JP2008203763A - Image-forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image-forming device in which it is precisely determined whether or not a transfer belt is broken. <P>SOLUTION: A voltage detection part 74 detects voltage values between a photoreceptor drum 12 and a primary transfer roll 24 in a state in which an intermediate transfer drum 22 is put between the photoreceptor drum 12 and the primary transfer roll 24. An average value computation part 98 computes an average value of the voltage values. A proportion computation part 100 computes proportions of variations in the voltage values to the average value computed by the average value computation part 98. A breakage determination part 102 compares the proportions computed by the proportion computation part 100 with a threshold value, and determines that the intermediate belt 22 is broken in case that a period in which the proportions exceed the threshold value continues for a prescribed period of time. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image forming apparatus.

  A toner image is formed on an image carrier such as a photosensitive drum, the toner image on the image carrier is transferred to a transfer belt, and then the toner image on the transfer belt is transferred to a recording sheet to form an image. An image forming apparatus to perform is known.

  By the way, in this type of image forming apparatus, the transfer belt may be damaged due to the use state of the transfer belt, the frequency of use, the installation environment of the image forming apparatus, deterioration with time, and the like.

For this reason, Patent Document 1 discloses an image forming apparatus configured to transfer a toner image on a photosensitive drum to the transfer belt by sandwiching the transfer belt between the photosensitive drum and a transfer roll. A predetermined voltage is applied between the transfer roll, the current value of the current flowing between the photosensitive drum and the transfer roll is detected, and the transfer belt is damaged when the current value exceeds a predetermined level. A technique for determining that a device is present is disclosed.
Japanese Patent Laid-Open No. 11-15290

  The present invention has been made in the above technical background, and an object of the present invention is to provide an image forming apparatus capable of accurately determining whether or not a transfer belt is damaged.

  In order to achieve the above object, an image forming apparatus according to claim 1, an image holding body that holds a toner image, a transfer belt to which the toner image held on the image holding body is transferred, and the image A transfer means for transferring the toner image to the transfer belt with the transfer belt sandwiched between the holding body, and the image holding body and the transfer means with the transfer belt sandwiched between the image holding body and the transfer means; Detecting means for detecting a resistance value between, and determining whether or not a period during which the fluctuation range of the resistance value detected by the detecting means exceeds a predetermined threshold is a predetermined period or more, A damage determining means for determining that the transfer belt is damaged when it is determined that the time is equal to or longer than a predetermined period.

  According to a second aspect of the present invention, in the first aspect of the present invention, when the transfer belt is driven and the damage determination means determines that the transfer belt is damaged. And a drive stop means for stopping the drive of the transfer belt.

  According to a third aspect of the present invention, in the first or second aspect of the invention, the transfer belt is damaged when the breakage determining means determines that the transfer belt is damaged. Informing means for informing that the user is present is further provided.

  The invention according to claim 4 is the invention according to any one of claims 1 to 3, wherein the transfer means is made of metal.

  According to a fifth aspect of the present invention, in the invention according to any one of the first to fourth aspects, the image carrier rotates when the toner image is transferred onto the transfer belt, and When the resistance value periodically fluctuates, the breakage determination means is the case where the frequency of the resistance value fluctuation exceeds the number of rotations per second of the image carrier, and the period is When it is determined that it is longer than the predetermined period, it is determined that the transfer belt is damaged.

  The invention according to claim 6 is the invention according to any one of claims 1 to 5, wherein the fluctuation range is a value normalized by an average value of the resistance values. It is a feature.

  The invention according to claim 7 is the invention according to any one of claims 1 to 6, wherein the detection means indicates the resistance value, and the image holding body and the transfer means. And a voltage value or current between the image carrier and the transfer unit when a known amount of power is applied between the image carrier and the transfer unit with the transfer belt sandwiched therebetween. The value is detected.

  According to the first aspect of the present invention, it is possible to determine whether or not the transfer belt is damaged with higher accuracy than when the present invention is not applied.

  According to the second aspect of the present invention, when the transfer belt is damaged, it is possible to prevent the occurrence of a problem associated with the damage, as compared with the case where the present invention is not applied. An effect is obtained.

  According to the third aspect of the invention, there is an effect that the user can easily grasp that the transfer belt is damaged.

  According to the fourth aspect of the present invention, the difference between the fluctuation range of the resistance value when the transfer belt is not damaged and the fluctuation range of the resistance value when the transfer belt is damaged is made significant. As a result, it is possible to determine whether or not the transfer belt is damaged more accurately than when the present invention is not applied.

  According to the fifth aspect of the present invention, compared to the case where the present invention is not applied, noise due to rotation of the image carrier is erroneously determined as a change in resistance value when the transfer belt is damaged. The effect that it can be avoided is obtained.

  According to the sixth aspect of the present invention, as a result of being able to reduce the threshold value to one, it is possible to minimize the storage capacity required for storing the threshold value in storage means such as a semiconductor memory. The effect of being able to be obtained is obtained.

  Further, according to the invention described in claim 7, it is possible to obtain an effect that the present invention can be easily realized as compared with the case where the present invention is not applied.

  The best mode for carrying out the present invention will be described below in detail with reference to the drawings.

[First embodiment]
FIG. 1 shows a configuration example of an image forming apparatus 10 to which the present invention is applied. As shown in the figure, a photosensitive drum 12 as an image holding member is rotatably disposed inside an image forming apparatus 10 according to the present embodiment. The photosensitive drum 12 has a grounded metal shaft 13 covered with a resin photosensitive layer, and the driving force of a driving means such as a motor (not shown) is transmitted to the metal shaft 13 so that the direction of the arrow is indicated. Is driven to rotate. The surface of the photosensitive drum 12 is charged to a predetermined potential by a charging roll 14 disposed almost directly below the photosensitive drum 12, and then an exposure device disposed at a position approximately directly below the charging roll 14. 16, the laser beam (LB) is exposed (see the broken line arrow in FIG. 1), and an electrostatic latent image corresponding to the image information is formed. The electrostatic latent image formed on the photoconductive drum 12 passes through the developing units 18Y, 18M, 18C, and 18K of the respective colors Y (yellow), M (magenta), C (cyan), and K (black) in the circumferential direction. The toner is developed by a rotary developing device 20 disposed along the toner image, and becomes a toner image of a predetermined color.

  At this time, charging, exposure, and development processes are repeated a predetermined number of times on the surface of the photosensitive drum 12 in accordance with the color of the image to be formed. The developing device 20 moves the corresponding color developing devices 18Y, 18M, 18C, and 18K to a developing region facing the photosensitive drum 12. For example, when a full-color image is formed, charging, exposure, and development processes are repeated four times on the surface of the photosensitive drum 12 corresponding to each color of Y, M, C, and K, and the photosensitive drum. A toner image corresponding to each color of Y, M, C, and K is sequentially formed on the surface 12.

  A resin intermediate transfer belt 22 is stretched around the outer periphery of the photosensitive drum 12 so as to be in lap contact, and is a primary transfer serving as a transfer unit at a position in contact with the photosensitive drum 12 via the intermediate transfer belt 22. A roll 24 is arranged. The primary transfer roll 24 is made of metal and is biased toward the center of the photosensitive drum 12 by a biasing means such as a coil spring (not shown).

  The toner images of the respective colors Y, M, C, and K that are sequentially formed on the photosensitive drum 12 are primarily transferred by the action of the primary transfer roll 24 at the primary transfer position where the intermediate transfer belt 22 is in lap contact with the intermediate transfer belt 22. Each color toner image is superimposed on the belt 22. The Y, M, C, and K toner images transferred onto the intermediate transfer belt 22 are transferred onto the recording paper P as a transfer material fed at a predetermined timing. The secondary transfer is performed at once. The recording paper P is fed from a paper feed cassette 28 arranged at the lower part of the image forming apparatus 10 in a state where it is fed one by one by a feed roll 30 and a retard roll 32, and is conveyed by a conveyance roll 34. Then, the recording paper P is conveyed to the secondary transfer position of the intermediate transfer belt 22 in a state of being synchronized with the toner image transferred onto the intermediate transfer belt 22 by the registration roll 36.

  A wrap-in roll 38 that specifies the wrap position of the intermediate transfer belt 22 on the upstream side in the rotation direction of the photosensitive drum 12, a primary transfer roll 24, and a lap that specifies the wrap position of the intermediate transfer belt 22 on the downstream side of the wrap position. Out roll 40, tension rolls 42 and 46, backup roll 44 in contact with secondary transfer roll 26 via intermediate transfer belt 22, and residual toner for attaching residual toner on intermediate transfer belt 22 to photosensitive drum 12 The intermediate transfer belt 22 is stretched with a predetermined tension on the backup roll 50 facing the charge applying roll 48 for residual toner that applies charge to the toner. The intermediate transfer belt 22 is driven as the photosensitive drum 12 rotates.

  The recording paper P onto which the toner image is transferred from the intermediate transfer belt 22 is conveyed to the fixing device 52, and the toner image is fixed on the recording paper P by heat and pressure by the fixing device 52, and image formation is performed by the discharge roll 54. It is discharged as it is to a discharge section 56 provided at the upper part of the apparatus 10.

  The residual toner on the intermediate transfer belt 22 after the secondary transfer process of the toner image is attached to the photosensitive drum 12 at the primary transfer position every time the photosensitive drum 12 makes one rotation, and the photosensitive drum 12. Is removed by the cleaning blade 60 of the cleaning device 58 disposed diagonally to the right of the image and prepared for the next image forming step. The toner removed by the cleaning blade 60 is stored in a waste toner container 62 of the cleaning device 58.

  FIG. 2 shows a main configuration of the image forming apparatus 10. As shown in the figure, a primary transfer roll power source 70 is connected to the primary transfer roll 24. A primary transfer roll power supply control unit 72 is connected to the primary transfer roll power supply 70. The primary transfer roll power supply controller 72 controls the primary transfer roll power supply 70 so that predetermined power is applied to the primary transfer roll 24. Note that the primary transfer roll power control unit 72 according to the present embodiment performs constant current control so that a constant current continuously flows through the primary transfer roll 24 for a predetermined period.

  In addition, the image forming apparatus 10 includes a voltage detection unit 74 as a detection unit. The voltage detector 74 is electrically connected to the metal shaft of the primary transfer roll 24 and is also electrically connected to the metal shaft 13 of the photosensitive drum 12. Accordingly, the voltage detection unit 74 can detect a potential difference between the photosensitive drum 12 and the primary transfer roll 24 with the intermediate transfer belt 22 sandwiched between the photosensitive drum 12 and the primary transfer roll 24. Become.

  Next, with reference to FIG. 3, the main configuration of the electrical system of the image forming apparatus 10 will be described.

  As shown in the figure, the image forming apparatus 10 includes a CPU (central processing unit) 76, a ROM (Read Only), in addition to the above-described primary transfer roll power supply 70, primary transfer roll power supply control unit 72, and voltage detection unit 74. Memory (RAM) 78, RAM (Random Access Memory) 80, UI (user interface) panel 82 as notification means, communication interface 84, drive system control unit 86, exposure device control unit 88, charging device control unit 90, developing device control And a fixing device controller 94.

  The CPU 76 controls the overall operation of the image forming apparatus 10. The ROM 78 stores in advance a control program for controlling the operation of the image forming apparatus 10, a damage determination processing program described later, various data, and the like. The RAM 80 is used as a work area or the like when executing various programs.

  The UI panel 82 is composed of a touch panel display or the like in which a transmissive touch panel is superimposed on a display. Various types of information are displayed on the display surface of the display, and desired information and instructions are input when the user touches the touch panel. Is done.

  The communication interface 84 is connected to a terminal 96 such as an external personal computer and receives various information such as image information indicating an image formed on the recording paper P from the terminal 96.

  The drive system control unit 86 performs drive system control such as control of conveyance of the recording paper P and control of drive of the photosensitive drum 12 and the intermediate transfer belt 22, and this control is performed by the conveyance roll 34 and the photoconductor. This is realized by controlling the driving of a driving means (not shown) that applies a driving force to the drum 12 or the like.

  The exposure apparatus control unit 88 is connected to an exposure apparatus power source (not shown), and controls power supplied to the exposure apparatus 16 to output a laser beam.

  The charging device controller 90 is connected to a charging device power source (not shown), and controls the power supplied to the charging roll 14 and the residual toner charge applying roll 48.

  The developing device control unit 92 is connected to a toner cartridge (not shown), and controls the amount of toner supplied by operating the toner cartridge when supplying toner into each developing device. The developing device control unit 92 is connected to a developing device power supply (not shown) and controls the power supplied to the developing device 20. The fixing device control unit 94 controls the operation of the fixing device 52.

  Primary transfer roll power supply controller 72, voltage detector 74, CPU 76, ROM 78, RAM 80, UI panel 82, communication interface 84, drive system controller 86, exposure device controller 88, charging device controller 90, developing device controller 92 and the fixing device controller 94 are electrically connected to each other via a system bus BUS.

  Accordingly, the CPU 76 controls access to the ROM 78 and the RAM 80, exchanges various information with the terminal 96 via the communication interface 84, controls exchange of various information with the UI panel 82, and power supply control for the primary transfer roll. Control of each part of the unit 72, voltage detection unit 74, drive system control unit 86, exposure device control unit 88, charging device control unit 90, developing device control unit 92, and fixing device control unit 94. Can do.

  FIG. 4 is a functional block diagram showing a functional configuration of the CPU 76. As shown in the figure, the CPU 76 includes an average value calculation unit 98, a ratio calculation unit 100, and a damage determination unit 102. The CPU 76 includes a timer (not shown) that starts and resets the timing.

  The voltage detection unit 74 detects a voltage value indicating a potential difference between the photosensitive drum 12 and the primary transfer roll 24, converts the voltage value into a digital value, and outputs the digital value to the average value calculation unit 98 and the ratio calculation unit 100. To do.

  The average value calculation unit 98 acquires a voltage value for a predetermined period (in this embodiment, the time required for one rotation of the photosensitive drum 12) from the voltage detection unit 74, and calculates the average value of the voltage values. To do. Then, the average value is output to the ratio calculation unit 100.

  The ratio calculation unit 100 first acquires the same voltage value as that acquired by the average value calculation unit 98 from the voltage detection unit 74 from the voltage detection unit 74, and calculates the fluctuation range of the voltage value. Then, a ratio of the fluctuation range of the voltage value to the average value input from the average value calculation unit 98 (a value obtained by dividing the fluctuation range of the voltage value by the average value input from the average value calculation unit 98) is calculated. Is output to the damage determination unit 102. In the present embodiment, an example is described in which the average value calculation unit 98 and the ratio calculation unit 100 acquire voltage values for the time required for one rotation of the photosensitive drum 12 from the voltage detection unit 74. However, what amount of voltage value is to be acquired may be determined in consideration of the design specifications and cost of the image forming apparatus 10.

  When the ratio calculated by the ratio calculation unit 100 is input, the damage determination unit 102 reads a threshold value stored in advance in the ROM 78 and compares the ratio with the threshold value. If the ratio does not exceed the threshold value, it is determined that the intermediate transfer belt 22 is not damaged. On the other hand, when the ratio exceeds the threshold value, the timer (not shown) is reset and time measurement is started. Whenever the ratio is input from the ratio calculation unit 100, the damage determination unit 102 compares the ratio with a threshold value. If the period in which the ratio exceeds the threshold value continues for a predetermined period, the intermediate transfer belt 22 On the other hand, if it is determined that the intermediate transfer belt 22 is not damaged, if the period in which the ratio exceeds the threshold value does not continue for a predetermined period, it is determined that the intermediate transfer belt 22 is not damaged.

  In addition, when the damage determination unit 102 determines that the intermediate transfer belt 22 is damaged, the damage determination unit 102 displays a message indicating that the intermediate transfer belt 22 is damaged on the UI panel 82.

  Further, when the damage determination unit 102 determines that the intermediate transfer belt 22 is damaged, the damage determination unit 102 outputs a drive stop signal indicating that the drive of the photosensitive drum 12 is stopped to the drive system control unit 86. In response to this, the drive system controller 86 stops the drive of the drive means. As a result, the driving of the photosensitive drum 12 is stopped, and accordingly, the driving of the intermediate transfer belt 22 driven by the photosensitive drum 12 is also stopped.

  The threshold value is a value at which the intermediate transfer belt 22 is determined to be damaged when the ratio exceeds this value. In the present embodiment, a test using an actual apparatus of the image forming apparatus 10 or an image forming apparatus is used. Values obtained in advance by computer simulation or the like based on 10 design specifications are applied.

  Here, the principle of a method for determining whether or not the intermediate transfer belt 22 is damaged in the image forming apparatus 10 according to the present embodiment will be described.

  In FIG. 5, when the intermediate transfer belt 22 in a normal state (there is no damaged portion) is sandwiched between the photosensitive drum 12 and the primary transfer roll 24, the photosensitive drum 12 is electrostatically latent. After charging to a state where an image can be formed, voltage detection is performed when a current of 10 μA is continuously supplied to the primary transfer roll 24 for a predetermined time while the photosensitive drum 12 and the intermediate transfer belt 22 are driven at a predetermined speed. The graph which shows an example of the relationship between the voltage value detected by the part 74 and time is shown. As shown in the figure, the fluctuation range of the voltage value during one rotation of the photosensitive drum 12 is about 90V, and the average value of the voltage value is about 1120V. Accordingly, the ratio of the fluctuation range of the voltage value to the average value in this case is about 0.08 (≈90 ÷ 1120).

  On the other hand, in FIG. 6, when the intermediate transfer belt 22 is damaged, the voltage value and time detected by the voltage detection unit 74 under the same conditions as in the normal state of the intermediate transfer belt 22 described above. A graph showing an example of the relationship is shown. As shown in the figure, the fluctuation range of the voltage value during one rotation of the photosensitive drum 12 is about 700V, and the average value of the voltage value is about 800V. Accordingly, the ratio of the fluctuation range of the voltage value to the average value in this case is about 0.88 (≈700 / 800).

  Here, for example, when the threshold value is set to 0.5, the damage determination unit 102 does not damage the intermediate transfer belt 22 because about 0.08 obtained from the graph shown in FIG. 5 does not exceed the threshold value. Judge. On the other hand, the damage determination unit 102 determines that an intermediate value is obtained when about 0.88 obtained from the graph shown in FIG. 6 exceeds the threshold value and this state continues for a predetermined period (for example, while the photosensitive drum rotates 5 times). It is determined that the transfer belt 22 is damaged.

  By the way, the present inventors adopted a metal roll instead of a roll in which a metal shaft is covered with rubber as in the prior art as a primary transfer roll, and the voltage value detected by the voltage detector 74 is the primary transfer roll. It was found that it vibrates according to the vibration of the roll. Therefore, in the present embodiment, the primary transfer roll 24 is made of metal. As a result, compared to the case of using a conventional primary transfer roll, that is, a primary transfer roll in which a metal shaft is covered with rubber, the fluctuation range of the voltage value when the intermediate transfer belt 22 is not damaged and the intermediate transfer belt 22 are damaged. Thus, the difference from the fluctuation range of the voltage value can be made remarkable.

  By the way, the process by each component of CPU76 comprised as shown in FIG. 4 can be implement | achieved by a software structure using a computer by running a program. However, the present invention is not limited to realization by a software configuration, and needless to say, it can also be realized by a hardware configuration or a combination of a hardware configuration and a software configuration.

  Hereinafter, a description will be given of a case where the image forming apparatus 10 according to the present embodiment realizes processing by each of the above-described components by executing the above-described program (hereinafter referred to as “damage determination processing program”). To do. In this case, the damage determination processing program is installed in the image forming apparatus 10 in advance, provided in a state stored in a computer-readable recording medium, or distributed via wired or wireless communication means. The form etc. which can be applied are applicable.

  Next, with reference to FIG. 7, the operation of the image forming apparatus 10 when executing the damage determination processing program will be described. 7 shows the processing of the damage determination processing program executed by the CPU 76 when information instructing whether or not the intermediate transfer belt 22 is damaged is input from the UI panel 82 or the terminal 96. It is a flowchart showing the flow, and the program is stored in the ROM 78 in advance.

  In step 200 of the figure, the charging device controller 90 is controlled so as to charge the photosensitive drum 12 to a state where an electrostatic latent image can be formed, and the driving system is started so as to start driving the intermediate transfer belt 22. The controller 86 is controlled, and in the next step 202, the primary transfer roll power supply controller 72 is controlled so as to start application of predetermined power to the primary transfer roll 24, and then in the next step 204, the voltage detector Acquisition of the voltage value from 74 is started.

  In the next step 206, the voltage value for the predetermined period is acquired and the average value of the voltage value is calculated in the same manner as the processing of the average value calculation unit 98 described above. Similar to the processing of the ratio calculation unit 100, after obtaining the voltage value for the predetermined period and calculating the fluctuation range of the voltage value, the ratio of the fluctuation range of the voltage value to the average value calculated in step 206 is calculated. calculate.

  In the next step 210, it is determined whether or not the ratio calculated in step 208 exceeds a predetermined threshold in the same manner as the processing of the damage determination unit 102 described above. Here, when a negative determination is made, the process proceeds to step 222 described later, whereas when an affirmative determination is made, the process proceeds to step 212.

  In step 212, the timer is reset after the timer is reset, as in the process of the damage determination unit 102 described above. In step 214, the process of step 208 is performed as in the process of the damage determination unit 102 described above. It is determined whether or not the period during which the ratio calculated in (1) exceeds a predetermined threshold continues for a predetermined period or more. Here, if the determination is affirmative, the intermediate transfer belt 22 is regarded as damaged, and the process proceeds to step 224 described later, whereas if the determination is negative, the process proceeds to step 216.

  In step 216, the average value of the voltage value is calculated in the same manner as the processing of the average value calculation unit 98 described above, and in the next step 218, as in the processing of the ratio calculation unit 100 described above, for the predetermined period. After obtaining the voltage value and calculating the fluctuation range of the voltage value, the ratio of the fluctuation range of the voltage value to the average value calculated in step 216 is calculated.

  In the next step 220, it is determined whether or not the ratio calculated in step 218 exceeds a predetermined threshold as in the processing of the damage determination unit 102 described above. Here, if a negative determination is made, the process proceeds to step 222, whereas if an affirmative determination is made, the process returns to step 214.

  In step 222, it is determined whether or not it is time to end the damage determination processing program. Here, if a negative determination is made, the process returns to step 206. If an affirmative determination is made, the process proceeds to step 226 described later. An example of the timing for ending the above-described damage determination processing program is when the photosensitive drum 12 has rotated a predetermined number of times (for example, 10 times).

  In step 224, damage handling processing is performed. In the present embodiment, a message indicating that the intermediate transfer belt 22 is damaged is displayed on the UI panel 82 as the damage handling process. When the damage handling process ends, the process proceeds to step 226.

  In step 226, the charging device controller 90 is controlled so as to release the charged state of the photosensitive drum 12, and the drive system controller 86 is controlled so as to stop the driving of the intermediate transfer belt 22. Then, after controlling the primary transfer roll power supply control unit 72 so as to stop the application of the predetermined power to the primary transfer roll 24, the acquisition of the voltage value from the voltage detection unit 74 is stopped in the next step 230. When the processing of step 230 is completed, the breakage determination processing program ends.

  In this case, the processing of step 210, step 212, step 214, and step 220 corresponds to the damage determination means of the present invention, and the processing of step 226 corresponds to the drive stop means of the present invention.

[Second Embodiment]
In the second embodiment, an example in which the frequency determination unit 110 is added to the CPU 76 of the first embodiment to form a CPU 76 ′ will be described. The configuration of the image forming apparatus 10 according to the second embodiment is the same as that of the image forming apparatus 10 according to the first embodiment except for the configuration of the CPU. Here, FIG. 8 is referred to. The configuration of the CPU 76 ′ according to the second embodiment will be described. In FIG. 8, the same components as those in FIG. 4 are denoted by the same reference numerals as those in FIG.

  As shown in FIG. 8, the CPU 76 ′ of the second embodiment is different from the CPU 76 of the first embodiment only in that a frequency determination unit 110 is added.

  First, the frequency determination unit 110 obtains a voltage value for a predetermined period (in this embodiment, the time required for one rotation of the photosensitive drum 12) from the voltage detection unit 74, and the frequency of fluctuation of the voltage value. And the number of revolutions per second of the photosensitive drum 12 stored in advance in a built-in memory (not shown) is read out. Next, the frequency of fluctuation of the voltage value is compared with the number of revolutions per second of the photosensitive drum 12, and whether or not the frequency of fluctuation of the voltage value exceeds the number of revolutions per second of the photosensitive drum 12 is determined. to decide. An average value calculation instruction signal indicating that the average value calculation unit 98 is instructed to calculate the average value only when the frequency of the voltage value fluctuation exceeds the number of rotations per second of the photosensitive drum 12. Output.

  That is, as shown in FIG. 9, the frequency determination unit 110 determines the average value when the number of pulse waves indicating the fluctuation of the voltage value within one time α required for one rotation of the photosensitive drum 12 is 1 or less. The average value calculation instruction signal is not output to the calculation unit 98, and as shown in FIG. 10, there are a plurality of pulse waves indicating the fluctuation of the voltage value within the time α required for one rotation of the photosensitive drum 12. In this case, an average value calculation instruction signal is output to the average value calculation unit 98. In FIG. 9, when the intermediate transfer belt is not damaged, the photosensitive drum and the intermediate transfer belt are driven at a predetermined speed after charging the photosensitive drum so that an electrostatic latent image can be formed. However, FIG. 10 is a graph showing how the voltage value detected by the voltage detector 74 changes when a constant current is continuously supplied to the primary transfer roll for a predetermined time. FIG. 10 shows a case where the intermediate transfer belt is damaged. After charging the photosensitive drum to a state where an electrostatic latent image can be formed, a constant current is continuously supplied to the primary transfer roll for a predetermined time while the photosensitive drum and the intermediate transfer belt are driven at a predetermined speed. It is a graph which shows the fluctuation | variation aspect of the voltage value detected by the voltage detection part 74 when doing.

  The average value calculation unit 98 calculates the average value of the voltage values detected by the voltage detection unit 74 as described in the first embodiment in response to the average value calculation instruction signal input from the frequency determination unit 110. I do.

  Note that the processing by each component of the CPU 76 ′ according to the second embodiment configured as described above is also realized by a software configuration using a computer by executing the damage determination processing program of the present invention. can do. However, it is not limited to realization by software configuration, and it goes without saying that it can be realized by hardware configuration or a combination of hardware configuration and software configuration.

  Hereinafter, a case will be described in which the image forming apparatus 10 according to the second exemplary embodiment realizes processing by each of the above-described components by executing the damage determination processing program. In this case, the damage determination processing program is installed in the image forming apparatus 10 in advance, provided in a state stored in a computer-readable recording medium, or distributed via wired or wireless communication means. The form etc. which can be applied are applicable.

  Next, the operation of the image forming apparatus 10 when the damage determination processing program is executed will be described with reference to FIG. FIG. 11 shows the processing of the damage determination processing program executed by the CPU 76 when information for instructing whether or not the intermediate transfer belt 22 is damaged is input from the UI panel 82 or the terminal 96. It is a flowchart showing the flow, and the program is stored in the ROM 78 in advance. Further, steps in FIG. 11 that perform the same processing as in FIG. 7 are denoted by the same reference numerals as in FIG. 7, and description thereof is omitted as much as possible.

  In step 200 in the figure, the charging device control unit 90 is controlled so as to charge the photosensitive drum 12, and the drive system control unit 86 is controlled so as to start driving the intermediate transfer belt 22. Then, after controlling the primary transfer roll power supply control unit 72 so as to start application of predetermined power to the primary transfer roll 24, the acquisition of the voltage value from the voltage detection unit 74 is started in the next step 204.

  In step 205, similarly to the processing of the frequency determination unit 110 described above, the voltage value for the predetermined period is acquired, the frequency of fluctuation of the voltage value is calculated, and the frequency and the photosensitive drum 12 per second are calculated. The rotational speed is compared, and it is determined whether or not the frequency of fluctuation of the voltage value exceeds the rotational speed per second of the photosensitive drum 12. Here, when the determination is affirmative, the processing of steps 206 to 230 described in the first embodiment is executed, whereas when the determination is negative, the processing proceeds to step 222.

  In step 222, it is determined whether or not it is time to end the damage determination processing program. If a negative determination is made here, the process returns to step 205, whereas if an affirmative determination is made, the process proceeds to step 226. Then, when the process of step 230 ends, the breakage determination processing program ends.

  In this case, the processing of step 205, step 210, step 212, step 214, and step 220 corresponds to the damage determination means of the present invention.

  In the second embodiment, the example in which the frequency of fluctuation of the voltage value is compared with the number of rotations per second of the photosensitive drum 12 has been described. However, the present invention is not limited to this. Alternatively, the frequency of the fluctuation of the voltage value may be compared with a value obtained by multiplying the rotational speed per second of the photosensitive drum 12 by a value larger than 1.

  As mentioned above, although this invention was demonstrated using said each embodiment, the technical scope of this invention is not limited to the range as described in each said embodiment. Various modifications or improvements can be added to the above-described embodiments without departing from the spirit of the invention, and embodiments to which the modifications or improvements are added are also included in the technical scope of the present invention.

  In addition, each of the above embodiments does not limit the invention described in the claims, and all combinations of features described in each of the above embodiments are indispensable for solving means of the invention. Not always. Each of the above embodiments includes inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent elements. Even if some constituent elements are deleted from all the constituent elements shown in each of the above embodiments, as long as an effect is obtained, a configuration in which these some constituent elements are deleted can be extracted as an invention.

  For example, in each of the embodiments described above, the case where the damage determination process is realized by a software configuration has been described. However, the present invention is not limited to this, for example, the form in which the damage determination process is realized by a hardware configuration You can also As an example of the form in this case, for example, a form in which a functional device that executes the same process as each component of the CPU 76 shown in FIG. 4 and the CPU 76 ′ shown in FIG. 8 is created and used can be exemplified. In this case, the breakage determination process can be expected to be faster than in the above embodiments.

  The configuration of the image forming apparatus 10 described in the above embodiments (see FIGS. 1 to 4 and 8) is merely an example, and it is needless to say that the configuration can be appropriately changed without departing from the gist of the present invention. .

  Further, the processing flow (see FIGS. 7 and 11) of the damage determination processing program described in each of the above embodiments is also an example, and unnecessary steps can be deleted or new within the scope of the gist of the present invention. It goes without saying that steps can be added and the processing order can be changed, and can be changed as appropriate. For example, in each of the above embodiments, the process of step 208 is executed in FIGS. 7 and 11, but the present invention is not limited to this, and the step 208 may be deleted in FIGS. good. In this case, a plurality of threshold values different from each other corresponding to the average value calculated in step 206 are stored in advance in storage means such as the ROM 78 or the built-in memory of the CPUs 76 and 76 ', and the average value calculated in step 206 is stored. Is read from the storage means. 7 and FIG. 11, the process of comparing the threshold value with the fluctuation range of the voltage value is executed in step 210 and step 220, and the fluctuation range of the voltage value exceeds the threshold value in step 214. A process for determining whether or not the period continues for a predetermined period or longer is executed. In this case, the same effects as those of the above embodiments can be obtained.

  In each of the above embodiments, the constant current control is performed and the voltage detection unit 74 detects the voltage value. However, the present invention is not limited to this, and the constant voltage control is performed. The current value may be detected. In this case, the same effects as those of the above embodiments can be obtained.

  In each of the above embodiments, an example is described in which constant current control is performed, a voltage value is detected by the voltage detection unit 74, and whether or not the intermediate transfer belt 22 is damaged is determined using the voltage value. However, the present invention is not limited to this, and the resistance value is calculated from the voltage value detected by the voltage detector 74 and the current value in the constant current control, and the intermediate transfer belt 22 is calculated using the resistance value. It may be determined whether or not is damaged. Further, the current value is detected by performing constant voltage control, a resistance value is calculated from the current value and the voltage value in the constant voltage control, and whether or not the intermediate transfer belt 22 is damaged using the resistance value is determined. You may make it judge.

  In this case, the variation range of the resistance value is applied instead of the variation range of the voltage value in each of the above embodiments.

  Further, in each of the above embodiments, the UI panel 82 that displays a message indicating that the intermediate transfer belt 22 is damaged is described as an example of notification means for notifying that the intermediate transfer belt 22 is damaged. However, the present invention is not limited to this. For example, the image forming apparatus 10 may be provided with a speaker, and a sound indicating that the intermediate transfer belt 22 is damaged may be emitted from the speaker. Further, a lamp for notifying that the intermediate transfer belt 22 is damaged may be provided, and the lamp may be turned on or blinked to notify the user that the intermediate transfer belt 22 is damaged. In addition, an external communication device capable of wired communication or wireless communication with the image forming apparatus 10 is equipped with a display panel such as an LCD, a notification unit such as a speaker, a lamp, and the like, and the intermediate transfer belt 22 is configured using the notification unit. You may make it alert | report that it is damaged. Further, any two or more of the UI panel 82, the speaker, the lamp, and the external communication device may be combined to notify that the intermediate transfer belt 22 is damaged. Further, by executing a predetermined instruction input to the UI panel 82, any combination of the UI panel 82, the speaker, the lamp, and the external communication device is used for notification, or no notification is performed at all. May be determined. As the notification means for notifying that the intermediate transfer belt 22 is damaged in this way, the one that is considered to best suit the situation is adopted in consideration of the design specifications, manufacturing cost, user convenience, and the like of the image forming apparatus 10. Just do it.

  In each of the above-described embodiments, the CPU 76 or 76 ′ receives information that instructs the CPU 76 or 76 ′ to determine whether or not the intermediate transfer belt 22 is damaged from the UI panel 82 or the terminal 96. Although an example in which the processing of the damage determination processing program is executed has been described, the present invention is not limited to this. For example, the processing of the damage determination processing program when the main power of the image forming apparatus 10 is turned on. May be executed. Further, when the image information is input from the terminal 96 to the CPUs 76 and 76 ', the processing of the damage determination processing program is executed before the electrostatic latent image is formed on the photosensitive drum 12. In this case, if it is determined that the intermediate transfer belt 22 is damaged, image formation is stopped, and if it is determined that the intermediate transfer belt 22 is not damaged, the photosensitive drum Image formation is executed with the state 12 rotated as it is. Further, the processing of the damage determination processing program may be executed when the processing for forming an image is completed a predetermined number of times. Further, the timing at which the processing of the damage determination processing program is executed may be changed by executing a predetermined instruction input to the UI panel 82. As described above, the timing at which the processing of the damage determination processing program is executed by the CPUs 76 and 76 ′ may be determined in consideration of the design specifications, manufacturing cost, user convenience, and the like of the image forming apparatus 10.

  Further, in each of the above-described embodiments, the image forming apparatus 10 employing the rotary developing device 20 has been described as an example. However, the present invention can also be applied to an image forming apparatus employing a tandem developing device. it can.

  Incidentally, the present invention can also determine whether or not the urging means functions normally, that is, whether or not a predetermined urging force is applied to the primary transfer roll 24 by the urging means. For example, when the period in which the fluctuation range of the voltage value detected by the voltage detection unit 74 exceeds a predetermined threshold is less than a predetermined period, it is determined that the urging means is functioning normally, and the voltage detection When the period during which the fluctuation range of the voltage value detected by the unit 74 exceeds a predetermined threshold is equal to or longer than the predetermined period, it is determined that the urging unit does not function normally.

1 is a schematic cross-sectional side view illustrating a configuration of an image forming apparatus according to a first embodiment. 1 is a partially enlarged view showing a main configuration of an image forming apparatus according to a first embodiment. 1 is a block diagram illustrating a main configuration of an electric system of an image forming apparatus according to a first embodiment. It is a functional block diagram which shows the functional structure of CPU which concerns on 1st Embodiment. 6 is a graph for explaining the principle of a method for determining whether or not an intermediate transfer belt is damaged. 6 is another graph for explaining the principle of a method for determining whether or not an intermediate transfer belt is damaged. It is a flowchart which shows the flow of a process of the damage judgment processing program which concerns on 1st Embodiment. It is a functional block diagram which shows the functional structure of CPU which concerns on 2nd Embodiment. It is a graph with which the frequency judgment part which concerns on 2nd Embodiment is used for description of the principle of the judgment method whether it outputs an average value calculation instruction | indication signal to an average value calculation part. It is another graph with which the frequency judgment part which concerns on 2nd Embodiment is used for description of the principle of the judgment method of whether an average value calculation instruction | indication signal is output to an average value calculation part. It is a flowchart which shows the flow of a process of the damage judgment processing program which concerns on 2nd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 12 Photosensitive drum (Image holding body)
13 Metal shaft 22 Intermediate transfer belt (transfer belt)
24 Primary transfer roll (transfer means)
70 Primary Transfer Roll Power Supply 72 Primary Transfer Roll Power Supply Control Unit 74 Voltage Detection Unit (Detection Unit)
76 CPU
82 UI panel (notification means)
86 Drive system control unit 98 Average value calculation unit 100 Ratio calculation unit 102 Damage determination unit (damage determination means) (drive stop means)
110 Frequency judging section (damage judging means)

Claims (7)

An image carrier for holding a toner image;
A transfer belt onto which the toner image held on the image carrier is transferred;
Transfer means for transferring the toner image to the transfer belt with the image carrier sandwiched between the transfer belt;
Detecting means for detecting a resistance value between the image holding body and the transfer means in a state where the transfer belt is sandwiched between the image holding body and the transfer means;
It is determined whether or not a period during which the fluctuation range of the resistance value detected by the detection unit exceeds a predetermined threshold is a predetermined period or more, and when it is determined that the period is equal to or more than the predetermined period, Damage determination means for determining that the transfer belt is damaged;
An image forming apparatus. The driving stop means for stopping the driving of the transfer belt when the transfer belt is driven and the damage determining means determines that the transfer belt is damaged. Image forming apparatus. The image forming apparatus according to claim 1, further comprising a notifying unit that notifies that the transfer belt is damaged when the damage determining unit determines that the transfer belt is damaged. The image forming apparatus according to claim 1, wherein the transfer unit is made of metal. When the image carrier rotates when transferring the toner image to the transfer belt, and the resistance value periodically varies,
The breakage determination means is when the frequency of the fluctuation of the resistance value exceeds the number of rotations per second of the image carrier, and when it is determined that the period is not less than the predetermined period, The image forming apparatus according to claim 1, wherein it is determined that the transfer belt is damaged. The image forming apparatus according to claim 1, wherein the fluctuation range is a value normalized by an average value of the resistance values. The detection means indicates the resistance value, and a known amount of electric power is applied between the image holding body and the transfer means in a state where the transfer belt is sandwiched between the image holding body and the transfer means. The image forming apparatus according to claim 1, wherein a voltage value or a current value between the image holding member and the transfer unit when applied is detected.

Images