Image forming system, sensor deterioration determination method, and program

Abstract

To provide an image forming system, a sensor deterioration determination method and a program which make it possible to find a deteriorated optical sensor in an early stage while maintaining productivity.SOLUTION: An image forming system for forming an image on a conveyed recording medium comprises: a sensor for detecting light; a recording medium detection part for detecting the recording medium based on the detected light; and a control part for determining the deterioration of the sensor based on a detection result of the recording medium obtained by inputting a second input lower than a first input to the sensor when the recording medium is detected in a state where the first input is input to the sensor.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to an image forming system, a sensor deterioration determination method, and a program. [Background technology]

[0002] Conventionally, in an image forming apparatus that forms an image on a sheet of paper, which is a transported recording medium, an optical sensor is disposed on the transport path to detect the timing of transport of the sheet of paper and the leading and trailing ends of the sheet of paper. The optical sensor used in the image forming apparatus includes a light emitting element and a light receiving element, and detects reflected light of light emitted from the light emitting element with the light receiving element.

[0003] Optical sensors usually lose light emission due to aging. When the light emission decreases, the amount of reflected light decreases accordingly, and the amount of received light also decreases. As a result, the sensor is no longer able to properly detect paper, which is a recording medium.

[0004] Therefore, it has been proposed to increase the light emission amount when the light emission amount of the optical sensor decreases.For example, Patent Document 1 discloses an image forming device that calculates the degree of deterioration of the optical sensor and adjusts the light emission amount to an appropriate amount based on the calculation result, thereby extending the life of the optical sensor while ensuring the detection accuracy of the optical sensor. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2003-316217 A Summary of the Invention [Problem to be solved by the invention]

[0006] Recently, the use of white toner has increased in image forming devices, and colored paper such as black paper may be used. When black paper is used as the recording medium, the amount of reflected light received by the optical sensor is less than the amount of reflected light from white paper. Therefore, when detecting colored paper, the amount of light emitted or the light receiving sensitivity of the optical sensor is increased.

[0007] However, the paper detection accuracy of the deteriorated optical sensor is unstable, making it difficult to properly detect the paper. In addition, if the amount of light emitted is increased or the light receiving sensitivity of the optical sensor is increased as in the image forming apparatus described in Patent Document 1, false detection due to disturbance light occurs, affecting the quality of the formed image. Therefore, when using a deteriorated optical sensor to extend its life, it is difficult to properly ensure productivity in the case of colored paper such as black paper, due to variations in the position of the leading edge of the paper, front and back position accuracy, and reduced resist and paper consistency.

[0008] The present disclosure has been made in consideration of the problems in the above-described conventional technology, and aims to provide an image forming system, a sensor deterioration determination method, and a program that are capable of detecting degraded optical sensors early while maintaining productivity. [Means for solving the problem]

[0009] The image forming system according to the present disclosure includes: An image forming system for forming an image on a conveyed recording medium, A sensor that detects light; a recording medium detection unit that detects the recording medium based on the detected light; a control unit that, when the recording medium is detected in a state where a first input is input to the sensor, determines deterioration of the sensor based on a detection result of the recording medium obtained by inputting a second input to the sensor that is lower than the first input; Equipped with.

[0010] The sensor deterioration determination method according to the present disclosure includes: Detecting the recording medium being conveyed based on the light detected by the sensor; When the recording medium is detected while a first input is input to the sensor, deterioration of the sensor is determined based on the detection result of the recording medium obtained by inputting a second input to the sensor that is lower than the first input.

[0011] The program according to the present disclosure is The above-described sensor deterioration determination method is executed by a computer. Effect of the Invention

[0012] According to the present disclosure, deteriorated optical sensors can be detected early while maintaining productivity. [Brief description of the drawings]

[0013] [Figure 1] FIG. 1 is a schematic diagram showing an example of the configuration of an image forming system according to the first embodiment. [Diagram 2] FIG. 2 is a block diagram showing a main part of a control system of the image forming system according to the first embodiment. [Diagram 3] 3 is a functional block diagram showing an example of the configuration of a control unit in FIG. 2. [Figure 4] FIG. 4 is a timing chart for explaining the sensor deterioration determination process in the case where the transport sensor is not deteriorated. [Diagram 5] FIG. 5 is a timing chart for explaining the sensor deterioration determination process when the transport sensor is deteriorated. [Figure 6] FIG. 6 is a flowchart showing an example of the flow of the deterioration determination process performed by the image forming system according to the first embodiment. [Figure 7] FIG. 7 is a timing chart for explaining the sensor deterioration determination process in the case where the plurality of transport sensors are not deteriorated in the image forming system according to the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. The present disclosure is not limited to the following embodiments, and various modifications are possible without departing from the spirit of the present disclosure. In addition, in each drawing, the same reference numerals are used to denote the same or equivalent parts, and this is common throughout the entire specification.

[0015] <Embodiment 1> Hereinafter, a first embodiment of the present disclosure will be described with reference to the drawings. The image forming system according to the first embodiment is capable of forming an image on a paper (recording medium) such as a sheet of paper.

[0016] [Configuration of image forming system 1] Fig. 1 is a schematic diagram showing an example of the configuration of an image forming system 1 according to the present embodiment 1. Fig. 2 is a block diagram showing a main part of a control system of the image forming system 1 according to the present embodiment 1. As shown in Fig. 1, the image forming system 1 includes an image forming apparatus 100, a paper feed section 200, an image calibration control section 300, a post-processing section 400, and a paper discharge section 500.

[0017] The image forming apparatus 100 is an intermediate transfer type color image forming apparatus that utilizes electrophotographic process technology. That is, the image forming apparatus 100 primarily transfers the toner images of each color, CMYK, formed on a photoconductor onto an intermediate transfer body, and then superimposes the four color toner images on the intermediate transfer body, and then secondarily transfers them onto paper to form an image. CMYK stands for C (cyan), M (magenta), Y (yellow), and K (black).

[0018] The image forming apparatus 100 employs a tandem system in which photoconductors corresponding to the four colors, CMYK, are arranged in series in the running direction of an intermediate transfer body, and toner images of each color are transferred sequentially to the intermediate transfer body in a single step.

[0019] As shown in FIG. 2, the image forming system 1 includes an image processing unit 10, an image forming unit 20, a fixing unit 30, a paper transport unit 40, an operation display unit 50, a communication unit 71, a memory unit 72, a control unit 600, a paper feed unit 200, an image calibration control unit 300, a post-processing unit 400, a paper discharge unit 500, and a transport sensor 5, etc.

[0020] The image processing unit 10 includes a circuit for performing image processing on input image data according to initial settings or user settings, etc. The image forming unit 20 is controlled based on the image data that has been subjected to the image processing.

[0021] The image forming section 20 includes an image forming unit 21, an intermediate transfer unit 22, and a secondary transfer unit 23. The image forming unit 21 forms an image using color toners of each color component based on image data from the image processing section 10. For example, the image is formed using color toners of each color component of Y (yellow), M (magenta), C (cyan), and K (black).

[0022] The image forming unit 21 has, for each color, an exposure device, a developing device, a photosensitive drum, a charging device, a drum cleaning device, etc. Since known technologies can be adopted for the exposure device, the developing device, the photosensitive drum, the charging device, and the drum cleaning device, detailed description thereof will be omitted here.

[0023] The intermediate transfer unit 22 includes an intermediate transfer belt and the like. The intermediate transfer belt is stretched in a loop shape around a number of support rollers and travels in the direction of arrow A. The support rollers include a backup roller, a primary transfer roller, a drive roller, and other rollers, but these are not shown here. The intermediate transfer belt is pressed against the photosensitive drum, thereby transferring a toner image from the photosensitive drum to the intermediate transfer belt.

[0024] The intermediate transfer unit 22 may be configured to include a belt cleaning device having a plate-shaped belt cleaning blade or the like that is in sliding contact with the surface of the intermediate transfer belt. The belt cleaning device removes residual toner and the like that remains on the surface of the intermediate transfer belt after the secondary transfer.

[0025] The secondary transfer unit 23 includes a secondary transfer roller, etc. The secondary transfer roller is in pressure contact with the intermediate transfer belt, so that a secondary transfer nip is formed between the intermediate transfer belt and the secondary transfer roller.

[0026] In the secondary transfer unit 23, when the paper is transported to the secondary transfer nip, the toner images of each color carried on the intermediate transfer belt are transferred onto the paper at once. The paper onto which the toner images have been transferred is transported toward the fixing unit 30 by the secondary transfer roller.

[0027] Incidentally, the secondary transfer unit 23 may be a belt-type secondary transfer unit having a secondary transfer belt stretched around a plurality of support rollers, instead of a roller-type secondary transfer unit having a secondary transfer roller or the like.

[0028] The fixing unit 30 includes a fixing roller and a pressure roller. The fixing roller is heated to a predetermined fixing temperature, and the pressure roller forms a fixing nip between the fixing roller and the pressure roller to sandwich and transport the paper. In the fixing unit 30, the toner image is fixed to the paper by heating and pressurizing the paper, which has been secondarily transferred and transported, in the fixing nip.

[0029] The paper transport section 40 includes a transport path section 41. The transport path section 41 is composed of, for example, a path for transporting the paper, a plurality of transport rollers, and a drive motor for driving the transport rollers to rotate. The transport path section 41 transports the paper supplied from the paper feed section 200 to the secondary transfer unit 23 and the fixing section 30, and then transports the paper to the paper discharge section 500.

[0030] In the transport path section 41, a registration roller pair 41a is provided upstream of the secondary transfer unit 23 in the paper transport direction D. The registration roller pair 41a adjusts the transport timing and direction (angle) of the paper transported to the secondary transfer unit 23.

[0031] The operation display unit 50 is composed of, for example, a liquid crystal display (LCD) with a touch panel, and functions as a display unit and an operation unit. The display unit displays various operation screens, image status display, and operation status of each function according to a display control signal input from the control unit 600. The operation unit includes various operation keys such as a numeric keypad and a start key, and outputs operation signals to the control unit 600 upon receiving various input operations by the user.

[0032] Paper feed unit 200 is disposed upstream of image forming apparatus 100 in paper transport direction D, and is connected to image forming apparatus 100. Paper feed unit 200 has a plurality of paper feed trays 201, 202, and 203, and each of paper feed trays 201, 202, and 203 stores sheets of paper (standard paper or special paper) identified based on basis weight or size, etc., for each preset type. Based on an instruction from image forming apparatus 100, paper feed unit 200 supplies the specified paper to image forming apparatus 100.

[0033] The image calibration control unit (ICCU; Image Calibration Control Unit) 300 is disposed between the image forming apparatus 100 and the post-processing unit 400 in the paper conveying direction D, and is connected to the image forming apparatus 100 on the upstream side and to the post-processing unit 400 on the downstream side. The image calibration control unit 300 inspects and calibrates the image formed by the image forming apparatus 100. The image calibration control unit 300 also includes image sensors 301a and 301b such as CCDs (Charge Coupled Devices), and functions as a reading unit that reads the conveyed paper.

[0034] When the image calibration control unit 300 functions as a reading unit, the image sensor 301a is disposed above the paper transport path, facing the paper being transported, and configured to read the front (upper) side of the paper being transported. The image sensor 301b is disposed below the paper transport path, facing the paper being transported, and configured to read the back (lower) side of the paper being transported.

[0035] As the image sensors 301a and 301b, for example, a line sensor extending across a width equal to or greater than the width of the paper (width in a direction perpendicular to the paper transport direction D), such as a line scanner or a line sensor camera, is used.

[0036] Here, as an example, the image calibration control unit 300 is configured to have image sensors 301a and 301b that read both sides (front and back) of the paper, but is not limited to this and may be configured to have, for example, only image sensor 301a that reads one side (front side) of the paper.

[0037] The post-processing unit 400 is disposed between the image calibration control unit 300 and the paper discharge unit 500 in the paper transport direction D, and is connected to the image calibration control unit 300 on the upstream side and to the paper discharge unit 500 on the downstream side. The post-processing unit 400 performs a predetermined post-processing on the paper on which an image has been appropriately formed. For example, the post-processing unit 400 performs processes such as folding the paper, punching holes in the paper, gluing the paper, and cutting the paper.

[0038] The paper discharge unit 500 is disposed downstream of the image forming apparatus 100 in the paper transport direction D, and is connected to the image forming apparatus 100 via the image calibration control unit 300. The paper discharge unit 500 has a paper discharge tray 501 and a purge tray 502, and discharges paper transported from the image forming apparatus 100 to the paper discharge tray 501 or the purge tray 502.

[0039] The paper output tray 501 outputs paper on which an image has been formed by the image forming apparatus 100. The purge tray 502 outputs paper that does not satisfy a predetermined condition as a result of the image formed on the paper being read by the image calibration control unit 300. For example, if the formed image read by the image calibration control unit 300 does not satisfy a predetermined condition, the paper output unit 500 may output the paper on which the image has been poorly formed from the purge tray 502, as indicated by the dashed-dotted arrow in FIG.

[0040] In the present embodiment 1, one or more transport sensors 5 are disposed on the transport path of the image forming system 1. The transport sensor 5 may be disposed not only in the image forming apparatus 100 but also in any of the devices constituting the image forming system 1.

[0041] The transport sensor 5 is an optical sensor having a light emitting element and a light receiving element. The transport sensor 5 detects an object that reflects the light by irradiating a predetermined detection area with light from the light emitting element and receiving the reflected light of the irradiated light with the light receiving element. The transport sensor 5 converts the received light into an electrical signal according to the amount of light, and outputs it as a sensor output voltage.

[0042] It is not necessary for the transport sensor 5 to have a light emitting element. For example, the transport sensor 5 may be configured to receive light emitted from an external light source and reflected by an object.

[0043] The control unit 600 is connected to the above-mentioned image processing unit 10, image forming unit 20, fixing unit 30, paper transport unit 40, operation display unit 50, communication unit 71, memory unit 72, paper feed unit 200, image calibration control unit 300, post-processing unit 400, paper discharge unit 500, and transport sensor 5. The control unit 600 issues various instructions to each of these units and executes predetermined processes.

[0044] In the first embodiment, the control unit 600 performs a sensor deterioration determination process to determine deterioration of the transport sensor 5. The sensor deterioration determination process will be described later in detail.

[0045] The control unit 600 includes a CPU (Central Processing Unit) 601, a ROM (Read Only Memory) 602, and a RAM (Random Access Memory) 603. The CPU 601 reads out a program corresponding to the processing contents from the ROM 602, loads it in the RAM 603, and centrally controls the operation of each block of the image forming system 1 in cooperation with the loaded program. At this time, various data such as a LUT (Look Up Table) stored in the storage unit 72 is referenced. The storage unit 72 is configured, for example, with a non-volatile semiconductor memory (so-called flash memory) or a hard disk drive.

[0046] The control unit 600 transmits and receives various data to and from an external device (e.g., a personal computer) connected to a communication network such as a LAN (Local Area Network) or a WAN (Wide Area Network) via the communication unit 71. The control unit 600 receives, for example, image data transmitted from an external device, and forms an image on a sheet based on this image data (input image data). The communication unit 71 is formed, for example, of a communication control card such as a LAN card.

[0047] Fig. 3 is a functional block diagram showing an example of the configuration of the control unit 600 in Fig. 2. As shown in Fig. 3, the control unit 600 has a sensor information acquisition unit 611, a driving voltage setting unit 612, a recording medium detection unit 613, a sensor deterioration determination unit 614, and a counter 615.

[0048] The sensor information acquisition unit 611 acquires sensor information related to the transport sensor 5. In the first embodiment, the sensor information acquisition unit 611 acquires the sensor output voltage output from the transport sensor 5 as the sensor information.

[0049] The driving voltage setting unit 612 sets a driving voltage for driving the transport sensor 5. In the present embodiment 1, the driving voltage setting unit 612 sets the driving voltage of the transport sensor 5 at a predetermined timing based on an instruction from the control unit 600 during the sensor deterioration determination process.

[0050] The recording medium detection unit 613 detects the presence of paper, which is a recording medium, in the detection area of ​​the transport sensor 5. The recording medium is, for example, white paper such as a sheet of paper. Alternatively, black paper (black paper) that reflects a small amount of light can also be used as the recording medium. The recording medium detection unit 613 detects the presence of paper by comparing the sensor output voltage acquired by the sensor information acquisition unit 611 with a threshold value stored in the memory unit 72.

[0051] During the sensor deterioration determination process, the sensor deterioration determination unit 614 determines whether or not the transport sensor 5 has deteriorated. Specifically, the sensor deterioration determination unit 614 determines that the transport sensor 5 has deteriorated when the leading edge of the paper is detected by the recording medium detection unit 613 and the drive voltage of the transport sensor 5 is changed and no paper is detected.

[0052] Counter 615 measures time based on instructions from control unit 600. In the first embodiment, counter 615 measures the time from when the leading edge of a conveyed sheet is detected to when the trailing edge of the sheet is detected in the sensor deterioration determination process.

[0053] 2 stores various data and the like used by each unit of the control unit 600. For example, the storage unit 72 stores a threshold value for a sensor output voltage used by the recording medium detection unit 613.

[0054] [Operation of image forming system 1] In image forming system 1 according to the first embodiment having the above configuration, when an image is formed on paper, which is a recording medium, the paper is stored in paper feed trays 201, 202, and 203 of paper feed unit 200. The paper fed from paper feed unit 200 is then transported to image forming device 100, where an image is formed (hereinafter referred to as "printing"), and the paper is then transported to image calibration control unit 300.

[0055] The paper conveyed to the image calibration control unit 300 has the image formed on the paper and the paper size, etc., read, and is conveyed to the post-processing unit 400. The paper conveyed to the post-processing unit 400 is then subjected to predetermined post-processing such as cutting, and is conveyed to the paper discharge unit 500.

[0056] [Sensor deterioration determination process] The sensor deterioration determination process according to the first embodiment is normally performed at a predetermined timing during an image forming mode (printing mode) in which an image is formed on a recording medium.

[0057] Usually, in the image formation mode, the detection of the paper is performed by comparing the sensor output voltage output from the transport sensor 5 according to the amount of light received by the transport sensor 5 with a preset threshold value. At this time, the transport sensor 5 is driven by a predetermined drive voltage, and if the paper is properly detected, it means that the transport sensor 5 has not deteriorated and is operating normally. Therefore, if the paper can be properly detected, it is determined that the transport sensor 5 has not deteriorated. In other words, it is considered that the detection of deterioration of the transport sensor 5 is performed based on the detection result of the paper by the transport sensor 5, for example.

[0058] On the other hand, when the amount of light emitted by the transport sensor 5 decreases due to deterioration over time, the sensor output voltage output from the transport sensor 5 also decreases. When the deterioration of the transport sensor 5 progresses and the sensor output voltage falls below the threshold, the sensor 5 is no longer able to properly detect paper, and therefore the deterioration of the transport sensor 5 can be detected.

[0059] However, even if the transport sensor 5 deteriorates, if the deterioration is minor such that the sensor output voltage is equal to or greater than the threshold, the paper can be detected. Therefore, in this case, it is not possible to quickly determine that the transport sensor 5 has deteriorated.

[0060] Therefore, in the first embodiment, a sensor deterioration determination process is performed to quickly determine the deterioration of the transport sensor 5. The flow of the sensor deterioration determination process will be described below using a specific example.

[0061] (When the transport sensor 5 is not deteriorated) First, a case will be considered in which the transport sensor 5 is not deteriorated and operates normally. Fig. 4 is a timing chart for explaining the sensor deterioration determination process in the case in which the transport sensor 5 is not deteriorated.

[0062] Normally, the transport sensor 5 is driven by a driving voltage Va. The driving voltage Va is the amount of light reflected by the paper and received by the transport sensor 5. In the image forming system 1 according to the first embodiment, black paper (black paper) that reflects a small amount of light may be used as a recording medium, and the driving voltage Va is set to a voltage that provides a sufficient amount of reflected light even with such black paper.

[0063] At time t0, when the paper conveyed on the conveying path enters the detection area of ​​the conveying sensor 5, the conveying sensor 5 receives the light reflected from the paper, converts it into a sensor output voltage, which is an electrical signal, and outputs it. Then, based on the sensor output voltage, it is determined whether the paper has been detected. In this case, the sensor output voltage from the conveying sensor 5 is equal to or greater than a predetermined threshold, so the paper is detected. Here, the detection of the paper is determined when the paper enters the detection area of ​​the conveying sensor 5, and specifically, the leading edge of the paper is detected.

[0064] Next, when time T1 has elapsed from time t0 when the leading edge of the paper was detected, the transport sensor 5 is driven by drive voltage Vb. Drive voltage Vb is a voltage lower than drive voltage Va, and is the lowest voltage at which paper can be detected based on the light reflected from paper such as black paper that has little reflected light. Time T1 is a time shorter than the transport time required for the paper to pass through the detection area from its leading edge to its trailing edge, which is obtained based on the size of the paper being transported.

[0065] As the drive voltage of the transport sensor 5 decreases from Va to Vb, the amount of light emitted decreases, and the reflected light from the paper decreases. Therefore, the sensor output voltage from the transport sensor 5 decreases. However, in this example, even if the sensor output voltage decreases, the transport sensor 5 is driven at the drive voltage Vb, which is the minimum voltage at which the paper can be detected. Therefore, although the sensor output voltage is lower than when driven at the drive voltage Va, it remains above the threshold value.

[0066] Next, taking into consideration the response time of the transport sensor 5, it is determined whether or not a sheet is detected at the time T2 has elapsed since time t0. In this example, the transport sensor 5 is operating normally, and the sensor output voltage from the transport sensor 5 is equal to or greater than the threshold value, so it is determined that a sheet is detected.

[0067] Next, when time T3 has elapsed from time t0, the transport sensor 5 is driven by the drive voltage Va. Time T3 is a time obtained based on the paper size and transport time, and is a time before the rear end of the paper passes through the detection area.

[0068] At the point in time when time T3 has elapsed from time t0, it is determined whether or not the trailing edge of the paper has been detected based on the sensor output voltage output from the transport sensor 5. In this case, since the sensor output voltage is equal to or greater than the threshold value, it is determined that the trailing edge of the paper has been detected. Note that trailing edge information regarding the trailing edge of the paper when the trailing edge of the paper is detected is used, for example, in the image forming system 1 to determine whether a paper jam has occurred.

[0069] After that, when the trailing edge of the paper passes through the detection area at the time T4 has elapsed since time t0, the transport sensor 5 no longer receives the reflected light from the paper. Therefore, the sensor output voltage from the transport sensor 5 becomes 0, and it is determined that the paper is not detected.

[0070] (When the transport sensor 5 is deteriorated) Next, consider a case where the transport sensor 5 is deteriorated. Fig. 5 is a timing chart for explaining the sensor deterioration determination process when the transport sensor 5 is deteriorated.

[0071] Normally, the transport sensor 5 is driven by a drive voltage Va. At time t0, when a sheet transported on the transport path enters the detection area of ​​the transport sensor 5, the transport sensor 5 receives light reflected from the sheet, converts it into a sensor output voltage, which is an electrical signal, and outputs it. Then, based on the sensor output voltage, it is determined whether or not the sheet has been detected. In this case, the sensor output voltage from the transport sensor 5 is equal to or higher than a predetermined threshold value, so the leading edge of the sheet is detected.

[0072] Next, when time T1 has elapsed since time t0 when the leading edge of the paper was detected, the transport sensor 5 is driven with the drive voltage Vb. As the drive voltage of the transport sensor 5 drops from Va to Vb, the amount of light emitted drops, and the reflected light from the paper decreases. Therefore, the sensor output voltage from the transport sensor 5 drops.

[0073] When the transport sensor 5 is deteriorated, the amount of light emitted is lower than when the transport sensor 5 is operating normally, and the reflected light from the paper is also lower. As a result, the sensor output voltage is lower than when the transport sensor 5 is operating normally, and falls below the threshold value.

[0074] Next, at the time when time T2 has elapsed from time t0, it is determined whether or not a sheet is detected. In this example, the transport sensor 5 is deteriorated, and the sensor output voltage from the transport sensor 5 is less than the threshold value, so it is determined that a sheet is not detected. Therefore, at this time, it can be determined that the transport sensor 5 is deteriorated.

[0075] When it is determined that the transport sensor 5 is deteriorated in this manner, for example, a notice warning that the transport sensor 5 is deteriorated may be displayed on the operation display unit 50 or the like. This makes it possible to notify the user of the deterioration of the transport sensor 5, so that the user can quickly take measures such as replacing the sensor.

[0076] Next, at the point in time when time T3 has elapsed from time t0, the transport sensor 5 is driven by the drive voltage Va. In this case, since the transport sensor 5 is driven by the drive voltage Va, the sensor output voltage rises and becomes equal to or greater than the threshold value, and it is determined that the rear end of the paper has been detected.

[0077] After that, when the trailing edge of the paper passes through the detection area at the time T4 has elapsed since time t0, the transport sensor 5 no longer receives the reflected light from the paper. Therefore, the sensor output voltage from the transport sensor 5 becomes 0, and it is determined that the paper is not detected.

[0078] In this way, the drive voltage is changed from Va to Vb during the period from time t0 when the paper enters the detection area to time T4 when the trailing edge of the paper passes through the detection area, and if the paper is not detected with the drive voltage changed, deterioration of the transport sensor 5 is detected. This allows early detection of even minor deterioration where the paper can be detected even when the sensor output voltage drops when driven with the normal drive voltage.

[0079] (Processing flow) 6 is a flowchart showing an example of the flow of the deterioration determination process by the image forming system 1 according to the present embodiment 1. This flowchart shows the flow of the process performed by the control unit 600.

[0080] In step S1, the drive voltage setting unit 612 of the control unit 600 sets the drive voltage of the transport sensor 5 to Va. In step S2, the sensor information acquisition unit 611 acquires from the transport sensor 5 a sensor output voltage obtained based on the light received by the transport sensor 5.

[0081] In step S3, the recording medium detection unit 613 reads out a threshold value for the sensor output voltage from the storage unit 72, and compares the read out threshold value with the sensor output voltage acquired in step S2 to determine whether the leading edge of the conveyed paper has been detected. If the sensor output voltage is equal to or greater than the threshold value, the recording medium detection unit 613 determines that the leading edge of the paper has been detected (step S3: YES). Then, in step S4, the control unit 600 starts counting the time using the counter 615.

[0082] On the other hand, if the sensor output voltage is less than the threshold value, the recording medium detection unit 613 determines that the leading edge of the paper has not been detected (step S3: NO).Then, the process returns to step S2, and the processes of steps S2 and S3 are repeated until the leading edge of the paper is detected based on the sensor output voltage.

[0083] In step S5, the control unit 600 determines whether or not time T1 has elapsed based on the counting by the counter 615. If time T1 has elapsed (step S5: YES), the drive voltage setting unit 612 sets the drive voltage of the transport sensor 5 to Vb in step S6. On the other hand, if time T1 has not elapsed (step S5: NO), the process of step S5 is repeated until time T1 has elapsed.

[0084] In step S7, the control unit 600 determines whether or not time T2 has elapsed based on the counting by the counter 615. If time T2 has elapsed (step S7: YES), in step S8, the drive voltage setting unit 612 acquires from the transport sensor 5 a sensor output voltage obtained based on the light received by the transport sensor 5. On the other hand, if time T2 has not elapsed (step S7: NO), the process of step S7 is repeated until time T2 has elapsed.

[0085] In step S9, the recording medium detection unit 613 determines whether or not a sheet has been detected by comparing the sensor output voltage acquired in step S8 with a threshold value stored in the memory unit 72. If the sensor output voltage is equal to or greater than the threshold value, the recording medium detection unit 613 determines that a sheet has been detected (step S9: YES).

[0086] On the other hand, if the sensor output voltage is less than the threshold value, the recording medium detection unit 613 determines that no paper has been detected (step S9: NO). Then, in step S10, the sensor deterioration determination unit 614 determines that the transport sensor 5 has deteriorated. At this time, the control unit 600 may, for example, cause the operation display unit 50 or the like to display that the transport sensor 5 has deteriorated.

[0087] Next, in step S11, the control unit 600 determines whether or not time T3 has elapsed based on the counting by the counter 615. If time T3 has elapsed (step S11: YES), the drive voltage setting unit 612 sets the drive voltage of the transport sensor 5 to Va in step S12. On the other hand, if time T3 has not elapsed (step S11: NO), the process of step S11 is repeated until time T3 has elapsed.

[0088] Finally, in step S13, the control unit 600 resets the counter when the time T4 at which the trailing edge of the paper passes through the detection area of ​​the transport sensor 5 has elapsed.

[0089] As described above, in the image forming system 1 according to the first embodiment, when the transport sensor 5 is driven at the drive voltage Va to detect a sheet, the transport sensor 5 is driven at the drive voltage Vb lower than the drive voltage Va to determine deterioration of the transport sensor 5 based on the detection result of the sheet. This makes it possible to detect early even minor deterioration in which the transport sensor 5 can detect a sheet even if the sensor output voltage from the transport sensor 5 drops when driven at the normal drive voltage Va.

[0090] <Embodiment 2> Next, a second embodiment will be described. The second embodiment differs from the first embodiment in that the sensor deterioration determination process determines the deterioration of a plurality of transport sensors 5. In the second embodiment, the same reference numerals are used for the parts common to the first embodiment, and detailed description thereof will be omitted.

[0091] 7 is a timing chart for explaining the sensor deterioration determination process when the multiple transport sensors 5 are not deteriorated in the image forming system according to the second embodiment. In the following, a case will be described in which deterioration of two transport sensors 5A and 5B among the multiple transport sensors 5 arranged on the transport path of the image forming system 1 is determined. Also, each of the transport sensors 5A and 5B is assumed to share a driving voltage. Furthermore, the transport sensor 5A is assumed to be arranged upstream of the transport sensor 5B in the paper transport direction D on the transport path.

[0092] Normally, the transport sensors 5A and 5B are driven by a drive voltage Va. At time t0, when a sheet transported on the transport path enters the detection area of ​​the transport sensor 5A, the transport sensor 5A receives the light reflected from the sheet, converts it into a sensor output voltage, which is an electrical signal, and outputs it. Then, based on the sensor output voltage, it is determined whether the sheet has been detected. In this case, since the sensor output voltage from the transport sensor 5A is equal to or greater than a predetermined threshold, the leading edge of the sheet is detected. On the other hand, since the sheet has not entered the detection area of ​​the transport sensor 5B at time t0, the sheet is not detected.

[0093] Next, at the point in time T11 after time t0 when the leading edge of the paper is detected, the transport sensors 5A and 5B are driven with the drive voltage Vb. As the drive voltage of the transport sensor 5A drops from Va to Vb, the amount of light emitted drops, and the reflected light from the paper drops. Therefore, the sensor output voltage from the transport sensor 5A drops. However, even if the sensor output voltage drops, the transport sensor 5A is still driven with the drive voltage Vb, which is the minimum voltage at which the paper can be detected. Therefore, although the sensor output voltage drops compared to when the sensor is driven with the drive voltage Va, it remains above the threshold value.

[0094] Next, at the point when time T12 has passed from time t0, the transport sensor 5 is driven by the drive voltage Va. Here, the period from the point when time T11 has passed from time t0 to the point when time T12 has passed is the paper determination section by the transport sensor 5A, and the transport sensor 5A determines whether or not the paper has been detected. In this example, the transport sensor 5A is operating normally, and the sensor output voltage from the transport sensor 5A is equal to or greater than the threshold value, so it is determined that the paper has been detected.

[0095] Furthermore, at the point in time when time T12 has elapsed from time t0, it is determined whether or not the trailing edge of the paper has been detected based on the sensor output voltage output from the transport sensor 5A. In this case, since the sensor output voltage is equal to or greater than the threshold, the trailing edge of the paper is detected.

[0096] Furthermore, when time T13 has elapsed from time t0, when a sheet of paper enters the detection area of ​​the transport sensor 5B, which is disposed downstream of the transport sensor 5A, the transport sensor 5B receives light reflected from the sheet of paper, converts the received light into a sensor output voltage, and outputs the sensor output voltage. Then, based on the sensor output voltage, it is determined whether or not the sheet of paper has been detected. In this case, the sensor output voltage from the transport sensor 5B is equal to or greater than a predetermined threshold, so the leading edge of the sheet of paper is detected.

[0097] Furthermore, when the trailing edge of the paper passes through the detection area of ​​the transport sensor 5A at the point in time T14 after time t0, the transport sensor 5A no longer receives reflected light from the paper, and therefore the sensor output voltage from the transport sensor 5A becomes 0, and it is determined that the paper is not detected.

[0098] Next, at the point in time when time T15 has elapsed from time t0, the transport sensors 5A and 5B are driven by the drive voltage Vb. As the drive voltage of the transport sensor 5B drops from Va to Vb, the amount of light emitted drops, and the reflected light from the paper drops. Therefore, the sensor output voltage from the transport sensor 5B drops. However, even if the sensor output voltage drops, the transport sensor 5B is still driven by the drive voltage Vb, which is the minimum voltage at which the paper can be detected. Therefore, although the sensor output voltage drops compared to when it is driven by the drive voltage Va, it remains above the threshold value.

[0099] Next, at the point when time T16 has elapsed from time t0, the transport sensors 5A and 5B are driven by the drive voltage Va. Here, the period from the point when time T15 has elapsed from time t0 to the point when time T16 has elapsed is the paper determination section by the transport sensor 5B, and it is determined whether or not the paper has been detected by the transport sensor 5B. In this example, the transport sensor 5B is operating normally, and the sensor output voltage from the transport sensor 5B is equal to or greater than the threshold value, so it is determined that the paper has been detected.

[0100] Furthermore, at the point in time when time T16 has elapsed from time t0, it is determined whether or not the trailing edge of the paper has been detected based on the sensor output voltage output from the transport sensor 5B. In this case, since the sensor output voltage is equal to or greater than the threshold, the trailing edge of the paper is detected.

[0101] When the trailing edge of the paper passes through the detection area of ​​the transport sensor 5B after the time T17 has elapsed from the time t0, the transport sensor 5B no longer receives the reflected light from the paper, and therefore the sensor output voltage from the transport sensor 5B becomes 0, and it is determined that the paper is not detected.

[0102] In this way, even if multiple transport sensors 5 share the same drive voltage, deterioration of each transport sensor 5 can be discovered early based on the detection results in response to changes in the drive voltage for each transport sensor 5.

[0103] Although the first and second embodiments have been described above, the present disclosure is not limited to the above-described first and second embodiments, and various modifications and applications are possible within the scope of the gist of the present disclosure. For example, in the first and second embodiments, the sensor deterioration determination process has been described as being performed during a normal image formation mode (print mode), but this is not limiting, and may be performed during a determination mode for determining deterioration of the transport sensor 5, for example.

[0104] Specifically, in the dedicated mode, one sheet of reference paper, which is a reference recording medium, is conveyed to determine the deterioration of the conveyance sensor 5. At this time, the drive voltage Vb is set to a voltage that matches the characteristics of this reference paper. In other words, the drive voltage Vb is set to the minimum voltage at which the conveyance sensor 5 can detect the reference paper in a non-deteriorated state. This allows a deteriorated conveyance sensor 5 to be found early and efficiently, just like in the print mode.

[0105] In the first and second embodiments, the sensor deterioration determination process is performed by changing the drive voltage of the transport sensor 5, but the present invention is not limited to this. For example, the sensor deterioration determination process may be performed by changing the light receiving sensitivity of the transport sensor 5. In this case, instead of changing the drive voltage from Va to Vb, the control unit 600 changes the light receiving sensitivity of the transport sensor 5 from a predetermined sensitivity to a sensitivity lower than the predetermined sensitivity. This also makes it possible to find a deteriorated transport sensor 5 early.

[0106] Furthermore, in the first and second embodiments, the image forming system 1 is configured to include the image calibration control unit 300 and the post-processing unit 400, but the configuration of the image forming system 1 is not limited to this example. For example, the image forming system 1 may be configured to not include one or both of the image calibration control unit 300 and the post-processing unit 400. [Explanation of symbols]

[0107] 1. Image forming system 5 Transport Sensor 40 Paper transport section 41 Conveying path section 50 Operation display section 71 Communications Department 72 Memory section 100 Image forming device 200 Paper feed section 300 Image calibration control section 400 Post-processing section 500 Paper output section 600 Control section 601 CPU 602 ROM 603 RAM 611 Sensor information acquisition unit 612 Drive voltage setting unit 613 Recording medium detection unit 614 Sensor Deterioration Judgment Unit 615 Counter

Claims

1. An image forming system for forming an image on a conveyed recording medium, A sensor that detects light; a recording medium detection unit that detects the recording medium based on the detected light; a control unit that, when the recording medium is detected in a state where a first input is input to the sensor, determines deterioration of the sensor based on a detection result of the recording medium obtained by inputting a second input to the sensor that is lower than the first input; Equipped Image forming system.

2. The control unit is When the recording medium is not detected in a state where the second input is input to the sensor, it is determined that the sensor is deteriorated. The image forming system according to claim 1 .

3. The recording medium detection unit includes: The recording medium is detected when the amount of light detected is equal to or greater than a predetermined threshold value. The image forming system according to claim 1 .

4. Further comprising a light source that emits light according to a driving voltage; The control unit is When the recording medium is detected in a state where the light source is driven at a first driving voltage, deterioration of the sensor is determined based on a detection result of the recording medium obtained by driving the light source at a second driving voltage lower than the first driving voltage. The image forming system according to claim 1 .

5. The control unit is If the recording medium is not detected in a state in which the light source is driven with the second driving voltage, it is determined that the sensor is deteriorated. The image forming system according to claim 4 .

6. The control unit is When a predetermined time has elapsed since the recording medium was detected, the driving voltage is changed from the second driving voltage to the first driving voltage. The image forming system according to claim 4 .

7. The light source is The sensor includes The image forming system according to claim 4 .

8. The control unit is When the recording medium is detected with the light receiving sensitivity of the sensor set to a first light receiving sensitivity, deterioration of the sensor is determined based on a detection result of the recording medium obtained with the light receiving sensitivity set to a second light receiving sensitivity lower than the first light receiving sensitivity. The image forming system according to claim 1 .

9. The control unit is If the recording medium is not detected with the light receiving sensitivity set to the second light receiving sensitivity, it is determined that the sensor is deteriorated. The image forming system according to claim 8.

10. The control unit is When a predetermined time has elapsed since the recording medium was detected, the light sensitivity is changed from the second light sensitivity to the first light sensitivity. The image forming system according to claim 8.

11. A plurality of the sensors are provided, The control unit is Determining deterioration of the plurality of sensors The image forming system according to claim 1 .

12. The control unit is After determining deterioration of the sensor on the upstream side in the transport direction of the recording medium, the first input is input to the plurality of sensors before the recording medium is detected by the sensor on the downstream side. The imaging system of claim 11.

13. The recording medium is Paper containing colored paper with a lower reflectance than white The image forming system according to claim 1 .

14. A determination mode for determining deterioration of the sensor. The image forming system according to claim 1 .

15. Detecting the recording medium being conveyed based on the light detected by the sensor; When the recording medium is detected in a state where a first input is input to the sensor, deterioration of the sensor is determined based on a detection result of the recording medium obtained by inputting a second input to the sensor that is lower than the first input. A method for determining sensor deterioration.

16. A program for causing a computer to execute the sensor deterioration determination method according to claim 15.

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