Detector and image formation device

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 technology]

[0002] Conventionally, in an image forming apparatus, as shown in Patent Document 1, a method is known in which a sensor detects the inclination of a sheet being conveyed and corrects the relative positional relationship between the sheet and an image to be formed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2012-3174 Summary of the Invention [Problem to be solved by the invention]

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

[0005] The invention of the present application has been made in view of the above circumstances, and aims to provide a device that can determine the cause of an abnormality. [Means for solving the problem]

[0006] In order to achieve the above object, the device is provided with a detection means for detecting a sheet, and a control means for detecting the edge of the sheet in a direction perpendicular to the sheet conveying direction based on the detection result of the detection means, and 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, then turns on the power to the detection means, and obtains the detection result from the detection means again, thereby determining whether the abnormality is caused by the sheet or the detection means. [Effects of the Invention]

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

[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 seat position and line sensor [Figure 4] Schematic diagram showing the seat position and line sensor [Figure 5] Flowchart showing a method for correcting an image forming position [Figure 6] Flowchart showing how to determine the cause of an abnormality [Figure 7] Flowchart showing how to determine the cause of an abnormality DETAILED DESCRIPTION OF THE INVENTION

[0009] The following describes embodiments of the present invention with reference to the drawings. Note that the following embodiments do not limit the scope of the invention as claimed, and not all of the combinations of features described in the embodiments are necessarily essential to the solution of the invention. [Example]

[0010] (Image forming device) Fig. 1 is a schematic diagram of an image forming apparatus 201. Fig. 2 is a control block diagram of the image forming apparatus 201. The operation of the image forming apparatus 201 will be described with reference to Figs.

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

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

[0013] The image forming apparatus main body 201A includes an image forming unit 201B that forms an image on a sheet. An image reading device 202 is disposed above the image forming apparatus main body 201A and is substantially horizontal to the image forming apparatus main body 201A. A discharge space V for discharging sheets is formed between the image reading device 202 and the image forming apparatus main body 201A.

[0014] The cassette feeding section 230 includes a feeding cassette 1 for stacking sheets S, and a pickup roller 2 for feeding the sheets S stacked in the feeding cassette 1. The cassette feeding section 230 also includes a separation section including a feed roller 3 and a retard roller 4 for separating the sheets S sent out from the pickup roller 2.

[0015] The manual feed section 235 includes a manual feed tray 5 on which sheets S are stacked, and a pickup roller 502 that feeds the sheets S stacked on the manual feed tray 5. The manual feed section 235 also includes a separation section that includes a feed roller 503 and a retard roller 504 that separate the sheets S sent out from the pickup roller 502.

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

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

[0018] A fixing unit 201E is disposed above the secondary transfer roller 217, and a first pair of discharge rollers 225a, a second pair of discharge rollers 225b, and a double-sided reversing unit 201F are disposed above the fixing unit 201E. The double-sided reversing unit 201F is provided with a pair of reversing rollers 222 that can rotate forward and backward, and a re-conveying path R that conveys the sheet S, on whose first side an image has been formed, again to the image forming unit 201B.

[0019] An operation unit 730 serving as a means for accepting operations from a user is provided on the top of the image forming apparatus 201. The operation panel is a touch panel type that not only displays information but also allows input.

[0020] (Operation of image forming device) 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 subjected to image processing, 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, the surface of which has been 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 drum of each process cartridge 211, respectively.

[0021] The electrostatic latent images formed on the photosensitive drums 212 are developed by the developers 214 of each color to be visualized as images. The images formed on each photosensitive drum are transferred onto the intermediate transfer belt 216 in a superimposed manner by applying a primary transfer bias to the primary transfer rollers 219. As a result, a color image is formed on the intermediate transfer belt 216.

[0022] In parallel with the image forming operation, sheets S are conveyed one by one to a pair of registration rollers 240 by a cassette feeding unit 230 or a manual paper feeding unit 235. Skew of the sheets S is corrected by the pair of registration rollers 240. The position of the sheet S is detected by a line sensor 71a disposed upstream of the pair of registration rollers 240, and the position of the electrostatic latent image formed on the photosensitive drum 212 is corrected in accordance with the detected position of the sheet S. The line sensor 71a or 71b and the control unit 401 can also be collectively referred to as a detection device disposed within the image forming apparatus 201.

[0023] After the skew of the sheet S and the electrostatic latent image formed on the photosensitive drum 212 are corrected, the sheet S is conveyed to the secondary transfer section 201D by the pair of registration rollers 240. In the secondary transfer section 201D, a secondary transfer bias is applied to the secondary transfer roller 217, so that the image formed on the intermediate transfer belt 216 is secondarily transferred onto the sheet S.

[0024] The sheet S onto which the image has been secondarily transferred is transported to the fixing unit 201E. The sheet S is subjected to heat and pressure in a nip formed by a pressure roller 220a and a heating roller 220b in the fixing unit 201E, whereby the unfixed image that has been secondarily transferred onto the sheet S is fixed. The sheet S onto which the image has been fixed is discharged to a discharge space V by a first discharge roller pair 225a or a second discharge roller pair 225b provided downstream of the fixing unit 201E, and is stacked on a paper discharge tray 223 in the discharge space V. When 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 a re-conveyance path R by a 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 a line sensor 71b arranged on the re-conveyance path R, and the formation position of an electrostatic latent image corresponding to the image on the second side that is formed on the photosensitive drum 212 is corrected in accordance with the detected position of the sheet S.

[0025] (Schematic diagram showing the position of the sheet S and the line sensor) 3 is a schematic diagram showing the position of the sheet S and the line sensor 71. The line sensor 71 is arranged in the width direction perpendicular to the conveying direction X of the sheet S, and detects the edge of the sheet S in the width direction. A threshold range Y is set for the line sensor 71 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] FIG. 4 is a diagram showing a case where the sheet detection position Z is not located within the threshold range Y. FIG. 4(a) shows a case where the sheet S is transported so that the sheet detection position Z is outside the threshold range Y. FIG. 4(b) shows a case where the edge of the sheet S is folded, causing the sheet detection position Z to be outside the threshold range Y. FIG. 4(c) shows a 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 either case, the sheet position is determined to be abnormal.

[0027] (Block diagram for line sensor control) 2, the control of the line sensors 71a and 71b and the control of the image forming position based on the outputs from the line sensors 71a and 71b will be described. The control unit 401 receives outputs from the line sensors 71a and 71b, which are respectively arranged on the registration roller pair 240 and the re-conveyance path R. The control unit 401 also receives size information 406 of the sheet S from the operation unit 730 or 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 the line sensors 71a and 71b. The control unit 401 also receives the signal from the line sensor 71a or the signal from the line sensor 71b via the CPU 404 and detects the position of the sheet S being conveyed. The image data correction unit 405 corrects the formation position of the image to be formed on the photosensitive drum 212 based on the result of detecting the position of the sheet S and size information 406 of the sheet S.

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

[0030] In S104, the control unit 401 determines the sheet detection position Z at which the sheet S is 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, and if it is outside the threshold range Y, the process proceeds to S107.

[0031] In S106, the control unit 401 determines that the detection result of the sheet S is normal. Then, based on the size information 406 of the sheet S and the sheet position detection position Z, the amount of correction for the image forming position is calculated. In S107, the control unit 401 determines that the detection result of the sheet S is abnormal. Then, the control unit 401 determines the cause of the abnormality. Furthermore, the control unit 401 determines that the image forming position will not be corrected, and the process proceeds to S108. Note that the method for determining the cause will be explained in detail with reference to FIG. 6. In S108, the control unit 401 starts the image forming operation.

[0032] (Flowchart showing how to determine the cause of an abnormality) Fig. 6 is a flowchart showing a method for determining the cause of an abnormality. Note that the same steps as those in Fig. 5 above are given the same numbers, and their explanation will be omitted here.

[0033] In S201, the control unit 401 sets a counter N to 0. If the 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, and if it is outside the threshold range Y, the process proceeds to S204.

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

[0035] If it is outside the threshold range Y, 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 the sheet S has been detected. If the sheet S has been detected, the process proceeds to S206, and if it has not been detected, the process proceeds to S208.

[0036] If the sheet S is detected, in S206 the control unit 401 determines that there is an abnormality in the transport of the sheet S. In S207, the control unit 401 causes the operation unit 730 to display a message indicating that an abnormality in the transport of the sheet S has occurred.

[0037] If the sheet S is not detected, in S208, the control unit 401 determines whether the counter N is 0. If the counter N is 0, the process proceeds to S209, and if not, the process proceeds to S212.

[0038] If counter N=0, in S209, the control unit 401 turns off the power to the line sensor. Thereafter, in S210, the control unit 401 turns on the power to the line sensor again. In this way, if sheet S is not detected, there is a possibility that the line sensor is broken, so the power to the line sensor is once restarted. For example, if an IC in the sensor has latched up and is unable to detect sheet S, this power off / on operation will return the line sensor to a normal state, making it possible to detect sheet S. In S211, the control unit 401 adds 1 to counter N. Then, the process returns to S103, and the control unit 401 acquires the detection result from the line sensor again.

[0039] If counter N is not 0, in S212, the control unit 401 determines that a malfunction has occurred in the line sensor. This is because even though the line sensor was turned off and on in S209 and S210, the line sensor did not return to normal and remains in a state where it cannot detect sheet S, so it is determined that a malfunction has occurred. The control unit 401 causes the operation unit 730 to display a message indicating that an abnormality has occurred in the line sensor.

[0040] In this way, if the line sensor is unable to detect sheet S properly, it can be determined whether the problem is due to the sheet S or a malfunction of the line sensor. For example, even if the line sensor is operating normally, if an image is formed on sheet S and an abnormality occurs in the detection results, it can be determined that the line sensor is normal. Also, if the IC in the sensor latches up due to discharge from a highly charged sheet, such as a reused sheet or a sheet immediately after fixing, it can be restored by turning the line sensor off and on. Also, if the problem is not resolved by turning the line sensor off and on, it can be determined that the line sensor is malfunctioning.

[0041] In the copier market, there is a demand for reducing downtime through service maintenance to address abnormalities. When an abnormality occurs, if the cause of the abnormality is unknown, the service technician must guess possible causes and respond, which is costly and time-consuming. However, in this embodiment, the cause of the failure can be identified, making it possible to take appropriate action. [Example]

[0042] In the previous first embodiment, it was determined whether the edge of the sheet S was detected within the threshold range Y. In this embodiment, a case will be described in which the threshold range is not set and the position of the sheet S is detected. Note that the same reference numerals are used for the same components as in the previous first embodiment, such as the image forming apparatus 201, and detailed description thereof will be omitted here.

[0043] (Flowchart showing how to determine the cause of an abnormality) Fig. 7 is a flowchart showing a method for determining the cause of an abnormality. Note that the same steps as those in Fig. 5 and Fig. 6 are given the same numbers, and their explanation will be omitted here.

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

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

[0046] S seat 201 Image forming device 401 Control Unit

Claims

1. a detection means for detecting a sheet; a control unit that detects an edge of the sheet in a direction perpendicular to the sheet conveying direction based on the detection result of the detection unit, When the control means determines that an abnormality has occurred based on the detection results of the detection means, the control means turns off the power to the detection means, then turns on the power to the detection means, and obtains the detection results from the detection means again, thereby determining whether the abnormality is caused by the sheet or the detection means.

2. 2. The detection device according to claim 1, further comprising a display means for displaying a first message indicating that the sheet is the cause of the abnormality if it is determined that the sheet is the cause, and for displaying a second message indicating that the detection means is the cause of the abnormality if it is determined that the detection means is the cause of the abnormality.

3. 2. The detection device according to claim 1, wherein the control means, when determining that an abnormality has occurred again based on the detection result acquired again, determines that the abnormality is caused by the detection means.

4. 2. The detection device according to claim 1, wherein the control means receives sheet size information and sets a threshold range for detecting the edge of the sheet based on the size information.

5. The detection device according to claim 4, characterized in that the control means determines that the abnormality is caused by the sheet 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.

6. a conveying means for conveying a sheet; an image forming means for forming an image on a sheet; An image forming apparatus comprising: the detection device according to claim 1 .

Images