final transfer roll 28.

  Subsequently, the routine proceeds to step 104. In step 104, the current detection circuit 62B detects the current (A1) output from the constant voltage output circuit 62A. The voltage value (V1) corresponding to A1 is output to the voltage value comparison unit 86. On the other hand, the voltage value comparison unit 86 acquires V0 from the voltage value storage unit 84.

  Subsequently, the routine proceeds to step 106. In step 106, the voltage value comparison unit 86 obtains a difference (ΔV) between V1 and V0.

  Then, the process proceeds to step 108. In step 108, the reference voltage correction unit 82 obtains the unused time of the laser printer 10 based on ΔV obtained by the voltage value comparison unit 86.

  Then, the process proceeds to step 110. In step 110, the unused time falls within any range of A (0.0 hours to 2.0 hours), B (2.5 hours to 6.0 hours), and C (7.0 hours to 12.0 hours). Judge whether to enter.

  If the unused time falls within the range A in step 110, the process proceeds to step 112. In step 112, the reference voltage correction unit 82 does not perform the unused time correction for correcting the applied voltage controlled by the voltage control unit 66, and continues the process progress correction.

  If the unused time is in the range of B in step 110, the process proceeds to step 114. In step 114, the reference voltage correction unit 84 corrects the applied voltage controlled by the voltage control unit 66 to an intermediate value with the printing start voltage stored in the time reference voltage table 80 (that is, correction voltage value = (Applied voltage + printing start voltage) / 2).

  If the unused time falls within the range C in step 110, the process proceeds to step 116. In step 116, the reference voltage correction unit 82 performs unused time correction in which the applied voltage controlled by the voltage control unit 66 is corrected to the printing start voltage stored in the time reference voltage table 80.

  Then, the process proceeds to step 118. In step 118, the high voltage power supply 50 applies a voltage to each member of the IOT 12 under the control of the voltage control unit 66.

  Then, the process proceeds to step 120. In step 120, the applied voltage value controlled by the final transfer voltage control unit 78 is stored in the voltage value storage unit 84.

  The embodiments described above do not limit the configuration of the present invention. For example, in the embodiment, the laser printer 10 that forms an image on the sheet 36 through the photosensitive drum 16, the primary intermediate transfer rolls 24A and 24B, and the secondary intermediate transfer roll 26 has been described as an example. The present invention is not limited to this, and an arbitrary transfer image can be formed by transferring a toner image onto various recording papers such as paper 36 by an electrophotographic process using an intermediate transfer member having a conventionally known structure such as a primary intermediate transfer roll or an intermediate transfer belt. It can be applied to the image forming apparatus having the configuration as described above.

FIG. 2 is a schematic diagram illustrating a mechanism for performing image forming processing of the image forming apparatus according to the present embodiment. 1 is a block diagram of an electrical system of an image forming apparatus according to the present embodiment. It is a figure which shows the change of the surface potential at the time of continuous printing with a photoconductor drum and an intermediate transfer body roll. It is a figure which shows the relationship between the elapsed time which concerns on this Embodiment, the applied voltage to a last transfer roll, and a surface potential. It is a flowchart which shows the flow of the voltage correction control which concerns on this Embodiment.

Explanation of symbols

10 Laser printer (image forming device)
12 IOT
16 Photosensitive drum (image carrier)
20 Laser light (exposure means)
22 Developer (Developer)
24A, 24B Primary intermediate transfer roll (transfer means)
26 Secondary intermediate transfer roll (transfer means)
28 Final transfer roll (transfer means)
38 Charging roll (charging means)
50 High-voltage power supply 52 Static elimination power supply circuit 54 Charging power supply circuit 56 Development power supply circuit 58 Primary transfer power supply circuit 60 Secondary transfer power supply circuit 62 Final transfer power supply circuit 62A Constant voltage output circuit 62B Current detection circuit 64 Control unit 66 Voltage control unit 68 Static elimination voltage control unit 70 Charging voltage control unit (correction means)
72 Development Voltage Controller 74 Primary Transfer Voltage Controller (Correction Unit)
76 Secondary transfer voltage controller (correction means)
78 Final transfer voltage control section (constant voltage control means)
80 hour reference voltage table 82 Reference voltage correction unit (unused time judging means, environment judging means)
84 Voltage value storage unit (storage means)
86 Voltage value comparison unit (unused time judging means)
88A Temperature sensor 88B Humidity sensor

Claims (2)

The uniformly charged image bearing member by the peripheral surface of orbiting charging means, an exposure means for forming an electrostatic latent image by a difference in charge potential by irradiating image light based on image data,
Developing means for transferring toner to the electrostatic latent image formed by the exposure means to form a toner image;
Transfer means for transferring the toner image developed by the developing means to a recording paper;
Voltage application means for applying a voltage to the transfer means so that a predetermined current flows through the transfer means ;
Storage means for storing a voltage value at the end of the latest continuous image formation applied by the voltage application means ;
Detection means for detecting temperature and humidity in the image forming apparatus;
To resume the continuous image formation, the relationship with respect to temperature and humidity of an unused time of the voltage difference between the image forming apparatus of the stored voltage values to said storage means and the value of the voltage applied by said voltage applying means An unused time determination unit that determines an unused time of the image forming apparatus based on a voltage value currently applied to the transfer unit and a temperature and humidity detected by the detection unit;
An image forming apparatus comprising:   When the unused time of the image forming apparatus is determined to be equal to or greater than a first threshold when the continuous image formation is resumed, the transfer is performed with a voltage value corresponding to the predetermined voltage value. A voltage is applied to the means, and when the continuous image formation is resumed, the unused time determining means determines that the unused time of the image forming apparatus is equal to or less than a second threshold value that is smaller than the first threshold value. The continuous image formation time and a voltage value applied to the transfer unit in order to keep the transfer potential of the transfer unit constant during the continuous image formation with reference to a table configured in advance, When the voltage is applied to the transfer unit, and the unused time of the image forming apparatus exceeds the second threshold and is less than the first threshold when the continuous image formation is resumed, the unused time determination unit Therefore, if determined, control for controlling the voltage application unit so that a voltage is applied to the transfer unit with an average voltage value of the voltage value stored in the storage unit and the voltage value at the start of image formation. 2. The image forming apparatus according to claim 1, further comprising means.

Images