JP2012226155A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To detect a detection part arranged on a belt in a short time and with high accuracy, even in a situation where a reinforcement tape is provided.SOLUTION: The image forming apparatus comprises: an intermediate transfer belt 228 configured to convey a toner image while holding it thereon; a detection mark 301 arranged on the intermediate transfer belt 228; a mark detection sensor 302 configured to detect the intermediate transfer belt 228 or the detection mark 301; a reinforcement tape 303 stuck onto the periphery of the intermediate transfer belt 228, which includes the detection mark 301, so as to cover the surface of the detection mark 301, for reinforcing an end edge of the intermediate transfer belt 228; and a control section 401 configured to control an image forming section at an image formation timing based on the detection result of the detection mark 301 obtained by the mark detection sensor 302. The reinforcement tape 303 is stuck so that the final end of the reinforcement tape 303 is arranged on the detection mark 301. The mark detection sensor 302 is able to detect the detection mark 301 via the reinforcement tape 303.

Description

  The present invention relates to an electrophotographic image forming apparatus having an endless belt, such as a color printer and a color copying machine.

  An electrophotographic image forming apparatus has a plurality of image forming units for speeding up, sequentially transferring images of different colors onto an intermediate transfer belt, which is an endless belt, and recording the image on the intermediate transfer belt A method of batch transfer onto a medium has been proposed. There has also been proposed a system in which images of different colors are sequentially transferred onto a recording medium held on a conveyor belt which is an endless belt. In recent years, color image forming apparatuses employing an electrophotographic system such as a color printer or a color copying machine have been required to improve the output image quality. Factors that determine the quality of the output image include the printing accuracy of the image on the recording medium and the overlay accuracy of each color toner image that affects the color of the image. However, due to changes in the environment in which the image forming apparatus is installed and factors that cause changes in various parts of the apparatus due to long-term use, misalignment of the leading edge writing position, expansion / contraction of the image, and the like occur, and printing accuracy decreases. Further, the overlay accuracy is lowered, and so-called color misregistration occurs. As a result, the quality of the output image is degraded. As a variation factor that causes the deterioration of the overlay accuracy, for example, in an image forming apparatus that employs an endless belt as an intermediate transfer member, a change in speed of the intermediate transfer belt that is an intermediate transfer member can be cited.

  Accordingly, various configurations have been proposed as methods for suppressing or correcting these fluctuations. For example, image formation start timing correction control is performed in which a mark or the like is formed at an arbitrary fixed position on the intermediate transfer belt, the mark or the like is detected by a detection sensor, and the image formation start timing of the image forming unit is corrected based on the detection result. It has been proposed (see, for example, Patent Document 1).

  On the other hand, in order to prevent cracks in the intermediate transfer belt, it is known to apply a reinforcing tape to improve the strength of the edge of the intermediate transfer belt. And in patent document 2, the following improvement proposal is proposed about the misdetection which concerns on the termination | terminus of this reinforcement tape. In Patent Document 2, the end of the reinforcing tape is first arranged at a position where it can be detected immediately after detection of the mark. Here, when a signal is detected for the first time, the detection sensor is set to a non-detection state for at least the time during which the belt moves by the distance between the mark and the end of the reinforcing tape. A signal detected thereafter is regarded as a mark detection signal. Thus, in Patent Document 2, for example, even if the end of the reinforcing tape is detected immediately after the start of detection, it is possible to prevent a situation in which it is erroneously detected as a mark.

JP 2000-199988 A JP 2007-310126 A

  However, the disclosure of Patent Document 2 has the following problems. The mark detection control proposed in Patent Document 2 needs to be detected by the detection sensor at least twice in order to remove the influence of noise, and it takes time until the mark is detected. During this time, the image forming operation cannot be performed, and the downtime of the apparatus increases.

  An object of the present invention is to solve at least one of such problems and other problems. An object of the present invention is to detect a detection unit arranged on a belt in a short time and with high accuracy even in a situation where the above-described reinforcing tape is provided.

  In order to solve the above-described problems, the present invention has the following configuration.

  (1) an endless belt that carries and conveys a toner image or a recording material, a detection member that is disposed on the endless belt, a detection unit that detects the endless belt or the detection member, and an endless belt An image based on a detection result of the detection member by the detection means, and a reinforcement member that is pasted on the circumference of the endless belt including the detection member to reinforce the edge, so as to cover the surface of the detection member An image forming apparatus comprising: a control unit that controls the image forming unit according to a forming condition, wherein the reinforcing member is attached so that a terminal portion of the reinforcing member is disposed on the detection member; The image forming apparatus according to claim 1, wherein the detection unit is capable of detecting the detection member via the reinforcing member.

  ADVANTAGE OF THE INVENTION According to this invention, the detection part arrange | positioned on a belt can be detected in a short time and with high precision also in the condition where a reinforcement tape is provided.

Sectional drawing and perspective view explaining the structure of the color image forming apparatus of Examples 1-4 The figure which shows the whole control part of Examples 1-4, The figure which shows an example of a structure of a mark detection sensor The figure which shows the output of the mark detection sensor in case peeling does not generate | occur | produce in the reinforcing tape of Examples 1-4. Flowchart showing the operation of the detection mark detection method of the first embodiment. The figure which shows the output of the mark detection sensor when peeling has generate | occur | produced in the reinforcing tape of Examples 1-3. Flowchart showing the operation of the detection mark detection method of the second embodiment. Flowchart showing the operation of the detection mark detection method of the third embodiment. The figure which shows the emitted light quantity of the light emitting element of the mark detection sensor of Example 3. The flowchart which shows operation | movement of the detection method of the detection mark of Example 4, The figure which shows the output of a mark detection sensor when peeling occurs in a reinforcement tape

  Hereinafter, the present invention will be described in detail based on the illustrated embodiments.

[Configuration and operation of color image forming apparatus]
FIG. 1A shows a color image forming apparatus provided with four color image forming units (image forming means). An intermediate transfer member (endless belt) which is an example of an electrophotographic color image forming apparatus is shown. FIG. 2 is a cross-sectional view of an adopted tandem color image forming apparatus. Here, the four colors are yellow Y, magenta M, cyan C, and black K. The operation of the image forming unit in the electrophotographic color image forming apparatus will be described with reference to FIG.

  The laser scanners 224Y, 224M, 224C, and 224K drive the exposure light according to the exposure time processed by the data control unit, which will be described later with reference to FIG. 2A (except for the case where each color is individually described below) , M, C, and K are omitted). The laser scanner 224 forms an electrostatic latent image by selectively exposing the photosensitive drum 222 charged by each injection charger 223 including the charging roller 223S. The photosensitive drum 222 is configured by applying an organic optical transmission layer to the outer periphery of the aluminum cylinder and is rotated by a driving force of a driving motor (not shown). The driving motor causes the photosensitive drum 222 to perform an image forming operation. Rotate counterclockwise accordingly. Each developing device 226 having the developing roller 226S develops and visualizes the electrostatic latent image formed on the photosensitive drum 222 with the toner sent from the toner container 225, and forms a single color toner image. Each developing device 226 can be detached.

  An appropriate bias voltage is applied to the primary transfer roller 227. By making a difference between the rotation speed of the photosensitive drum 222 and the rotation speed of the intermediate transfer belt 228, the primary transfer roller 227 efficiently transfers each single color toner image onto the intermediate transfer belt 228 (on the endless belt). This is called primary transfer. In this manner, the primary transfer roller 227 forms a multicolor toner image by superimposing the single color toner images on the photosensitive drum 222 on the intermediate transfer belt 228. The driving roller 237 receives a driving force of a driving motor (not shown) and rotates in the clockwise direction, and the intermediate transfer belt 228 is transported and driven by the driving roller 237 and is driven and transported by the driven roller 236.

  Then, the single color toner image is superimposed on the intermediate transfer belt 228 for each station, and the superimposed multicolor toner image is conveyed to the secondary transfer roller 229 a as the intermediate transfer belt 228 rotates. Further, the recording material 211 is fed from the paper feed cassette 212a by the paper feed roller 238a, and is nipped and transported to the secondary transfer roller 229a by a pair of transport rollers 239. The recording material 211 is multicolored on the intermediate transfer belt 228. Transfer the toner image. The conveyance sensor 240 detects the passage of the recording material 211. An appropriate bias voltage is applied to the secondary transfer roller 229a to electrostatically transfer the toner image. This is called secondary transfer. The secondary transfer roller 229a contacts the recording material 211 at the position 229a while transferring the multicolor toner image on the recording material 211, and is separated to the position 229b after the printing process. The recording material 211 may be disposed on the paper feed tray 212b. In that case, the recording material 211 is fed from the paper feed tray 212b by the paper feed roller 238b and is fed to the secondary transfer roller 229a by a pair of transport rollers 239. Nipped and transported. The conveyance sensor 240 detects whether or not the recording material 211 is nipped and conveyed at a desired timing. When the recording material 211 is not conveyed, various conveyance defects (jams) (for example, conveyance delay jam) are detected. Notify a video controller (not shown).

  The fixing device 231 adds a fixing roller 232 for heating the recording material 211 and a pressing member for bringing the recording material 211 into pressure contact with the fixing roller 232 in order to melt and fix the multicolor toner image transferred to the recording material 211 on the recording material 211. A pressure roller 233 is provided. The fixing roller 232 and the pressure roller 233 are formed in a hollow shape, and heaters 234 and 235 are incorporated therein, respectively. The fixing device 231 conveys the recording material 211 holding the multicolor toner image by the fixing roller 232 and the pressure roller 233 and applies heat and pressure to fix the toner on the recording material 211. The recording material 211 after toner fixing is then discharged onto a discharge tray (not shown) by a discharge roller (not shown), and the image forming operation is completed. The cleaning unit 230 cleans the toner remaining on the intermediate transfer belt 228, and the toner (residual toner) remaining after transferring the four-color multicolor toner image formed on the intermediate transfer belt 228 to the recording material 211. ) Is stored in a cleaner container (not shown).

[Detection mark and reinforcing tape]
FIG. 1B is a perspective view of the color image forming apparatus of this embodiment. The configuration excluding 301, 302, and 303 in FIG. 1B operates in the same manner as the operation described in FIG. The detection mark 301 (detection member) is a detection mark that is disposed by being attached to an end portion on the intermediate transfer belt 228. The mark detection sensor 302 (detection means) is a light reflection type sensor that detects the detection mark 301. The reinforcing tape 303 (reinforcing member) is a tape that is affixed and disposed to prevent the occurrence of cracks at the edge of the intermediate transfer belt 228. The reinforcing tape 303 is disposed on the detection mark conveyance periphery and is disposed on the surface of the detection mark 301.

[Configuration of control unit]
FIG. 2A is a diagram illustrating the entire control unit of this embodiment. A data control unit 401 (control means) controls and manages the entire apparatus composed of a one-chip microcomputer or the like. A host I / F unit 402 communicates with a printer and a personal computer (hereinafter referred to as a PC). The memory 403 holds print data, various parameters, various information, and the like. The image formation control unit 404 converts print data sent from the PC to the printer into data suitable for the method of the printer engine (image formation unit). A sensor 405 detects the state of each part of the printer by a paper detection sensor, a mark detection sensor 302, and the like. The drive control unit 406 performs drive control of the printer engine actuators, laser, high-voltage power supply, and the like.

  When data to be printed (print data) is sent from the PC to the printer via the host I / F unit 402, the image formation control unit 404 converts the print data into data according to the printer engine system. When the data conversion by the image formation control unit 404 is completed and printing is possible, the drive control unit 406 starts driving the photosensitive drum 222 and the intermediate transfer belt 228 connected to a drive unit (not shown) such as a motor or a gear. To do. Next, an image signal of each color is sent to the laser scanner 224 of each color, an electrostatic latent image is formed on the photosensitive drum 222, and the toner is developed by the developing device 226. Thereafter, the primary transfer and the secondary transfer described with reference to FIG. In FIG. 1, images are sequentially formed in the order of yellow Y, magenta M, cyan C, and black K.

[Configuration of mark detection sensor]
FIG. 2B is a diagram for explaining an example of the configuration of the mark detection sensor 302 of this embodiment. The mark detection sensor 302 includes a light emitting element 501 such as an LED that emits light, a light receiving element 502 such as a photodiode, a semiconductor integrated circuit (not shown) that processes received light data (hereinafter referred to as IC), and the like. Consists of a holder that does not. The light receiving element 502 detects the intensity of reflected light from the intermediate transfer belt 228. Although FIG. 2B is configured to detect irregularly reflected light, the present invention is not limited to this, and regular reflected light may be detected. An optical element such as a lens (not shown) may be used for coupling the light emitting element 501 and the light receiving element 502. In the present embodiment, a configuration for detecting the irregularly reflected light described in FIG. 2B will be described as an example.

[When there is no peeling on the reinforcing tape]
FIG. 3 is a diagram for explaining a detection signal (hereinafter referred to as an output value) that is a detection result of the mark detection sensor 302 when the reinforcing tape 303 (303a, 303b) of this embodiment is not peeled off. An arrow A indicates the conveyance direction of the intermediate transfer belt 228. The reinforcing tape 303 is arranged so that the reinforcing tape 303a on the downstream side in the transport direction of the intermediate transfer belt 228 overlaps the reinforcing tape 303b on the upstream side in the transport direction of the intermediate transfer belt 228, and the end portion (end portion) of the reinforcing tape 303a is disposed. It is arranged on the detection mark 301. S1 is an output value of reflected light of the mark detection sensor 302 in the detection mark portion (hereinafter also referred to as a mark detection sensor output), and S2 is an output value of reflected light of the mark detection sensor 302 of the intermediate transfer belt portion. In this embodiment, as an example, the following description will be made assuming that the irregular reflectance of the detection mark 301 is higher than the irregular reflectance of the intermediate transfer belt 228 and the irregular reflectance of the toner. Further, the reinforcing tape 303 is a transparent member, for example, and the output value of the reflected light of the mark detection sensor 302 in the reinforcing tape 303 in the portion without the detection mark 301 is equal to the output value of the mark detection sensor 302 in the intermediate transfer belt portion. Suppose that If the mark detection sensor 302 outputs a signal (mark detection sensor output in FIG. 3) of a certain threshold value or more, the reinforcing tape 303 may be colorless and transparent or colored and transparent. Further, a member that transmits light from the light emitting element 501 at a certain level may be used. As described above, the mark detection sensor 302 may be configured to be able to detect the detection mark 301 via the reinforcing tape 303. Due to this difference in reflectivity, the mark detection sensor output S configured to detect irregularly reflected light has a mark detection sensor output S1 that is reflected light of the detection mark portion as compared to the mark detection sensor output S2 of the intermediate transfer belt portion. High output.
S1> S2 Formula (1-1)

  Sth is a threshold value (predetermined threshold value), and the data control unit 401 arbitrarily sets the threshold value Sth in the range of St> Sth> S2, and the data control unit 401 sequentially compares the threshold value Sth and the mark detection sensor output S. Then, the period time between the detection marks 301 is calculated. Details of the calculation method of the cycle time will be described later with reference to FIG. Here, St is the output value of the reflected light of the mark detection sensor 302 at the toner adhesion portion (the portion where the toner is adhered), and details will be described later with reference to FIG. The mark detection sensor 302 may be configured to detect regular reflection light. When the regular reflection light is detected and the regular reflectance of the detection mark 301 is lower than the regular reflectance of the intermediate transfer belt 228, the mark detection sensor output S becomes St <Sth <S2.

[Detection method of detection mark]
FIG. 4 is a flowchart for explaining the operation of the detection method of the detection mark 301 of this embodiment. In step (hereinafter simply referred to as S) 701, the data control unit 401 sets zero as an initial value to a time counter t that counts time, that is, initializes the time counter t. In S702, the data control unit 401 sets zero as an initial value for the parameters TR and TF, that is, initializes the memory. Here, TR means the timing when the rising edge of the detection signal of the mark detection sensor 302 is detected, and TF means the timing when the falling edge of the mark detection sensor 302 is detected. In step S703, the data control unit 401 starts the count operation of the time counter t. In step S704, the data control unit 401 determines whether the output value S of the mark detection sensor 302 is equal to or greater than the threshold value Sth. Since the threshold value Sth has been described with reference to FIG. 3, the description thereof is omitted here. If the data control unit 401 determines in step S704 that the output value S of the mark detection sensor 302 is greater than or equal to the threshold value Sth, the data control unit 401 stores the value of the time counter t in the rising detection timing TR of the mark detection sensor 302 in step S705. In S704, when the data control unit 401 determines that the output value S of the mark detection sensor 302 is smaller than the threshold value Sth, the data control unit 401 determines that the detection mark 301 is not detected, and performs the process of S704.

  In step S706, the data control unit 401 determines whether the output value S of the mark detection sensor 302 is smaller than the threshold value Sth. When the data control unit 401 determines in S706 that the output value S of the mark detection sensor 302 is smaller than the threshold value Sth, the value of the time counter t is stored in the falling detection timing TF of the mark detection sensor 302 in S707. If the data control unit 401 determines in step S706 that the output value S of the mark detection sensor 302 is equal to or greater than the threshold value Sth, the data control unit 401 determines that the detection mark 301 is detected and performs the processing in step S706.

In S708, the data control unit 401 uses the value stored in TR in S705 and the value stored in TF in S707 to calculate the timing T of the detection mark 301 based on the following calculation formula, and ends the flowchart.
T = (TR + TF) / 2 Formula (1-2)

  The data control unit 401 sequentially obtains the timing T of the detection mark 301 by the calculation process described above, and calculates the difference between the timings T as the detection mark interval cycle time (detection mark cycle data). The data control unit 401 calculates the correction amount of the writing position of each color image based on the calculated detection mark cycle data T1.

Specifically, the difference between the calculated detection mark cycle data T1 and the initial value T0 of the detection mark cycle data stored in the memory 403 in advance is calculated. Further, the diameter of the driving roller 237 stored in the memory 403 in advance is D, the thickness of the intermediate transfer belt 228 is A, and the circumferential length of the intermediate transfer belt 228 is L. Then, based on the calculated difference value (T1−T0), the diameter D, the thickness A, and the circumference L, a correction amount (hereinafter referred to as an image formation timing correction amount) of the writing position of each color image can be calculated. it can. The image forming timing correction amount of the second image forming unit M is Tm, and the image forming timing correction of the third image forming unit C is based on the image forming timing (image forming condition) of the leading image forming unit Y. The amount is Tc, and the image formation timing correction amount of the fourth image forming unit K is Tk. Then, the image formation timing correction amount for each color is calculated as follows. For example, “1 × π × (D + A) / L” is an arrangement interval along the conveyance direction of the intermediate transfer belt 228 between the photosensitive drum 222Y of the reference color yellow Y and the photosensitive drum 222M of magenta M. Here, the arrangement interval is, for example, the distance between the center points (shown as “+” in the drawing) of the photosensitive drum 222 in the sectional view of FIG. “2 × π × (D + A) / L” and “3 × π × (D + A) / L” are also the arrangement intervals described above for cyan C and black K.
Tm = (T1-T0) × 1 × π × (D + A) / L (1-3)
Tc = (T1-T0) × 2 × π × (D + A) / L (1-4)
Tk = (T1-T0) × 3 × π × (D + A) / L (1-5)
Then, the image formation control unit 404 is appropriately controlled according to the correction amount.

[When peeling occurs on the reinforcing tape]
FIG. 5 is a diagram for explaining the output of the mark detection sensor 302 when peeling occurs on the reinforcing tape 303 of this embodiment. The toner 101 is toner attached to the adhesive surface of the reinforcing tape 303. St is the output value of the reflected light of the mark detection sensor 302 at the toner adhesion portion (that is, the reinforcing tape peeling portion). The reinforcing tape 303a may be peeled off from the end portion with aging. When the end portion of the reinforcing tape 303a is peeled off, the toner scattered around adheres to the adhesive surface of the reinforcing tape 303a, and the reflectance changes. Since the irregular reflectance of the detection mark 301 is higher than the irregular reflectance of the toner, the output value St of the reflected light of the mark detection sensor 302 at the toner adhesion portion (reinforcing tape peeling portion) is lower than the reflected light output S1 of the detection mark portion. Is done.
St <S1 Formula (1-6)

  The data control unit 401 arbitrarily sets the threshold value Sth in advance within the range of St> Sth> S2, sequentially compares the threshold value Sth and the output value S of the mark detection sensor 302, and calculates the detection mark interval cycle time. Since the details of the calculation method of the cycle time have been described with reference to FIG. 4, the description thereof is omitted here. Since the threshold value Sth is set to a value smaller than St, the mark detection sensor 302 detects the detection mark 301 even if the reinforcing tape 303 is peeled off and the toner adheres to the adhesive surface of the reinforcing tape 303. Can be avoided.

  As described above, according to the present embodiment, the end portion of the reinforcing tape is arranged on the mark, and the detection mark 301 is detected by the mark detection sensor 302. Can be detected in a short time and with high accuracy.

  Only differences from the first embodiment will be described. 1 to 3 and FIG. 5 operate in the same manner as in the first embodiment, and a description thereof will be omitted. In the first embodiment, the threshold value Sth is an arbitrary predetermined value. The present embodiment is characterized in that the threshold value Sth is controlled based on the output value St of the reflected light of the mark detection sensor 302 at the toner adhesion portion.

  The threshold value Sth needs to be set lower than the output value St of the reflected light of the mark detection sensor 302 at the toner adhesion portion (Sth <St). On the other hand, the threshold value Sth needs to be set higher than the output value S2 of the reflected light of the mark detection sensor 302 of the intermediate transfer belt portion in order to reduce the influence of noise from the intermediate transfer belt 228 portion (S2 < Sth). Since the peeling of the reinforcing tape 303 occurs with deterioration over time, the intermediate transfer belt portion is set when the threshold value Sth is set low assuming the output value St of the reflected light of the mark detection sensor 302 at the time of toner adhesion at the early stage of the product life. Susceptible to noise from.

[Detection method of detection mark]
FIG. 6 is a flowchart for explaining the operation of the detection method of the detection mark 301 of this embodiment. Since S801 to S805 operate in the same manner as S701 to S705 in FIG. However, the threshold value Sth in S804 is a variable and is a value set in the previous operation of the flowchart. Details of the setting method will be described later in S8083. In step S8051, the data control unit 401 determines whether the output value S of the mark detection sensor 302 matches the output value S1 of the reflected light of the detection mark unit detected last time. Here, S1 is a value set in S8082 of the previous flowchart operation, and details of the setting method will be described later in S8082. If the data control unit 401 determines in step S8051 that the output value S of the mark detection sensor 302 matches the output value S1 of the reflected light of the detection mark unit detected last time, the data control unit 401 changes the output value S of the mark detection sensor 302 in step S8052. Store in St. St is a variable for calculating the output value of the reflected light of the mark detection sensor 302 at the toner adhesion portion. If the data control unit 401 determines in step S8051 that the output value S of the mark detection sensor 302 does not match the reflected light output S1 of the detection mark unit detected last time, the data control unit 401 determines that the detection mark 301 has not been detected, and in step S8051. Process.

  In step S8053, the data control unit 401 determines whether the output value S of the mark detection sensor 302 is smaller than the variable St. In S8053, when the data control unit 401 determines that the output value S of the mark detection sensor 302 is smaller than the variable St, the data control unit 401 updates the variable St to the output value S of the mark detection sensor 302 in S8054. If the data control unit 401 determines in step S8053 that the output value S of the mark detection sensor 302 is greater than or equal to the variable St, the process advances to step S8055. In step S8055, the data control unit 401 determines whether the time counter t is greater than (TR + t1). t1 is a time for detecting the detection mark 301, calculated based on the length of the detection mark 301 in the conveyance direction and the conveyance speed of the intermediate transfer belt 228, and is arbitrarily set. If the data control unit 401 determines in S8055 that the time counter t is greater than TR + t1, it determines in S806 whether the output value S of the mark detection sensor 302 is smaller than the threshold value Sth. If the data control unit 401 determines in step S8055 that the time counter t is equal to or less than TR + t1, the data control unit 401 determines that detection of the detection mark 301 has not been completed, and returns to step S8053. S807 and S808 operate in the same manner as S707 and S708 in FIG.

In S8082, the data control unit 401 sets the maximum value of the output value S of the mark detection sensor 302 to the output value S1 of the reflected light of the detection mark unit. It is assumed that the data control unit 401 monitors the output value S after starting detection by the mark detection sensor 302 and stores the maximum value of the output value S in the memory 403. In step S8083, the data control unit 401 sets the threshold value Sth.
St × G Formula (2-1)
Set. St is a variable in which the output value of the reflected light of the mark detection sensor 302 at the toner adhesion portion is stored by the operation of S8054. G is a correction gain, and is arbitrarily set within a range of 0 <G <1. Thereafter, the flowchart is terminated, and the process returns to the start (S801) of the flowchart. When this flowchart is started again, the threshold value Sth set in S8083 is used for the determination performed by the data control unit 401 in S804.

  As described above, the end of the reinforcing tape is arranged on the mark, the threshold value Sth is controlled based on the output value of the reflected light of the mark detection sensor 302 at the toner adhesion portion, and the detection mark 301 is detected by the mark detection sensor 302. . Thereby, according to the present Example, the detection part arrange | positioned on a belt can be detected in a short time and with high precision also in the condition where a reinforcement tape is provided. Furthermore, the influence of noise can be reduced.

  Only differences from the first and second embodiments will be described. 1 to 3 and FIG. 5 operate in the same manner as in the first embodiment, and a description thereof will be omitted. In the first and second embodiments, the light emission amount of the light emitting element 501 of the mark detection sensor 302 is set to an arbitrary predetermined value. However, this embodiment is characterized in that the light emission amount of the light emitting element 501 is controlled based on the output value of the reflected light of the mark detection sensor 302 in the detection mark portion. This is because as the printing operation is performed, paper dust or the like of the recording material 211 adheres to the mark detection sensor 302, and the sensitivity of the mark detection sensor 302 may decrease.

[Mark detection method]
FIG. 7 is a flowchart for explaining the operation of the detection method of the detection mark 301 of this embodiment. Steps S901 to S9083 operate in the same manner as steps S801 to S8083 in FIG. In step S9084, the data control unit 401 sets the light emission amount PWM of the light emitting element 501 of the mark detection sensor 302 to a value calculated by the following calculation formula. In this embodiment, as an example, the control method for the light emission amount of the light emitting element 501 of the mark detection sensor 302 will be described below as PWM control for changing the light emission amount by changing the pulse width of the control signal.
PWM = PWM + f (Stgt-S1) Formula (3-1)

  S1 is the output value of the reflected light of the mark detection sensor 302 of the detection mark part, and Stgt is the target value of the output value of the reflected light of the mark detection sensor 302 of the detection mark part (hereinafter referred to as the mark detection sensor output target value). F (Stgt-S1) is a function having the difference between Stgt and S1 as a variable. The mark detection sensor output target value Stgt of the detection mark portion is a value arbitrarily set in advance to satisfy Stgt> Sth. Thereafter, this flowchart is ended, and the process returns to the start of this flowchart again. When the flowchart is started again and the mark detection sensor 302 detects the detection mark 301, the light emitting element 501 is caused to emit light using the light emission amount PWM calculated in the previous S9084.

[Light intensity of light emitting element]
FIG. 8 is a diagram for explaining the light emission amount of the light emitting element 501 of the mark detection sensor 302 of this embodiment. The horizontal axis represents the difference between the mark detection sensor output target value Stgt of the detection mark portion and the output value S1 of the reflected light of the mark detection sensor 302 of the detection mark portion, and the vertical axis represents the function f having Stgt-S1 as a variable f. (Stgt-S1). When (Stgt-S1)> 0, it means that the output value of the reflected light of the mark detection sensor 302 is lower than the target value (the amount of emitted light is small). On the other hand, if (Stgt−S1) <0, it means that the reflected light output of the mark detection sensor 302 is higher than the target value (the amount of emitted light is large). Here, as an example, description will be made assuming that Stgt = 2.6 [V], S1 before control = 2.5 [V], and PWM before control = 50 [%]. At this time, the difference between the mark detection sensor output target value Stgt of the detection mark portion and the reflected light output S1 of the mark detection sensor 302 of the detection mark portion is:
Stgt-S1 = 2.6-2.5 = 0.1 [V]> 0 Formula (3-2)
It becomes.

The function f (Stgt-S1) at this time is f (Stgt-S1) = 10 [%] according to FIG. 8 (where Stgt-S1 = 0.1 [V]) (3-3)
And the PWM after control is
PWM = PWM + f (Stgt-S1) = 50 [%] + 10 [%] = 60 [%] (3-4)
Is calculated. The function f (Stgt-S1) described with reference to FIG. 8 is an example, and the function f (Stgt-S1) is not limited to this as long as the value of f (Stgt-S1) is uniquely determined. For example, a non-linear function may be used. According to Expression (3-4), the data control unit 401 increases the light emission amount of the light emitting element 501 of the mark detection sensor 302 from 50 [%] to 60 [%]. As a result, the output value S1 of the reflected light of the mark detection sensor 302 in the detection mark portion increases from 2.5 [V] to 2.6 [V], and the mark detection sensor output target value Stgt = 2. It matches 6 [V]. Even if contamination that lowers the sensitivity of the mark detection sensor 302 occurs by sequentially executing FIG. 7, the output value of the reflected light of the mark detection sensor 302 in the detection mark portion is controlled to a constant value, and the detection accuracy is reduced. Can be prevented.

  As described above, the end of the reinforcing tape is arranged on the mark, and the mark detection sensor 302 detects the mark by controlling the light emission amount of the light emitting element based on the output value of the reflected light of the mark detection sensor 302 of the detection mark portion. To do. Thereby, according to the present Example, the detection part arrange | positioned on a belt can be detected in a short time and with high precision also in the condition where a reinforcement tape is provided. Furthermore, the influence of dirt on the mark detection sensor 302 can be reduced.

  Only differences from the first to third embodiments will be described. Since FIG. 1 to FIG. 3 operate in the same manner as the first embodiment, description thereof is omitted. In the first to third embodiments, the mark detection sensor 302 detects the detection mark 301 based on the rising detection timing and the falling detection timing of the detection mark 301. However, the present embodiment is characterized in that the mark detection sensor 302 detects the detection mark 301 based on the falling detection timing that is downstream in the transport direction of the detection mark 301. This is because peeling of the reinforcing tape 303 does not always occur only in the detection mark area. As the aging deteriorates, the peeling progresses, and the reinforcing tape 303 may be peeled off to the outside of the detection mark region, and the toner may adhere.

[Detection method of detection mark]
FIG. 9A is a flowchart for explaining the operation of the detection method of the detection mark 301 of this embodiment. S1101 operates in the same manner as S701 in FIG. In S1102, the data control unit 401 sets zero as an initial value for the parameter TF, that is, initializes the memory. TF means the timing when the fall of the mark detection sensor 302 is detected. Since S1103 and S1104 to S1105 operate in the same manner as S703 and S706 to S707 in FIG. In step S1106, the data control unit 401 calculates the timing T of the detection mark 301 based on the following calculation formula, and ends this flowchart.
T = TF ... Formula (4-1)

  By the calculation process described above, the data control unit 401 sequentially obtains the timing T of the detection mark 301 and calculates the difference between the timings T as the cycle time of the detection mark interval.

[When peeling occurs on the reinforcing tape]
FIG. 9B is a diagram for explaining the output of the mark detection sensor 302 when peeling occurs on the reinforcing tape 303 of this embodiment. The toner 1201 is a toner attached to the adhesive surface of the reinforcing tape 303a. St is the output value of the reflected light of the mark detection sensor 302 at the toner adhesion portion. When the peeling of the reinforcing tape 303a due to aging progresses to the outside of the detection mark area and the toner adheres to the adhesive surface, the reflectance changes to the area without the detection mark indicated by L in the drawing. In this state, the detection method of the detection mark 301 described in FIG. 9A is executed, the detection mark timing T is sequentially obtained based on the falling detection timing of the detection mark 301, and the difference between each timing T is detected. Calculated as the interval time. Based on the calculated detection mark cycle data, the data control unit 401 calculates the correction amount of the writing position of each color image. Then, the image formation control unit 404 is appropriately controlled according to the correction amount.

  In the present embodiment, as described in the second embodiment, the threshold value Sth may be controlled based on the output value St of the reflected light of the mark detection sensor 302 at the toner adhesion portion. Furthermore, as described in the third embodiment, the light emission amount of the light emitting element may be controlled based on the reflected light output value S1 of the mark detection sensor 302 of the detection mark portion.

  As described above, the end portion of the reinforcing tape is arranged on the detection mark, and the detection mark is detected based on the falling detection timing that is downstream in the conveyance direction of the detection mark. Thereby, according to the present Example, the detection part arrange | positioned on a belt can be detected in a short time and with high precision also in the condition where a reinforcement tape is provided. Furthermore, even when the peeling of the reinforcing tape has progressed out of the area of the detection part, the detection part arranged on the belt can be detected in a short time and with high accuracy.

[Other Examples]
Although this embodiment is described using a four-color image forming apparatus, a multi-color image forming apparatus provided with a belt-shaped intermediate transfer member is not limited to four colors.
In this embodiment, a tandem color image apparatus is used for explanation. However, the color image forming apparatus provided with a belt-like intermediate transfer member is not limited to the tandem system. For example, a rotary color image forming apparatus including a belt-like intermediate transfer member may be used.
Although this embodiment has been described using a mark detection sensor that detects irregularly reflected light, a configuration that detects regular reflected light may be used.
In the present embodiment, the detection mark attached to the intermediate transfer member is described. However, the detection mark may be printed on the intermediate transfer member. Alternatively, the detection mark may be formed by cutting the intermediate transfer member.
In this embodiment, the control method of the light emitting element of the mark detection sensor is described as PWM control. However, the control is not limited to PWM control as long as the amount of emitted light can be controlled. For example, PAM control in which the pulse amplitude of the control signal is changed may be used.
In the present embodiment, the reinforcing tape is attached in a clockwise direction so that the end of the intermediate transfer belt on the downstream side in the transport direction overlaps the reinforcing tape on the upstream side in the transport direction. However, the reinforcing tape may be attached so that the end of the intermediate transfer belt on the upstream side in the conveying direction overlaps the reinforcing tape on the downstream side in the conveying direction, that is, the reinforcing tape is counterclockwise. In this case, in order to cope with the case where the peeling of the reinforcing tape reaches the outside of the detection mark area as in the fourth embodiment, the parameter TR is initialized in S1102 of FIG. 9A, and T = TR is set in S1106.
In this embodiment, different color images are sequentially transferred onto an intermediate transfer belt that is an endless belt, and the images on the intermediate transfer belt are collectively transferred onto a recording material. However, different color images may be sequentially transferred onto the recording material carried and conveyed by the conveying belt which is an endless belt.
In the other embodiments as described above, the detection unit arranged on the belt can be detected in a short time and with high accuracy even in a situation where the reinforcing tape is provided.

228 Intermediate transfer belt 301 Detection mark 302 Mark detection sensor 303 Reinforcing tape 401 Data control unit

Claims (11)

An endless belt for carrying and conveying a toner image or a recording material;
A detection member disposed on the endless belt;
Detection means for detecting the endless belt or the detection member;
A reinforcing member that is attached so as to cover the surface of the endless belt on the circumference of the endless belt including the detecting member in order to reinforce the edge of the endless belt;
An image forming apparatus comprising: a control unit that controls the image forming unit according to an image forming condition based on a detection result of the detection member by the detection unit;
The reinforcing member is affixed so that a terminal portion of the reinforcing member is disposed on the detecting member, and the detecting means can detect the detecting member via the reinforcing member. Image forming apparatus.   The said control means calculates the timing which detected the said detection member based on the timing which detected the rising of the detection signal which is the detection result of the said detection member by the said detection means, and the timing which detected the fall. Item 2. The image forming apparatus according to Item 1.   The image forming apparatus according to claim 2, wherein the control unit detects the rising timing and the falling timing by comparing the detection signal with a predetermined threshold value. The reinforcing member is disposed such that an end of the reinforcing member on the downstream side in the transport direction of the endless belt overlaps the reinforcing member on the upstream side in the transport direction,
The image according to claim 1, wherein the control unit calculates a timing at which the detection member is detected based on a timing at which the detection unit detects a falling edge of a detection signal that is a detection result of the detection member. Forming equipment.   The image forming apparatus according to claim 4, wherein the control unit detects the falling timing by comparing the detection signal with a predetermined threshold value. The reinforcing member is disposed such that an upstream end of the reinforcing member in the transport direction of the endless belt overlaps the reinforcing member on the downstream side in the transport direction,
The image forming apparatus according to claim 1, wherein the control unit calculates a timing at which the detection member is detected based on a timing at which a rising edge of a detection signal that is a detection result of the detection member by the detection unit is detected. apparatus.   The image forming apparatus according to claim 6, wherein the control unit detects the rising timing by comparing the detection signal with a predetermined threshold value.   8. The predetermined threshold value is smaller than a detection result obtained by detecting a portion to which the toner has been adhered by the detection means when the toner has adhered to the end portion of the reinforcing member. The image forming apparatus according to claim 1.   The image forming apparatus according to claim 8, wherein the control unit sets the predetermined threshold based on a detection result of a portion to which the toner is adhered by the detection unit. The detection means has a light emitting element for irradiating the detection member with light,
The image forming apparatus according to claim 1, wherein the control unit sets a light emission amount of the light emitting element based on a detection result of the detection member by the detection unit.   The image forming apparatus according to claim 1, wherein the image forming condition is a timing of image formation by the image forming unit.

Images