JP2020075779A - Image forming device - Google Patents

Abstract

To suppress erroneous setting due to influence of jammed paper even when replaced with a different kind of sensors.SOLUTION: An image forming device 100 includes a conveying roller R10 for conveying a sheet along a conveying path, laser scanners 1Y, 1M 1C and 1Bk for forming images on the sheet, a sheet detection sensor PS9 having a light emitting element 233 and a light receiving element 234 to detect the sheet based on a light-receiving result of the light receiving element 234 while pulse-lighting the light emitting element 233, and a CPU 301 for controlling conveyance of the sheet from a detection result of the sheet detection sensor PS9 based on an output logic table. The CPU 301 causes the conveying roller R10 to convey the sheet, acquires the light-receiving result of the light receiving element 234, sets the output logic table based on the light-receiving result, and determines that the other sheets stay when the light-receiving result changes out of a predetermined time range after starting the conveyance of the sheet.SELECTED DRAWING: Figure 7

Description

  The present invention relates to an image forming apparatus having a sensor that detects a conveyed sheet.

  Conventionally, an image forming apparatus feeds a sheet from a cassette or a tray, conveys the sheet along a conveyance path, and transfers a toner image to the conveyed sheet to create a product. If the sheet cannot be conveyed with high accuracy, an image is not formed at a desired position on the sheet, and the quality of the product is deteriorated. Further, when a jam occurs in the device, the sheet may be deformed into a bellows shape. It takes a lot of effort to remove the jam sheet that has been transformed into a bellows shape. Since it takes time to remove the jammed sheet, downtime during which printing cannot be performed may be lengthened.

  Therefore, a general image forming apparatus has a plurality of sheet detection sensors arranged in the conveyance path. Then, the image forming apparatus stops the conveyance of the sheet unless the sheet detection sensor detects the sheet at a predetermined timing. By controlling in this way, it is possible to prevent the downtime from becoming long.

  For example, Patent Document 1 discloses an image forming apparatus including a reflection type optical sensor in a conveyance path. Since a reflective optical sensor has a high responsiveness, it is possible to detect the presence or absence of a sheet with high accuracy even when the image forming apparatus is speeded up.

JP, 2003-306256, A

  The optical sensor to which the image forming apparatus can be attached has a similar appearance. Therefore, even different types of optical sensors can be attached to the image forming apparatus. Further, if an optical sensor to be attached to the image forming apparatus can be selected from different types of optical sensors, the degree of freedom in design can be increased, which is also advantageous for the manufacturer of the image forming apparatus. However, these optical sensors often have different optical characteristics even though they have similar appearances. Therefore, when the optical sensor attached to the image forming apparatus is replaced with an optical sensor of a different type, it is necessary to set parameters suitable for the optical sensor after the replacement.

  As a method for the device to reset the output logic, it is conceivable to acquire the output logic of the sensor without the seat. However, there is a possibility that the state without a sheet cannot be reliably ensured. For example, sensor replacement work by a service person is performed in a state where the device does not operate due to a sensor failure. At that time, there is a high possibility that jammed paper (staked paper) due to the sensor failure exists in the apparatus. When jammed paper (retained paper) is present in the apparatus, if the output logic setting described above is executed after the sensor is replaced, the output logic of the sensor on the retained paper may be erroneously set.

  In view of such circumstances, an object of the present invention is to prevent erroneous setting due to the influence of jammed paper even when the sensor is replaced with a different type.

  In order to solve the above problems, an image forming apparatus of the present invention includes a conveying unit that conveys a sheet along a conveying path, an image forming unit that forms an image on the sheet, and a light emitting unit that emits light to the conveying path. An optical sensor that has a light receiving unit that receives the reflected light from the sheet that is conveyed on the conveying path, and that detects the sheet based on the light receiving result of the light receiving unit; and the detection of the optical sensor based on a determination condition. From the result, a control unit that controls the conveyance of the sheet by the conveyance unit and a setting that causes the conveyance unit to convey the sheet, acquires the detection result of the optical sensor, and sets the determination condition based on the detection result Means and the setting means, if the detection result of the optical sensor changes outside a predetermined time range after the sheet starts to be conveyed, it is determined that another sheet is staying in the conveying path. And means.

  According to the present invention, erroneous setting due to the effect of jammed paper can be suppressed even when a sensor of a different type is replaced.

Cross-sectional view of image forming apparatus Sheet detection sensor configuration diagram Configuration diagram of control unit Output logic table of sheet detection sensor Output timing chart of PS9 and PS10 during output logic setting processing Output logic change storage table during output logic setting processing Output logic setting process flow by CPU 301

(First embodiment)
Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic sectional view of a color digital printer as an example of the image forming apparatus 100 of the present invention.

  First, the image forming unit will be described. The four laser scanners 1Y, 1M, 1C, and 1Bk form electrostatic latent images on the four photosensitive drums 2Y, 2M, 2C, and 2Bk, respectively, and toner images are formed by the four developing units 3Y, 3M, 3C, and 3Bk, respectively. To do. The respective color toner images formed on the four photosensitive drums 2Y, 2M, 2C and 2Bk are transferred onto the intermediate transfer belt 130 by the four primary transfer portions 4Y, 4M, 4C and 4Bk. As a result, a full-color toner image is formed on the intermediate transfer belt 130. The toner image on the intermediate transfer belt 130 is conveyed to the secondary transfer portion R11 by the rotation of the intermediate transfer belt 130.

  The sheet is fed from one of the cassettes CST1 to CST3 by the pickup units PU1 to PU3, and is transported by the transport roller pairs R5 to R9 toward the registration roller pair R10. Further, even when the sheet is fed from the manual feed tray MF, the fed sheet is conveyed to the registration roller pair R10.

  The registration roller pair R10 controls the sheet feeding timing so that the toner image on the intermediate transfer belt 130 is transferred to the target position of the sheet. The registration roller pair R10 may be configured to control the sheet conveyance speed instead of the conveyance timing. The toner image is transferred onto the sheet by the secondary transfer portion R11. After that, the sheet on which the toner image is transferred is conveyed to the fixing device UN3. The fixing unit UN3 heats and presses the toner image on the sheet to fix the toner image on the sheet. The sheet on which the image has been fixed is uncurled by the decurling unit UN5 from the reverse discharge unit UN4 and then discharged from the roller pair R15 to the outside of the apparatus main body. Further, after the first side is printed during double-sided printing, it is fed again to the registration unit UN1 from the reverse discharge unit UN4, the double-sided reverse unit UN6, and the double-sided transport path UN8, and similarly printed and discharged.

  Sheet detection sensors PS1 to PS23 for detecting the presence / absence of the sheet are arranged on the conveyance path along which the sheet is conveyed. The sheet detection sensors PS1 to PS23 are reflection type optical sensors.

  FIGS. 2A and 2B are a circuit block diagram of the sheet detection sensor and a diagram showing an input unit of the detection output of the sheet detection sensor. Light from the light emitting unit 201 configured by an LED or the like is reflected by the sheet that is the detection target, and the reflected light is received by the light receiving unit 202. The output units 203a and 203b output detection values corresponding to the light reception result of the light receiving unit 202. A high frequency component is removed by the CR filter from the detection value input unit 211 and is input to the control unit 300.

  FIG. 3 is a control block diagram of the image forming apparatus 100. The control unit 300 includes a CPU 301, an EEPROM 302, a RAM 303, an input / output unit 304, and an operation unit 305.

  The CPU 301 controls various sensors and motors and executes arithmetic processing based on a program stored in advance in the internal memory. The EEPROM 302 is a non-volatile memory of the image forming apparatus 100. Further, the types of the sheet detection sensors PS1 to PS23 are stored in the register of the EEPROM 302. The RAM 303 functions as a system work memory. The input / output unit 304 has an input circuit that receives signals from the sheet detection sensors PS1 to PS23 and a drive circuit that drives the motors M1 to M11 that drive the conveyance rollers. The CPU 301 controls the conveyance of the sheet by controlling the drive circuit based on the detection results of the sheet detection sensors PS1 to PS23. The operation unit 305 gives an instruction to start or stop the print settings of the image forming apparatus and the print operation. Further, the operation unit 305 is provided with a button for instructing execution of discrimination control of the sheet detection sensor described later.

  The sheet detection sensor PS1 outputs a high-level signal (a signal indicating a detection result) to the control unit 300 when detecting a sheet. The same applies to the sheet detection sensors PS2 to PS23. The output logic of the sheet detection sensors PS1 to PS23 of the present embodiment is not limited to the configuration in which a High level signal is output when a sheet is detected. For example, when the sheet detection sensor PS1 detects a sheet, a low level signal (a signal indicating the detection result) may be output to the control unit 300.

  In general, an optical sheet detection sensor may have a different output signal logic when a detection target is detected. However, the sensors commercialized by each sensor manufacturer are sold with similar mounting shapes and sizes. Therefore, in the sheet detection sensors (PS1 to PS23) used in the product, there is a demand for mounting sheet detection sensors having different output logics (hereinafter, alternative connection) for stable supply of parts and cost reduction. is there. When the output logics of the sensor before replacement and the sensor after replacement are the same, it is not necessary to change the determination logic of the control unit 300 that controls the sheet conveyance. However, when the output logic of the sensor after replacement is different from the output logic of the sensor before replacement, it is necessary to change the determination logic of the control unit 300 that controls the sheet conveyance.

  Hereinafter, the sheet detection sensors PS9 and PS10 will be described as a configuration that can be replaced with the sheet detection sensors having different output logics. Therefore, in order to normally execute the printing operation and the paper jam determination, the control unit 300 needs to recognize which output logic sensor is installed and set the processing program according to the output logic. .. The output logic of the sheet detection sensors (PS1 to PS23) is set by storing the output logic of the sheet detection sensor corresponding to when there is no paper in the predetermined memory area 1 of the RAM 303. Note that FIG. 4 shows output logic determination conditions (hereinafter, output logic table) corresponding to PS1 to PS23.

  Next, a specific method for creating the output logical table will be described. The control unit 300 can execute an operation mode (hereinafter, output logic setting process) for creating an output logic table, in addition to a function such as a printing operation. The output logic setting process is executed by inputting a command from an operation panel (not shown) of the image forming apparatus. When the output logic setting process is executed, the control unit 300 starts sheet feeding from a predetermined sheet feeding deck (PU1 to PU3) and passes through the replaced sheet detection sensor (PS9, PS10). The sheet is conveyed to the conveyance path. Unlike the transport control of the printing operation, the above-described transport control is controlled at a predetermined speed from paper feed to paper discharge. Further, in the above-described conveyance control, the detection value of the sheet detection sensor is not reflected in the conveyance control. When the output logic setting process is executed, the control unit 300 turns on all the sheet detection sensors (PS9, PS10) and starts sampling.

  Here, the control unit 300 acquires the detection values at three different timings and stores them in the predetermined memory area 2 of the RAM 303. The detection values at three different timings are the initial detection value of the sheet detection sensor (when there is no paper), the detection value when a sheet is detected (when there is paper), and the output logic when the sheet passes the detection area. This is the detection value (when there is no paper) when the sheet is reversed again. FIG. 5 is a timing chart showing changes in the output logic of the sheet detection sensors (PS9, PS10) when the output logic setting process is executed. The output logic of PS9 becomes LOW (the notation in FIG. 5 is L) in the time zone when the sheet does not reach the detection area of each sensor, and when the sheet reaches the detection area of the sensor, the output logic becomes HIGH (see FIG. 5). The notation is H). Then, when the sheet finishes passing through the detection area, the output logic becomes LOW again.

  On the other hand, the output logic of the PS 10 becomes HIGH during the time period when the sheet has not reached the detection area of the sensor, and the output logic becomes LOW when the sheet reaches the detection area of the sensor. Then, when the sheet finishes passing through the detection area, the output logic becomes HIGH again. In this way, the output logic changes in three stages, and the control unit 300 stores each output logic in the predetermined memory area 2 of the RAM 303 (FIG. 6). Tps9_e1 to Tps10_e2 are timing charts showing changes in output logic when a sheet is conveyed at a predetermined timing. However, in reality, the timing when the output logic changes due to the influence of the tolerance of the transport roller may not coincide with the predetermined timing.

  Next, an operation flow of the CPU 301 when the output logic setting process is executed will be described with reference to FIG. When the output logic setting process is executed by an operation from the operation panel (not shown), the CPU 301 turns on the power sources of the sheet conveyance detection sensors (PS1 to PS23) (S1). Further, the CPU 301 starts driving the carry motor (S2). Here, the carry motor is a drive source of a carry roller for carrying the sheet detected by the sheet detection sensors PS9 and PS10. In the present embodiment, the sheets fed from the sheet feeding cassette CST1 are the registration roller R10, the secondary transfer roller pair R11, the fixing unit UN3, the sheet discharge reversing unit UN4, the decal unit UN5, and the sheet discharge roller pair R15. It passes through the transport route that is transported in order. Then, in the drive control of the transport motor, the sheet is transported through the transport path at a predetermined transport speed without using the detection timing of the sheet detection sensor.

  The CPU 301 stores the output logic of the sheet detection sensors PS9 and PS10 in the memory area 2 of the RAM 303 as an initial value (S3), and inputs 9 as the center selection parameter X to select the sheet detection sensor PS9 (S4). Next, the CPU 301 waits until the output logic of the sheet detection sensor PS9 changes from the initial value (S5). When the output logic changes in step S5, the CPU 301 stores the output logic of the sheet detection sensor PS9 in the memory area 2 of the RAM 303 (S6). The output logic stored in the memory area 2 in step S6 is referred to as logic change 1.

  Next, the CPU 301 waits until the output logic of the sheet detection sensor PS9 changes again (S7). When the output logic changes in step S7, the CPU 301 stores the output logic of the sheet detection sensor PS9 in the memory area 2 of the RAM 303 (S8). The output logic stored in the memory area 2 in step S8 is referred to as logic change 2. Then, the CPU 301 determines whether the output logic of the initial value of the sheet detection sensor PS9 matches the output logic of the logic change 2 and the output logic of the initial value does not match the output logic of the logic change 1 (S9). ). If the condition is not satisfied in S9 (No), it is suspected that the sensor is broken or the line is missing. Therefore, the CPU 301 displays a message such as an error on the operation panel (S10), and terminates the sheet passing (S14). ), And ends the output logic setting process.

  On the other hand, if the condition is satisfied in step S9 (Yes), it is determined that the output logic of the sheet detection sensor PS9 is determined, and the CPU 301 stores the output logic when there is no paper in the memory area 1 of the ROM 303 (S11). ..

  Subsequently, the CPU 301 determines whether the sensor selection parameter X is 10 (S12), and when the sensor selection parameter X is not 10, increments the sensor selection parameter X by 1 (S13). As a result, the sheet detection sensor PS10 is selected, and the CPU 301 shifts the processing to S5.

  On the other hand, if X = 10 in step S12, the CPU 301 shifts the processing to step S14 and ends the output logic setting processing.

  As described above, by setting the output logic of the sheet detection sensors (PS1 to PS23) as described above, even if the output logic of the sheet detection sensor is replaced by a sensor having a different output logic, the output logic of the sheet detection sensor after replacement is set. Can be reset.

  Further, for example, when stagnant paper exists in the device when executing the output logic setting process of the present invention, the stagnant paper in the device may be conveyed by a conveying roller or the like in the device. However, the output logic of the sheet detection sensor located downstream in the conveying direction of the accumulated paper changes faster than the timing determined in advance by the paper feed deck. Therefore, the CPU 301 determines that the sheet from the sheet feeding cassette is detected when the timing of the change in the output logic is within the predetermined time range, and determines that the detection is due to stagnant paper and the like when the timing is outside the predetermined time range. .. Then, if the above-mentioned timing is outside the predetermined time range, the CPU 301 may display a message on the operation panel (not shown) to remove the accumulated paper and perform the output logic setting process again. That is, the output logic table is not set based on the current detection result of the sheet detection sensor.

  Even when the staying paper does not move, the output logic of the sheet detection sensor located upstream of the staying paper in the transport direction and downstream of the staying paper may not change due to the staying paper. Therefore, the CPU 301 may be configured to determine the presence or absence of accumulated paper by providing a predetermined time range at the timing when the above output logic changes.

R5 to R11, R15 Conveying rollers PS1 to PS23 Sheet detection sensor 1Y, 1M, 1C, 1K Laser scanner 301 CPU

Claims (3)

Transporting means for transporting the sheet along the transport path,
Image forming means for forming an image on the sheet,
An optical sensor that has a light emitting unit that emits light to the transport path and a light receiving unit that receives reflected light from a sheet that is transported through the transport path, and an optical sensor that detects the sheet based on a light receiving result of the light receiving unit,
From the detection result of the optical sensor based on a determination condition, a control unit that controls the conveyance of the sheet by the conveyance unit,
A setting unit configured to cause the conveyance unit to convey the sheet, obtain a detection result of the optical sensor, and set the determination condition based on the detection result;
If the detection result of the optical sensor changes outside the predetermined time range after the setting means starts to convey the sheet, the determining means determines that another sheet is staying in the conveying path, An image forming apparatus comprising:   The image according to claim 1, wherein the determination condition is not set based on a current detection result of the optical sensor when the determination unit determines that another sheet is retained in the transport path. Forming equipment.   The image forming apparatus according to claim 1 or 2, wherein the setting unit performs the conveyance of the sheet by the conveying unit at a predetermined conveyance speed without using a detection result of the optical sensor. apparatus.

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