Detection device, image forming apparatus

Abstract

To resolve such a problem that, when abnormality is determined to occur on the basis of a result of detection by a sensor, it is difficult to determine whether the cause of the abnormality is due to a sheet or the sensor.SOLUTION: When determining occurrence of abnormality on the basis of a detection result by detection means, control means turns on the detection means after tuning it off and reacquires the detection result by the detection means, so as to determine whether the cause of the abnormality is due to a sheet or the detection means.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to a detection device for detecting a sheet.

Background Art

[0002] Conventionally, in an image forming apparatus, as shown in Patent Document 1, a method of detecting the inclination of a conveyed sheet by a sensor and correcting the relative positional relationship between the sheet and the formed image is known.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, when it is determined that an abnormality has occurred based on the result detected by the sensor, it has been difficult to determine whether the cause of the abnormality is due to the sheet or the sensor.

[0005] The invention according to the present application has been made in view of the above situation, and an object thereof is to provide a device capable of discriminating the cause of an abnormality.

Means for Solving the Problems

[0006] In order to achieve the above object, a detection means for detecting a sheet, and based on the detection result of the detection means, control means for detecting an end portion of the sheet in a direction orthogonal to the conveyance direction of the sheet, are provided, and when the control means determines that an abnormality has occurred based on the detection result of the detection means, after turning off the power of the detection means, the power of the detection means is turned on, and the detection result by the detection means is acquired again If, based on the detection results obtained again, it is determined that an abnormality has occurred again, the detection means will determine that the abnormality is caused by the aforementioned means. and discriminated, which is characterized in that.

Effects of the Invention

[0007] According to the present invention, the cause of the abnormality can be identified. [Brief explanation of the drawing]

[0008] [Figure 1] Schematic diagram of an image forming apparatus [Figure 2] Control block diagram of an image forming apparatus [Figure 3] Schematic diagram showing the position of the seat and the line sensor. [Figure 4] Schematic diagram showing the position of the seat and the line sensor. [Figure 5] A flowchart showing a method for correcting the image formation position. [Figure 6] A flowchart showing how to identify the cause of an anomaly. [Figure 7] A flowchart showing how to identify the cause of an anomaly. [Modes for carrying out the invention]

[0009] Embodiments of the present invention will be described below with reference to the drawings. Note that the following embodiments are not intended to limit the invention as defined in the claims, and not all combinations of features described in the embodiments are necessarily essential to the solution of the invention. [Examples]

[0010] (Image forming apparatus) Figure 1 is a schematic diagram of the image forming apparatus 201. Figure 2 is a control block diagram of the image forming apparatus 201. The operation of the image forming apparatus 201 will be explained using Figures 1 and 2.

[0011] The control unit 401 is a control means that controls the operation of the image forming apparatus 201. It exchanges information such as image data and image forming condition settings with the host device 900, which may be a personal computer, image scanner, or facsimile, and the operation unit 730. The control unit 401 also performs signal processing and sequence control for various process equipment.

[0012] The image forming apparatus 201 is a tandem, intermediate transfer type laser beam printer that utilizes an electrophotographic process. The image forming apparatus 201 forms an image on a recording medium sheet S that corresponds to the image data output from the host device 900 connected to the control unit 401.

[0013] The image forming apparatus body 201A includes an image forming unit 201B for forming an image on a sheet. Above the image forming apparatus body 201A, an image reading device 202 is positioned approximately horizontally to the image forming apparatus body 201A. A discharge space V for sheet discharge is formed between the image reading device 202 and the image forming apparatus body 201A.

[0014] The cassette feeding unit 230 includes a feeding cassette 1 for loading sheets S, and a pickup roller 2 for feeding the sheets S loaded in the feeding cassette 1. The cassette feeding unit 230 also includes a separation unit consisting of a feed roller 3 and a retard roller 4 for separating the sheets S fed out from the pickup roller 2.

[0015] The manual feed unit 235 includes a manual feed tray 5 for loading sheets S, and a pickup roller 502 for feeding the sheets S loaded in the manual feed tray 5. The manual feed unit 235 also includes a separation unit consisting of a feed roller 503 and a retard roller 504 for separating the sheets S fed out by the pickup roller 502.

[0016] The image forming unit 201B, which serves as an image forming means, comprises a laser scanner 210 and four process cartridges 211 that form an image using four toners: yellow (Y), magenta (M), cyan (C), and black (K). Each process cartridge 211 includes a photosensitive drum 212, a charger 213 which is a charging means, and a developer 214 which is a developing means. The image forming unit 201B also includes a toner cartridge 215 that supplies toner to the developer 214. Furthermore, it includes a secondary transfer unit 201D and a fixing unit 201E located above the process cartridges 211.

[0017] The secondary transfer unit 201D includes an intermediate transfer belt 216 wound around a driving roller 216a and a tension roller 216b. An image carrier roller 219 that contacts the intermediate transfer belt 216 is provided at a position inside the intermediate transfer belt 216 and opposite to the photosensitive drum 212. The intermediate transfer belt 216 is rotated in the direction of the arrow by a driving roller 216a driven by a driving unit (not shown). A secondary transfer roller 217 for transferring the image formed on the intermediate transfer belt 216 to the sheet S is provided at a position opposite to the driving roller 216a of the secondary transfer unit 201D.

[0018] A fixing unit 201E is arranged above the secondary transfer roller 217, and a first discharge roller pair 225a, a second discharge roller pair 225b, and a duplex reversing unit 201F are arranged above the fixing unit 201E. The duplex reversing unit 201F is provided with a reversing roller pair 222 capable of forward and reverse rotation and a retransfer path R for retransferring the sheet S with an image formed on the first surface to the image forming unit 201B again.

[0019] An operation unit 730 as reception means for receiving operations from the user is provided above the image forming apparatus 201. The operation panel is a touch panel type that not only displays but also has an input function.

[0020] (Operation of the image forming apparatus) Next, the image forming operation of the image forming apparatus 201 will be described. First, when the image forming apparatus 201 receives image data to be printed, the image data is processed by image processing and then converted into an electrical signal and transmitted to the laser scanner 210 of the image forming unit 201B. In the image forming unit 201B, the surface of the photosensitive drum 212 uniformly charged to a predetermined polarity and potential by the charger 213 is sequentially exposed by the laser scanner 210. As a result, electrostatic latent images of yellow, magenta, cyan, and black are sequentially formed on the photosensitive drums of the respective process cartridges 211.

[0021] The electrostatic latent image formed on the photosensitive drum 212 is developed by the respective color developer units 214 to visualize it as an image. The images formed on each photosensitive drum are sequentially transferred onto the intermediate transfer belt 216 by applying a primary transfer bias to the primary transfer roller 219. As a result, a color image is formed on the intermediate transfer belt 216.

[0022] In parallel with the image forming operation, the sheets S are transported one by one to the register roller pair 240 by the cassette feeding unit 230 or the manual feed unit 235. The skew of the sheets S is corrected by the register roller pair 240. The position of the sheets S is detected by a line sensor 71a located upstream of the register roller pair 240, and the position of the electrostatic latent image formed on the photosensitive drum 212 is corrected according to the detected position of the sheets S. Note that the line sensor 71a or 71b and the control unit 401 together can also be referred to as a detection device located within the image forming apparatus 201.

[0023] After the sheet S is corrected for skew and the electrostatic latent image formed on the photosensitive drum 212 is corrected, the sheet S is transported to the secondary transfer section 201D by the register roller pair 240. In the secondary transfer section 201D, a secondary transfer bias is applied to the secondary transfer roller 217, and the image formed on the intermediate transfer belt 216 is transferred to the sheet S.

[0024] The sheet S on which the image has been secondarily transferred is transported to the fixing unit 201E. In the fixing unit 201E, the sheet S is subjected to heat and pressure in the nip section formed by the pressure roller 220a and the heating roller 220b, and the unfixed image secondarily transferred onto the sheet S is fixed. The sheet S with the fixed image is discharged into the discharge space V by the first discharge roller pair 225a or the second discharge roller pair 225b located downstream of the fixing unit 201E, and is loaded onto the paper output tray 223 in the discharge space V. If images are to be formed on both sides of the sheet S, after the image on the first side is fixed, the sheet S is transported to the re-transport passage R by the reversing roller pair 222 and transported again to the image forming unit 201B. During this transport, the position of the sheet S is detected by the line sensor 71b located in the re-transport passage R, and the formation position of the electrostatic latent image corresponding to the image on the second side formed on the photosensitive drum 212 is corrected according to the detected position of the sheet S.

[0025] (Schematic diagram showing the position of sheet S and line sensor) Figure 3 is a schematic diagram showing the position of the sheet S and the line sensor 71. The line sensor 71 is positioned in the width direction perpendicular to the conveying direction X of the sheet S and detects the edges of the sheet S in the width direction. The threshold range Y of the line sensor 71 is set according to the size of the sheet S. When both the sheet S and the line sensor 71 are normal, the sheet detection position Z is within the threshold range Y, and the sheet position is determined to be normal.

[0026] Figure 4 shows cases where the sheet detection position Z is not within the threshold range Y. Figure 4(a) shows the case where the sheet S is transported so that the sheet detection position Z is outside the threshold range Y. Figure 4(b) shows the case where the edge of the sheet S is bent, causing the sheet detection position Z to be outside the threshold range Y. Figure 4(c) shows the case where an image is formed on the sheet S, and the edge of the image is detected as the edge of the sheet S, causing the sheet detection position Z to be outside the threshold range Y. In all cases, the sheet position is determined to be abnormal.

[0027] (Block diagram for line sensor control) Referring to Figure 2, the control of line sensors 71a and 71b, and the control of the image formation position based on the outputs from line sensors 71a and 71b will be explained. The control unit 401 receives outputs from the register roller pair 240 and line sensors 71a and 71b, which are located on the re-transport path R, respectively. The control unit 401 also receives sheet size information 406 from the operation unit 730 and the printer driver.

[0028] The control unit 401 operates the line sensor power supply circuit 403 via the line sensor power supply control unit 402 to turn on or off the power to line sensors 71a and 71b. The control unit 401 also receives the signal from line sensor 71a or line sensor 71b via the CPU 404 and detects the position of the sheet S being transported. The image data correction unit 405 corrects the position of the image to be formed on the photosensitive drum 212 based on the detected position of the sheet S and the size information 406 of the sheet S.

[0029] (Flowchart showing a method for correcting the image formation position) Figure 5 is a flowchart showing the method for correcting the image formation position. In S101, the control unit 401 sets a threshold range Y for detecting the sheet S based on the sheet S size information 406 input via the operation unit 730 or the printer driver. In S102, the control unit 401 starts transporting the sheet S. In S103, the control unit 401 causes the line sensor 71a or line sensor 71b to detect the sheet S.

[0030] In S104, the control unit 401 determines the sheet detection position Z where sheet S was detected. In S105, the control unit 401 determines whether the sheet detection position Z is within the threshold range Y. If it is within the threshold range Y, the process proceeds to S106; otherwise, the process proceeds to S107.

[0031] In S106, the control unit 401 determines that the detection result for sheet S is normal. Then, based on the size information 406 of sheet S and the sheet position detection position Z, it calculates the correction amount for the image formation position. In S107, the control unit 401 determines that the detection result for sheet S is abnormal. Then, it determines the cause of the abnormality. Furthermore, the control unit 401 decides not to correct the image formation position and proceeds to S108. The method for determining the cause will be explained in detail in Figure 6. In S108, the control unit 401 starts the image formation operation.

[0032] (A flowchart showing how to identify the cause of the anomaly) Figure 6 is a flowchart illustrating the method for identifying the cause of the anomaly. Steps similar to those in Figure 5 are numbered as above, and their explanations are omitted here.

[0033] In S201, the control unit 401 sets counter N to 0. When counter N = 0, it indicates that no abnormality has occurred in the line sensor. In S105, the control unit 401 determines whether the sheet detection position Z is within the threshold range Y. If it is within the threshold range Y, the process proceeds to S202; otherwise, the process proceeds to S204.

[0034] If the value is within the threshold range Y, in S202 the control unit 401 determines whether counter N=0 or not. If counter N=0, proceed to S106. If counter N=0, proceed to S203. In S203, the control unit 401 determines that a temporary malfunction has occurred in the line sensor. Following S203, a warning message may be displayed on the operation unit 730 indicating that a temporary malfunction may have occurred in the line sensor.

[0035] If the threshold range Y is outside, in S204 the control unit 401 detects the sheet S within the entire detection area of ​​the line sensor 71a or 71b. In S205 the control unit 401 determines whether or not the sheet S was detected. If the sheet S is detected, proceed to S206; otherwise, proceed to S208.

[0036] If sheet S is detected, in S206 the control unit 401 determines that there is a transport error with sheet S. In S207 the control unit 401 displays a message on the operation unit 730 indicating that a transport error with sheet S has occurred.

[0037] If sheet S is not detected, in S208 the control unit 401 determines whether counter N=0 or not. If counter N=0, proceed to S209; otherwise, proceed to S212.

[0038] If counter N=0, in S209 the control unit 401 turns off the power to the line sensor. Then, in S210, the control unit 401 turns the power to the line sensor back on. In this way, if sheet S is not detected, there is a possibility of line sensor failure, so the power to the line sensor is restarted. For example, if the IC inside the sensor has latched up and sheet S cannot be detected, this power off / on operation will return the line sensor to a normal state and enable it to detect sheet S. In S211, the control unit 401 adds 1 to counter N. Then, returning to S103, the control unit 401 acquires the detection result from the line sensor again.

[0039] If counter N=0, in S212 the control unit 401 determines that a line sensor malfunction has occurred. This is because, even after turning the line sensor off and on in S209 and S210, the line sensor does not recover and remains unable to detect sheet S, thus indicating a malfunction. The control unit 401 then displays a message on the operation unit 730 indicating that a line sensor malfunction has occurred.

[0040] In this way, when the line sensor fails to properly detect sheet S, it is possible to determine whether the problem is due to sheet S or a malfunction of the line sensor. For example, even if the line sensor is functioning normally, if an image is formed on sheet S and an abnormal detection result occurs, it can be determined that the line sensor is functioning normally. Also, if the IC inside the sensor latches up due to discharge from a sheet with a high charge, such as a reused sheet or a sheet that has just been fixed, it can be restored by turning the line sensor off and on. Furthermore, if it does not recover even after turning the line sensor off and on, it can be determined that the line sensor is faulty.

[0041] In the copier market, there is a demand for minimizing downtime through service maintenance that addresses malfunctions. When a malfunction occurs, if the cause of the malfunction is unknown, service technicians have to guess the possible causes and take action, which is costly and time-consuming. However, in this embodiment, the cause of the malfunction can be identified, making it possible to take appropriate action based on the cause. [Examples]

[0042] In the previous embodiment 1, it was determined whether the edge of the sheet S was detected within the threshold range Y. In this embodiment, we will describe the case in which the position of the sheet S is detected without setting a threshold range. Note that components such as the image forming apparatus 201, which are the same as in the previous embodiment 1, are denoted by the same reference numerals, and detailed explanations are omitted here.

[0043] (A flowchart showing how to identify the cause of the anomaly) Figure 7 is a flowchart illustrating the method for identifying the cause of the anomaly. Steps similar to those in Figures 5 and 6 are numbered as above, and their explanations are omitted here.

[0044] In S301, the control unit 401 performs detection across the entire detection range of the line sensor. In S302, the control unit 401 determines whether or not sheet S is detected. If sheet S is detected, the process proceeds to S105; otherwise, the process proceeds to S208. The subsequent steps are the same as those described in Figure 6.

[0045] In this way, when the line sensor fails to properly detect sheet S, it is possible to determine whether the problem is due to sheet S or a malfunction of the line sensor. [Explanation of Symbols]

[0046] S Seat 201 Image forming apparatus 401 Control Unit

Claims

1. A detection means for detecting a sheet, The system includes a control means that detects the edge of the sheet in a direction perpendicular to the sheet transport direction based on the detection result of the aforementioned detection means, The detection device is characterized in that, when the control means determines that an abnormality has occurred based on the detection result of the detection means, it turns off the power to the detection means, turns on the power to the detection means, obtains a detection result from the detection means again, and if it determines that an abnormality has occurred again based on the newly obtained detection result, it determines that the detection means is the cause of the abnormality.

2. The detection device according to Claim 1, characterized in that the control means displays a first message indicating that the sheet is the cause when the control means determines that the sheet is the cause, and the detection means displays a second message indicating that the detection means is the cause when the detection means determines that the sheet is the cause.

3. The detection device according to claim 1, characterized in that the control means receives sheet size information and sets a threshold range in which the edge of the sheet is detected based on the size information.

4. The detection device according to claim 3, characterized in that the control means determines that the sheet is the cause of the abnormality when it determines that the position of the edge of the sheet based on the detection result of the detection means is not within the threshold range.

5. A conveying means for transporting sheets, Image forming means for forming an image on a sheet, An image forming apparatus comprising a detection device according to any one of claims 1 to 4.

Images