Image forming apparatus, voltage application method and program

Abstract

To provide an image forming apparatus that, when voltage is applied to at least a first rotating member of the first rotating member and a second rotating member to form the potential difference between both members and an image forming operation is executed, can prevent an image defect caused by a situation where the voltage applied to the first rotating member does not become zero while the image formation is stopped, a voltage application method executed in the apparatus, and a program.SOLUTION: An image forming apparatus 1 comprises: a first rotating member 19; a second rotating member 14 that is in contact with the first rotating member while image formation is stopped; and application means 200 that applies voltage to the first rotating member 19 during the image formation, and when the image formation is stopped, applies voltage having a polarity different from that during the image formation to the first rotating body 19.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to an image forming apparatus such as a copying machine, a printer, or a multi-function digital multifunction peripheral called an MFP, and a voltage application method and program executed in the apparatus. [Background technology]

[0002] In an image forming apparatus, during an image formation operation, a voltage is applied to at least the first of the first and second rotating members to create a potential difference between the two members, thereby executing the image formation process. For example, after a toner image formed on a photosensitive member is primarily transferred to an intermediate transfer belt by a primary transfer roller, when the toner image on the intermediate transfer belt is secondarily transferred to paper by a secondary transfer roller, a secondary transfer voltage of, for example, about 2000 V is applied to the secondary transfer roller.

[0003] Furthermore, in the standby state when image formation is stopped, the secondary transfer voltage is turned off and becomes zero, but in reality, a voltage of several volts may continue to be output due to error factors such as component variations. In this case, if the output state of a voltage of several volts continues for a long period of time while the intermediate transfer belt and secondary transfer roller are in contact, charge will remain on the intermediate transfer belt as transfer memory, and when the first print is made after standby, the image will not be transferred to the transfer memory area, resulting in a white band and poor image quality.

[0004] Furthermore, in addition to the relationship between the intermediate transfer belt and the secondary transfer roller, if the first and second rotating members are the primary transfer roller and intermediate transfer belt, and a voltage of several volts continues to be output to the primary transfer roller during standby after the primary transfer is complete, or if the first and second rotating members are the charging member and photosensitive member, or the developing member and photosensitive member, and the applied voltage to the charging member during standby after charging is complete, or to the developing member during standby after development is complete, does not become 0V, and a voltage output state of several volts continues for a long period of time, this can also cause image defects.

[0005] One way to solve this problem is to configure the two components, such as the intermediate transfer belt and the secondary transfer roller, to separate when image formation is stopped, or to provide a switching circuit to set the voltage to zero volts, but this would complicate the configuration and increase costs.

[0006] Patent Document 1 discloses an image forming apparatus that stops the AC output for development and performs a development operation during the next printing operation based on the stop time from the end of a printing operation to the start of the next printing operation.

[0007] Furthermore, Patent Document 2 discloses an image forming device that controls the output of a voltage generating unit applied to a load with a PWM signal while feeding back either a detected voltage value or a detected current value, and that executes protective control to stop the feedback control and forcibly change the PWM value if the other detected value falls below a predetermined threshold value.

[0008] Furthermore, Patent Document 3 discloses an image forming apparatus that measures the stop time of a photosensitive member and sets the polarity of the initial voltage to be applied to a developing device based on the stop time. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-007982 [Patent Document 2] Japanese Patent Application Laid-Open No. 2008-76750 [Patent Document 3] Japanese Patent Application Laid-Open No. 2016-142813 Summary of the Invention [Problem to be solved by the invention]

[0010] However, none of the image forming devices disclosed in the above-mentioned Patent Documents 1 to 3 mention the above-mentioned problem that occurs when the applied voltage to the first rotating member is set to zero when image formation is stopped, when an image forming operation is performed by applying a voltage to at least the first rotating member of the first and second rotating members to create a potential difference between the two members, and therefore do not provide a solution to these problems.

[0011] This invention has been made in consideration of this technical background, and aims to provide an image forming device, a voltage application method and a program executed by the device, which can prevent image defects caused by the applied voltage of the first rotating member not becoming zero when image formation is stopped, when an image forming operation is performed by applying a voltage to at least the first rotating member of a first rotating member and a second rotating member to form a potential difference between the two members. [Means for solving the problem]

[0012] The above object can be achieved by the following means: (1) a first rotating member; a second rotating member that contacts the first rotating member when image formation is stopped; a first voltage generating means capable of generating a voltage of a first polarity and a voltage of a second polarity; a second voltage generating means capable of generating a voltage of a second polarity; During image formation the voltage of the first polarity generated by the first voltage generating means and the voltage of the second polarity generated by the second voltage generating means are added together, the first rotating member Marked When the image formation is stopped, The output of the voltage of the second polarity by the second voltage generating means is stopped, and the first voltage generating means is set to output the voltage of the second polarity, and the output second voltage applying means for applying a voltage of a polarity to the first rotary member; An image forming apparatus comprising: (2) The image forming apparatus according to the above item 1, wherein the first rotating member is a secondary transfer roller, and the second rotating member is an intermediate transfer belt. (3) The image forming apparatus according to the above item 1, wherein the first rotating member is a primary transfer roller and the second rotating member is an intermediate transfer belt. (4) The image forming apparatus according to the above item (1), wherein the first rotating member is a charging member and the second rotating member is a photosensitive member. (5) The image forming apparatus according to the above item (1), wherein the first rotating member is a developing member and the second rotating member is a photosensitive member. ( 6 ) During image formation, the preceding paragraph includes at least one of the following: during printing operation, during stabilization operation, and during image patch printing. Any of 1 to 5 2. The image forming apparatus according to claim 1 . ( 7 ) When image formation is stopped, it means at least one of the following: when the image forming device is in standby mode, in energy saving mode, in service mode, in cleaning mode before printing starts or at the end of printing, or when the device is stopped due to a machine abnormality. Any of 1 to 6 2. The image forming apparatus according to claim 1 . ( 8 The applying means applies the voltage of the second polarity generated by the second voltage generating means to another member different from the first rotating member. Any of 1 to 7 2. The image forming apparatus according to claim 1 . ( 9 ) to the first rotating member of the first polarity When the application of voltage is stopped, the application means waits for a predetermined time to elapse after transitioning to a predetermined stop mode and then stops outputting. Any of 1 to 8 2. The image forming apparatus according to claim 1 . ( 10 ) to the first rotating member of the first polarity When the application of the voltage is resumed, the application means starts outputting the second voltage generating means for generating the voltage of the second polarity, and then starts outputting the first voltage generating means for generating the voltage of the first polarity. Any of 1 to 9 2. The image forming apparatus according to claim 1 . ( 11 ) a first rotating member; a second rotating member that contacts the first rotating member when image formation is stopped; a first voltage generating means capable of generating a voltage of a first polarity and a voltage of a second polarity; a second voltage generating means capable of generating a voltage of a second polarity; An image forming apparatus comprising: During image formation the voltage of the first polarity generated by the first voltage generating means and the voltage of the second polarity generated by the second voltage generating means are added together, the first rotating member Marked When the image formation is stopped, The output of the voltage of the second polarity by the second voltage generating means is stopped, and the first voltage generating means is set to output the voltage of the second polarity, and the output second voltage A voltage application method comprising: performing an application step of applying a voltage of a polarity to the first rotating member. (12 ) a first rotating member; a second rotating member that contacts the first rotating member when image formation is stopped; a first voltage generating means capable of generating a voltage of a first polarity and a voltage of a second polarity; a second voltage generating means capable of generating a voltage of a second polarity; A computer of an image forming apparatus including: During image formation the voltage of the first polarity generated by the first voltage generating means and the voltage of the second polarity generated by the second voltage generating means are added together, the first rotating member Marked When the image formation is stopped, The output of the voltage of the second polarity by the second voltage generating means is stopped, and the first voltage generating means is set to output the voltage of the second polarity, and the output second voltage a program for executing an application step of applying a voltage of a polarity to the first rotating member; [Effects of the Invention]

[0013] According to the invention described in the preceding paragraph (1), when the image formation by the image forming apparatus is stopped, the first rotating member and the second rotating member are in contact with each other, and in this state, the application portion of the first rotating member in contact with the second rotating member is applied with a voltage during image formation. A voltage of a first polarity is applied to is different from Second Since a voltage of the same polarity as that during image formation is applied, it is possible to reliably prevent a slight voltage of the same polarity as that during image formation from being applied to the application section of the first rotating member when image formation is stopped, thereby preventing image defects.

[0014] Furthermore, there is no need to provide a mechanism for separating the first rotating member from the second rotating member when image formation is stopped, or a switching circuit for setting the voltage applied to the first rotating member to zero volts, so the configuration does not become complicated and costs do not increase.

[0015] According to the invention described in the preceding paragraph (2), when image formation is stopped, it is possible to reliably prevent a slight voltage of the same polarity as that during normal image formation from being applied to the secondary transfer roller, thereby preventing the occurrence of transfer memory on the intermediate transfer belt and preventing image defects.

[0016] According to the invention described in the preceding paragraph (3), when image formation is stopped, it is possible to reliably prevent a slight voltage of the same polarity as that during normal image formation from being applied to the primary transfer roller, thereby preventing image defects.

[0017] According to the invention described in the preceding paragraph (4), when image formation is stopped, it is possible to reliably prevent a slight voltage of the same polarity as that during normal image formation from being applied to the charging roller, thereby preventing image defects.

[0018] According to the invention described in the preceding paragraph (5), when image formation is stopped, it is possible to reliably prevent a slight voltage of the same polarity as that during normal image formation from being applied to the developing roller, thereby preventing image defects.

[0020] Previous section ( 6 According to the invention described in (1), a voltage of a different polarity from the voltage applied during at least one of the printing operation, the stabilization operation, and the image patch printing is applied to the first rotating member when image formation is stopped.

[0021] Previous section ( 7 According to the invention described in (1), a voltage of a different polarity from that during image formation is applied to the first rotating member at least during one of the following times: when the image forming device is in standby mode, energy saving mode, service mode, cleaning mode before printing starts and at the end of printing, or when the machine is stopped due to an abnormality.

[0024] Previous section ( 8 According to the invention described in paragraph 1), the application section that generates the voltage of the second polarity can be used in common as the application section for the first rotating member and another member different from the first rotating member.

[0026] Previous section ( 9 According to the invention described in ), the first rotary member First polarity When the application of voltage is stopped, the application means transitions to a predetermined stop mode and then stops outputting after a predetermined time has elapsed.

[0027] Previous section ( 10 According to the invention described in ), the first rotary member First polarity When the application of voltage is resumed, the output of the voltage of the second polarity is started, and then the voltage of the first polarity is generated.

[0028] Previous section ( 11 According to the invention described in ), when image formation is stopped, the first rotary member and the second rotary member are in contact with each other, and in this state, the application section of the first rotary member that is in contact with the second rotary member is applied with a voltage during image formation. A voltage of a first polarity is applied to is different from Second Since a voltage of the same polarity as that during image formation is applied, it is possible to reliably prevent a slight voltage of the same polarity as that during image formation from being applied to the application section of the first rotating member when image formation is stopped, thereby preventing image defects.

[0029] Previous section ( 12 According to the invention described in , painting a second rotating member that contacts the first rotating member when image formation is stopped; a first voltage generating means capable of generating a voltage of a first polarity and a voltage of a second polarity, and a second voltage generating means capable of generating a voltage of the second polarity; a computer of an image forming apparatus including the First polarity When voltage is applied and image formation is stopped, the image formation is different from when image formation is in progress. Second An applying step of applying a voltage of a polarity to the first rotating member can be performed. [Brief explanation of the drawings]

[0030] [Figure 1] 1 is a schematic diagram illustrating the configuration of an image forming apparatus according to an embodiment of the present invention. [Figure 2] FIG. 2 is an enlarged view of a secondary transfer unit that transfers a toner image on an intermediate transfer belt onto a sheet of paper by a secondary transfer roller. [Figure 3] FIG. 2 is a diagram illustrating an example of the configuration of members arranged around a photosensitive member. [Figure 4] FIG. 2 is a configuration diagram of an application unit. [Figure 5]10 is a sequence diagram showing an example of transition of the output applied to the secondary transfer roller and the output applied to the static elimination needle. FIG. [Figure 6] 10 is a graph showing the output characteristics of a secondary transfer (+) transformer. [Figure 7] 10 is a graph showing the output characteristics of a static elimination transformer. DETAILED DESCRIPTION OF THE INVENTION

[0031] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0032] 1 is a schematic diagram of an image forming apparatus 1 according to an embodiment of the present invention. In this example, a tandem color printer is used as the image forming apparatus 1.

[0033] 1, the image forming apparatus 1 is configured such that a paper feed unit 20 is disposed at the bottom of the apparatus main body 1A, an image forming unit 10 is disposed in the center, and a paper discharge unit 60 is disposed at the top. The paper feed unit 20 is provided with a plurality of paper feed cassettes 21 (two in this example), and a paper transport path 22 is formed between each paper feed cassette 21 and the paper discharge unit 60 to transport paper S fed from the paper feed unit 20 upward.

[0034] The image forming unit 10 includes a drive roller 16 and a driven roller 15 arranged approximately in the vertical center of the device main body 1A, an intermediate transfer belt 14 suspended horizontally between the drive and driven rollers 16 and 15 and running in the direction of the arrow, photosensitive units 12Y, 12M, 12C, and 12K which are image forming units for each color of yellow (Y), magenta (M), cyan (C), and black (K) arranged along this running direction, and a secondary transfer roller 19, etc.

[0035] The toner images created by the photosensitive units 12Y, 12M, 12C, and 12K are superimposed and transferred onto the intermediate transfer belt 14, and secondary transfer is performed by the secondary transfer roller 19 at the conveying end (right end in the drawing) of the transfer belt 14 onto the paper S conveyed along the paper conveying path 22. The paper S is then sent to the fixing device 30 where the toner images are fixed. The fixing device 30 will be described later.

[0036] Each photoconductor unit 12Y, 12M, 12C, and 12K forms an image by electrostatic copying and includes a drum-shaped photoconductor 13Y, 13M, 13C, and 13K, charging devices 18Y, 18M, 18C, and 18K disposed around each photoconductor, developing devices 11Y, 11M, 11C, and 11K, and primary transfer rollers 17Y, 17M, 17C, and 17K, etc. The surfaces of each photoconductor 13Y, 13M, 13C, and 13K charged by charging devices 18Y, 18M, 18C, and 18K are exposed to light by the laser diodes of an exposure unit 40 that includes a print head 41 having four laser diodes, a polygon mirror, and a scanning lens, etc., and four reflecting mirrors 42, etc., so that an electrostatic latent image is formed on the surface.

[0037] In addition, toner cartridges 70Y, 70M, 70C, 70K and sub-hoppers 80Y, 80M, 80C, 80K are arranged above the photosensitive units 12Y, 12M, 12C, 12K as a supply mechanism for supplying toner to the developing devices 11Y, 11M, 11C, 11K of each photosensitive unit 12Y, 12M, 12C, 12K.

[0038] 1, reference numeral 50 denotes an operation panel unit equipped with hard keys and a display unit, and reference numeral 51 denotes a control unit. Although not shown, the control unit 51 includes a CPU, ROM, RAM, etc., and controls the overall operation of the image forming apparatus 1 by the CPU operating in accordance with an operating program stored in the ROM, etc.

[0039] FIG. 2 is an enlarged view of a secondary transfer section where a toner image on an intermediate transfer belt (corresponding to a second rotating member) 14 is transferred (printed) onto paper by a secondary transfer roller (corresponding to a first rotating member) 19.

[0040] The secondary transfer section includes a secondary transfer roller 19 pressed against the intermediate transfer belt 14 stretched over a drive roller 16, a separation claw 191 positioned above the drive roller 16, a charge removal needle 192 positioned downstream in the paper transport direction close to the secondary transfer roller 19, and a secondary transfer roller lock release lever 193.

[0041] When a sheet of paper passes between the intermediate transfer belt 14 and the secondary transfer roller 19, the toner image on the intermediate transfer belt 14 is transferred to the sheet of paper by the secondary transfer roller 19 to which a voltage is applied. The separation claw 191 separates the sheet of paper, which after transfer remains in close contact with the surface of the intermediate transfer belt 14 and attempts to move together with the intermediate transfer belt 191, from the intermediate transfer belt 14 and guides it in the original transport direction.

[0042] The charge eliminating needle 192 comes into contact with the paper that has passed through the secondary transfer roller 19 to eliminate static electricity from the paper, and a predetermined voltage is applied to the charge eliminating needle 192.

[0043] The secondary transfer roller lock release lever 193 is a lever that manually separates the secondary transfer roller 19 from the intermediate transfer belt 14 in the event of a paper jam or the like. The secondary transfer roller 19 and the intermediate transfer belt 14 are in contact with each other via the paper when paper is passing through, and are in direct contact when paper is not passing through.

[0044] 3 is a diagram showing an example of the configuration of the members arranged around the photoconductors 13Y, 13M, 13C, and 13K. Here, the photoconductor 13Y corresponding to yellow (Y) is shown as a representative example, but the configuration of the members around the other photoconductors 13M, 13C, and 13K is the same.

[0045] Arranged along the rotation direction of the photoreceptor 13Y indicated by the arrow are an eraser lamp 181 made up of an LED, a toner recovery screw 182, a cleaning blade 183, a charging device 18Y, and a developing device 11Y. Note that the exposure device arranged between the charging device 18Y and the developing device 11Y is omitted.

[0046] An eraser lamp 181 irradiates the surface of the photoreceptor 13Y to eliminate static electricity before charging, a cleaning blade 183 removes residual toner from the surface of the photoreceptor 13Y, and a toner recovery screw 182 recovers the removed residual toner.

[0047] The charging device 18Y includes a charging roller 184 and a cleaning roller 185. During image formation, a voltage of a predetermined polarity is applied to the charging roller 184 to charge the photoconductor 13Y, and the charging roller 184 is in contact with the photoconductor 13Y not only during image formation but also when image formation is stopped. The cleaning roller 185 cleans the surface of the charging roller 184.

[0048] The developing device 11Y includes a toner height regulating plate 111 that regulates the amount of toner adhesion, a developing roller 115, a toner stirring screw 113 that stirs the toner while transporting it, a toner supply screw 114 that transports and supplies the stirred toner to the developing roller 115, and a toner concentration sensor 112 called a TCR sensor.

[0049] During image formation, the developing roller 115 is applied with a voltage of a predetermined polarity, which supplies toner to the charged and exposed photoreceptor 13Y, forming a visible toner image on the surface of the photoreceptor 13Y. The developing roller 115 is in contact with the photoreceptor 13Y not only during image formation but also when image formation is stopped.

[0050] The toner image formed on the photosensitive member 13Y is primarily transferred onto the intermediate transfer belt 14 by the primary transfer roller 17Y to which a predetermined voltage is applied. The primary transfer roller 17Y is in contact with the intermediate transfer belt 14 both during image formation and when image formation is stopped.

[0051] Next, an application unit that applies a secondary transfer voltage (also called a secondary transfer output) to the secondary transfer roller 19 will be described with reference to FIG.

[0052] In this embodiment, a voltage (also called a static elimination output) is also applied to the static elimination needle 192, but a transformer that generates both the static elimination output and a negative secondary transfer output is used.

[0053] 4, reference numeral 200 denotes an application unit, which has a neutralization transformer (corresponding to a second voltage generating means) 201, which also serves as a secondary transfer (-) transformer. The neutralization output from the neutralization transformer 201 is applied to the neutralization needle 192.

[0054] Reference numeral 202 denotes a secondary transfer (+) transformer (corresponding to a first voltage generating means), which is connected to the neutralization transformer 201. A secondary transfer output output from the secondary transfer (+) transformer 202 is applied to the secondary transfer roller 19. This secondary transfer output is a voltage obtained by adding together the voltage output from the neutralization transformer 201 and the voltage output from the secondary transfer (+) transformer 202.

[0055] For example, when the output of the neutralization transformer 201 is −3000 V and the output of the secondary transfer (+) transformer 202 is +1000 V, the secondary transfer output is −2000 V, which is the sum of both voltages. Also, when the output of the neutralization transformer 201 is −1000 V and the output of the secondary transfer (+) transformer 202 is +3000 V, the secondary transfer output is +2000 V, which is the sum of both voltages. The output voltages of the neutralization transformer 201 and the secondary transfer (+) transformer 202 can be changed by changing the duty ratio of a PWM (pulse width modulation) signal, which is a control signal. The PWM signal is changed based on a command from the control unit 51.

[0056] FIG. 5 is a sequence diagram showing an example of the transition of the secondary transfer output applied to the secondary transfer roller 19 and the static elimination output applied to the static elimination needle 192. In FIG.

[0057] During image formation (printing), a positively charged secondary transfer output (print output) is applied to the secondary transfer roller 19, and after printing is completed, a cleaning sequence is initiated after a specified period of stop mode. During cleaning, a negative charge is output, and then the output is turned off, and during standby, the voltage becomes 0V.

[0058] On the other hand, regarding the neutralization output, a negative charge is output during printing, and after a predetermined period of stop mode when printing is completed, a cleaning sequence is entered, and a negative charge with a different value than during printing is output during cleaning, after which the output is turned off and becomes 0V during standby.

[0059] Previously, during standby, the output of the neutralization transformer was set to -200V, the output of the secondary transfer (+) transformer was set to +200V, and the secondary transfer output was controlled so that the sum of these was ±0V.

[0060] However, there are cases where the secondary transfer output does not become 0 V but ends up outputting several volts due to variations in the circuit components. In this case, in a configuration where the secondary transfer roller 19 and the intermediate transfer belt 14 are constantly in pressure contact as in this embodiment, the output of several volts continues to be applied to the secondary transfer roller 19, causing a transfer memory on the intermediate transfer belt 14, and at the next printing time, the image does not appear in the transfer memory area, causing white spots and resulting in a defective image.

[0061] FIG. 6 is a graph showing the output characteristics of the secondary transfer (+) transformer, and FIG. 7 is a graph showing the output characteristics of the neutralization transformer.

[0062] In both graphs, the horizontal axis represents the duty ratio (PWM [%]) of the PWM signal, which is the control signal, and the vertical axis represents the output voltage. In both transformers 201 and 202, the output voltage switches according to the duty ratio of the PWM signal.

[0063] The PWM signal of the neutralization transformer 201 also serves as a remote signal for controlling the on / off of the output, and is set so that the output is turned off when the duty ratio is 0%.

[0064] In this embodiment, as a countermeasure to the problem that the secondary transfer output is several volts during standby due to circuit variations and transfer memory occurs on the intermediate transfer belt 14, the PWM signal that is the control signal for the neutralizing transformer 201 is set to output off (duty ratio 0%), turning off the neutralizing transformer 201, and the PWM signal that is the output control signal for the secondary transfer (+) transformer 202 is set to a negative output as shown by the dashed rectangle in Fig. 6. In reality, because the neutralizing transformer 201 is off, even if the output of the secondary transfer (+) transformer 202 is set to a negative output, the secondary transfer output is not a negative output, making it possible to ensure the desired 0V.

[0065] In this embodiment, while the image forming apparatus 1 is on standby, the application unit 200 applies a voltage of negative polarity (corresponding to the second polarity) different from the positive polarity (corresponding to the first polarity) during image formation to the secondary transfer roller 19 that contacts the intermediate transfer belt 14. This reliably prevents a slight voltage of the first polarity, which is the same as that during image formation, from being applied to the secondary transfer roller 19 during standby, thereby preventing image defects due to transfer memory.

[0066] Furthermore, there is no need to provide a mechanism for separating the secondary transfer roller 19 and the intermediate transfer belt 14 during standby, or a switching circuit for setting the secondary transfer voltage to zero volts, so there is no increase in costs due to a complicated configuration.

[0067] When restarting the application of voltage to the secondary transfer roller 19, it is advisable to change the duty ratio of the PWM signal, which is a control signal, to start outputting the neutralization transformer 201, which generates a negative voltage, before generating a positive voltage using the secondary transfer (+) transformer 202.

[0068] In the above embodiment, a case has been described in which a negative voltage, different from the positive voltage during image formation, is applied during standby after image formation, but such voltage application may be performed when image formation by the image forming apparatus 1 is stopped. The case in which image formation is stopped includes at least any of the following, in addition to when the image forming apparatus 1 is on standby as in the embodiment, when it is in energy saving mode, when it is in service mode, when it is in cleaning mode before printing starts or when it finishes, when it is stopped due to a machine abnormality, etc.

[0069] Furthermore, the period during which a positive voltage is applied to the secondary transfer roller 19 during image formation may be during a printing operation, a stabilization operation, or an image patch printing, and includes at least one of these.

[0070] In addition, in the above embodiment, the first rotating member is the secondary transfer roller 19, the second rotating member is the intermediate transfer belt 14, and when image formation is stopped, it is possible to prevent a slight voltage of the first polarity, which is the same as that during image formation, from being applied to the secondary transfer roller 19, thereby preventing the occurrence of image defects caused thereby.

[0071] However, the first rotating member and the second rotating member are not limited to the secondary transfer roller 19 and the intermediate transfer belt 14, but can also be applied between two rotating members in which a predetermined voltage is applied to the first rotating member during image formation and the first rotating member and the second rotating member are in contact when image formation is stopped.

[0072] For example, the first rotating member may be primary transfer rollers 17Y, 17M, 17C, and 17K, and the second rotating member may be intermediate transfer belt 14. In this case, when image formation is stopped, by applying a voltage of a different polarity to that used during normal image formation to primary transfer rollers 17Y, 17M, 17C, and 17K, it is possible to reliably prevent a slight voltage of the same polarity as that used during image formation from being applied to the intermediate transfer belt when image formation is stopped, thereby preventing image defects.

[0073] Alternatively, the first rotating member may be the charging roller 184, and the second rotating member may be the photosensitive members 13Y, 13M, 13C, and 13K. In this case, by applying a voltage of a different polarity to the charging roller 184 when image formation is stopped, it is possible to reliably prevent a slight voltage of the same polarity as that used during image formation from being applied to the photosensitive member when image formation is stopped, thereby preventing image defects.

[0074] Alternatively, the first rotating member may be the developing roller 115, and the second rotating member may be the photoconductors 13Y, 13M, 13C, and 13K. In this case, by applying a voltage of a different polarity to that used during normal image formation to the developing roller 115 when image formation is stopped, it is possible to reliably prevent a slight voltage of the same polarity as that used during image formation from being applied to the photoconductors 13Y, 13M, 13C, and 13K when image formation is stopped, thereby preventing image defects. [Explanation of symbols]

[0075] 1. Image forming device 10 Image forming unit 11Y,11M,11C,11K developing device 12Y, 12M, 12C, 12K photoconductor unit 13Y,13M,13C,13K photoreceptor 14 Intermediate transfer belt 17Y, 17M, 17C, 17K Primary transfer roller 18Y, 18M, 18C, 18K charging device 19 Secondary transfer roller 115 Developing roller 184 Charging roller 192 Anti-static needle 200 Applicator 201 Static elimination transformer 202 Secondary transfer (+) transformer

Claims

1. a first rotating member; a second rotating member that contacts the first rotating member when image formation is stopped; a first voltage generating means capable of generating a voltage of a first polarity and a voltage of a second polarity; a second voltage generating means capable of generating a voltage of a second polarity; an application means for applying a voltage of the first polarity generated by adding together a voltage of the first polarity generated by the first voltage generation means and a voltage of the second polarity generated by the second voltage generation means to the first rotating member during image formation, and for stopping the output of the voltage of the second polarity by the second voltage generation means, setting the first voltage generation means to output a voltage of the second polarity, and applying the output voltage of the second polarity to the first rotating member when the image formation is stopped; An image forming apparatus comprising:

2. 2. The image forming apparatus according to claim 1, wherein the first rotating member is a secondary transfer roller, and the second rotating member is an intermediate transfer belt.

3. 2. The image forming apparatus according to claim 1, wherein the first rotating member is a primary transfer roller, and the second rotating member is an intermediate transfer belt.

4. 2. The image forming apparatus according to claim 1, wherein the first rotating member is a charging roller, and the second rotating member is a photosensitive member.

5. 2. The image forming apparatus according to claim 1, wherein the first rotating member is a developing roller, and the second rotating member is a photosensitive member.

6. 6. The image forming apparatus according to claim 1, wherein the image forming state includes at least one of a printing operation, a stabilization operation, and an image patch printing operation.

7. The image forming apparatus according to any one of claims 1 to 6, wherein the state in which image formation is stopped includes at least one of the following states: when the image forming apparatus is in standby mode, in energy saving mode, in service mode, in cleaning mode before printing starts or at the end of printing, and when stopped due to a machine abnormality.

8. 8. The image forming apparatus according to claim 1, wherein the applying means applies the voltage of the second polarity generated by the second voltage generating means to another member different from the first rotating member.

9. An image forming apparatus according to any one of claims 1 to 8, wherein when the application of the voltage of the first polarity to the first rotating member is stopped, the application means waits for a predetermined time to elapse after transitioning to a predetermined stop mode and then stops output.

10. An image forming apparatus according to any one of claims 1 to 9, wherein when the application of the voltage of the first polarity to the first rotating member is resumed, the application means starts outputting the second voltage generating means that generates the voltage of the second polarity, and then generates the voltage of the first polarity by the first voltage generating means.

11. a first rotating member; a second rotating member that contacts the first rotating member when image formation is stopped; a first voltage generating means capable of generating a voltage of a first polarity and a voltage of a second polarity; a second voltage generating means capable of generating a voltage of a second polarity; An image forming apparatus comprising: a voltage application step of applying a voltage of a first polarity generated by adding together a voltage of the first polarity generated by the first voltage generation means and a voltage of the second polarity generated by the second voltage generation means to the first rotating member during image formation, and when the image formation is stopped, stopping the output of the voltage of the second polarity by the second voltage generation means, setting the first voltage generation means to output a voltage of the second polarity, and applying the output voltage of the second polarity to the first rotating member.

12. a first rotating member; a second rotating member that contacts the first rotating member when image formation is stopped; a first voltage generating means capable of generating a voltage of a first polarity and a voltage of a second polarity; a second voltage generating means capable of generating a voltage of a second polarity; A computer of an image forming apparatus including: A program for executing an application step of applying, to the first rotating member during image formation, a voltage of the first polarity generated by the first voltage generating means and a voltage of the second polarity generated by the second voltage generating means, and, when the image formation is stopped, stopping the output of the voltage of the second polarity by the second voltage generating means, setting the first voltage generating means to output the voltage of the second polarity, and applying the output voltage of the second polarity to the first rotating member.

Images