Inspection equipment

Abstract

The objective is to provide an inspection device that can easily identify defective sheets from a bundle of good sheets when a defective sheet is detected by the inspection device. [Solution] In an inspection apparatus comprising an inspection means for inspecting the image of a sheet formed by an image forming means, and a discharge unit for discharging the sheet whose image has been inspected by the inspection means, the apparatus is provided with a discharge means that discharges a first sheet whose image is determined to be normal by the inspection means to a first position in the discharge unit, and discharges a second sheet whose image is determined to be abnormal to a second position offset from the first position in the discharge unit where the first sheet is discharged.

Description

Technical Field

[0001] The present invention relates to an inspection apparatus for inspecting an image of a sheet printed by an image forming apparatus.

Background Art

[0002] An inspection apparatus for inspecting an image of a sheet printed by an image forming apparatus such as a copying machine or a printer is known. This inspection apparatus includes reading means for reading an image of a sheet printed by the image forming apparatus, compares the image data read by the reading means with the image data used to print the image on the sheet, and generally detects image defects such as streaks, bleeding, distortion, chipping of the image printed on the sheet, and the color, position, etc. of the image. Then, good sheets determined to be normal by the inspection apparatus are discharged to a paper discharge tray, and defective sheets determined to be defective are discharged to a purge tray different from the paper discharge tray, and are sorted from the good sheets (for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, when inspecting an image of a sheet with page order by an inspection apparatus and discharging a defective sheet detected with an image defect to a purge tray different from the paper discharge tray where good sheets are discharged, there is a problem that it is troublesome to find a page from which a defective sheet has been removed, that is, a missing page, from the bundle of good sheets discharged to the paper discharge tray.

[0005] An object of the present invention is to provide an inspection apparatus that can easily find a defective sheet from a bundle of good sheets when a defective sheet is detected by the inspection apparatus. [Means for solving the problem]

[0006] To achieve the above objective, the present invention provides a paper feeding device comprising an inspection means for inspecting the image of a sheet formed by an image forming means, and an discharge unit for discharging the sheet whose image has been inspected by the inspection means, wherein the inspection means discharges a first sheet whose image is determined to be normal to a first position in the discharge unit, and discharges a second sheet whose image is determined to be abnormal to a second position which is moved in the width direction perpendicular to the sheet discharge direction relative to the first position in the discharge unit where the first sheet is discharged. [Effects of the Invention]

[0007] With the above configuration, when a defective sheet is detected by the inspection device, the page of the defective sheet can be easily identified. [Brief explanation of the drawing]

[0008] [Figure 1] This is a cross-sectional view showing an example of an image forming system including the inspection device of the present invention. [Figure 2] This is a cross-sectional view showing the configuration of the inspection device. [Figure 3] This diagram shows the shift mechanism in an inspection device. [Figure 4] This figure shows the separation mechanism of a pair of separating rollers in an inspection device. [Figure 5] This is a block diagram of the control system for the inspection device. [Figure 6] This is a flowchart illustrating the operation of the inspection device. [Figure 7] (a) shows the paper output status of defective sheets to the stacker. (b) shows the paper output status to the stacker when one job is completed. (c) shows the paper output status of reprinted sheets to the stacker after one job is completed. [Figure 8](a) is a diagram showing the state of paper output and stacking of sheets into the stacking stacker in the first modified example. (b) is a diagram showing the state of paper output and stacking of sheets into the stacking stacker in the second modified example. [Modes for carrying out the invention]

[0009] Figure 1 is a cross-sectional view showing the configuration of an image forming system. The image forming apparatus A is connected to an information processing device PC, such as a personal computer, in a communication manner. The information processing device PC includes an operation unit 60 for inputting settings related to paper feeding, image forming, and post-processing of the image forming system, including the image forming apparatus A, and a display unit 61 for displaying various information related to paper feeding, image forming, and post-processing of the image forming system.

[0010] The information processing device PC transmits the print data to the image forming apparatus A and then issues a print command to the image forming apparatus A. Upon receiving the print command, the image forming apparatus A prints an image on the sheet based on the print data.

[0011] An image forming system is composed of multiple devices having different functions that are interconnected. In this embodiment, as shown in Figure 1, the system is composed of an image forming apparatus A, a paper feeder B, an inspection apparatus C including a stacker 32, and a post-processing apparatus D, all of which are connected to each other.

[0012] Image forming apparatus A includes an image forming unit 2 that forms an image on paper transported from paper feeder B or paper feed unit 3 using toner. The image forming unit 2 includes a paper feed unit 3, a feeding path 10, a transport path 11, developing stations 5Y, 5M, 5C, and 5K, an intermediate transfer belt 6, and a fixing unit 8. It also includes an output path 12, an inversion path 13, and a double-sided transport path 14.

[0013] The paper feeding unit 3 is equipped with paper feeding cassettes 3a and 3b, and separates the top sheet of the sheets contained in the paper feeding cassettes 3a and 3b and transports it to the feed path 10. The developing stations 5Y, 5M, 5C, and 5K use colored toners Y, M, C, and K, respectively, to form a toner image in order to form an image based on the print data. The toner image formed by the developing stations 5Y, 5M, 5C, and 5K is first transferred to the intermediate transfer belt 6. The intermediate transfer belt 6 rotates in a clockwise direction as shown in Figure 1. The toner image first transferred to the intermediate transfer belt 6 is then secondarily transferred to the sheet that has been transported from the transport path 11 in the secondary transfer unit 7.

[0014] The fixing unit 8 is a unit for fixing the toner image onto the sheet. The fixing unit 8 is equipped with a pressure roller and a heating roller, and fixes the toner image onto the sheet by melting the toner transferred to the sheet as it passes between the rollers and pressing it onto the sheet. The sheet that has passed through the fixing unit 8 is discharged from the image forming apparatus A via the discharge path 12, or discharged from the image forming apparatus A via the inversion path 13 and the discharge path 12.

[0015] When the image forming apparatus A is operating in duplex mode, printing is performed on both sides of the sheet, the sheet that has passed through the fuser unit 8 is transported to the inversion pass 13, where it is inverted. The sheet inverted in the inversion pass 13 is then transported to the duplex transport pass 14, where the secondary transfer of the second image takes place at the secondary transfer position 7.

[0016] As shown in Figure 1, the paper feeder B is equipped with upper, middle, and lower storage compartments 16, 17, and 18 that can be pulled out from the front side in the figure. It also includes an upper transport path 19 for transporting sheets fed from the upper storage compartment 16, and a middle and lower transport path 20 for transporting sheets fed from the middle and lower storage compartments 17 and 18. A common transport path 21 is located between the upper storage compartment 16 and the middle storage compartment 17. Sheets stored in the upper, middle, and lower storage compartments 16, 17, and 18 are supplied to the image forming apparatus A via the upper transport path 19 or the middle and lower transport path 20, and then via the common transport path 21.

[0017] The inspection device C includes an inspection unit 30 that inspects the sheet image and the position of the image on the sheet, etc., a stacker 32 that stacks sheets, an upper surface tray 33 from which the sheets are discharged, and a shift unit 31 that shifts, that is, offsets, the sheet in the width direction orthogonal to the conveyance direction.

[0018] The post-processing device D performs post-processing on the conveyed sheet. The post-processing is selected by the user at the operation unit 60. In the present embodiment, it has the functions of single-stitching at one location on the edge of the sheet, double-stitching at two locations on one side of the sheet, and saddle stitching binding, and the user can select any one of them. The post-processing device D includes a stitching processing unit 23 that performs single-stitching or double-stitching on the sheet, and a binding processing unit 24 that binds the sheet by folding it in half after performing saddle stitching on the sheet. In addition, the post-processing device D is provided with a first post-processing path 25 that conveys the sheet conveyed from the fourth conveyance path 37 of the inspection device C to the stitching processing unit 23, and a second post-processing path 26 that branches from the first post-processing path 25 and conveys the sheet to the binding processing unit 24.

[0019] When the post-processing device D performs single-stitching or double-stitching on the sheet, it conveys the sheet from the first post-processing path 25 to the stitching processing unit 23, performs needle stitching with the stapler 23a provided in the stitching processing unit 23, and then discharges it to the discharge tray 27. On the other hand, when binding the sheet, it conveys the sheet from the first post-processing path 25 through the second post-processing path 26 to the binding processing unit 41, performs saddle stitching and double-folding on the sheet with the saddle-stitching stapler 24a and the folding roller pair 24b provided in the binding processing unit 24, and stores the bound sheet in the storage tray 45.

[0020] Here, the inspection device C will be described in detail based on FIG. 2. FIG. 2 is a cross-sectional view of the inspection device C. As described above, the inspection device C includes an inspection unit 30, a stacker 32, an upper surface tray 33, and a shift unit 31.

[0021] Furthermore, inspection apparatus C has a first transport path 34 from an inlet that receives sheets from image forming apparatus A to a first switching flapper 38, a second transport path 35 from the first switching flapper 38 to a stacker 32, a third transport path 36 from the first switching flapper 38 to an upper tray 33, and a fourth transport path 37 from the second switching flapper 39 to an outlet that sends sheets to post-processing apparatus D. The first switching flapper 38 guides sheets from the first transport path 34 to either the second transport path 35 or the third transport path 36. The second switching flapper 39 also guides sheets being transported on the second transport path 35 to either the upper tray 33 or the fourth transport path 37.

[0022] The inspection unit 30 located upstream (inlet side) of the first transport path 34 is equipped with first and second inspection units 30a and 30b. The first inspection unit 30a is located below the first transport path 34 in the vertical direction and reads an image of one side of the sheet. The second inspection unit 30b is located above the first transport path 34 in the vertical direction and reads an image of the other side of the sheet.

[0023] The first and second inspection units 30a and 30b in this embodiment are so-called contact image sensors, configured by arranging a CCD (photoelectric conversion element), an LED light source, and a rod lens array (equal-magnification imaging system lens) in a line extending in the sheet width direction. Alternatively, the inspection units 30a and 30b may be configured to read images using a digital camera or the like.

[0024] The downstream side of the first transport path 34 is positioned, and the shift section 31 is equipped with a shift roller pair 31a and a separation roller pair 31b. The shift roller pair moves in the width direction perpendicular to the transport direction of the sheet while the sheet is nipped, shifting (offsetting) the sheet's position in the width direction. The separation roller pair separates to release the sheet's nip while the shift roller pair moves in the width direction. This allows the sheet to move freely in the width direction as the shift roller pair moves in the width direction.

[0025] The shift mechanism will now be described based on Figure 3. The shift mechanism includes a rack 43 for moving the shift roller pair 31a, a pinion 44, and a shift motor MT5 for driving the pinion 44. A connecting plate 46 is attached to the rack 43, and the shaft 41a of one roller 41 and the shaft 42a of the other roller 42 of the shift roller pair 31a are rotatably attached to this connecting plate 46.

[0026] When the shift motor MT5 is rotated forward (counterclockwise in Figure 3), the pinion 44 rotates forward (clockwise in Figure 3), and the rack 43 and connecting plate 46 move to the right in the sheet width direction in Figure 3. Conversely, when the shift motor MT5 is rotated backward (clockwise in Figure 3), the pinion 44 rotates backward (counterclockwise in Figure 3), and the rack 43 and connecting plate 46 move to the left in the sheet width direction in Figure 3. This movement of the connecting plate 46 causes the shift roller pair 31a and the two shafts 41a and 42a to move in the sheet width direction. As shown in Figure 3, by moving the shift roller pair 31a from the first position to a second position, which is a predetermined amount in the sheet width direction, with the sheet nipped by the shift roller pair 31a, the sheet can be shifted (offset) from its normal transport position to a position a predetermined amount in the sheet width direction.

[0027] Next, the separation mechanism will be described with reference to Figure 4. The separation mechanism includes an arm member 49 that supports one roller 47 of the separation roller pair 31b at one end and is attached to a shaft 49a at the other end, and a separation motor MT6 that swings this arm member 49 to move one roller 47 to a position where it is separated from the other roller 48 or pressed against the other roller 48.

[0028] In this separation mechanism, when the separation motor MT6 is rotated forward (clockwise in Figure 4), the shaft 49a rotates forward. As a result, the arm member 49 attached to the shaft 49a rotates away from the other roller 48, and one roller 47 attached to one end of the arm member 49 moves to a separated position, separated from the other roller 48. On the other hand, when the separation motor MT6 is rotated in the reverse direction (counterclockwise in Figure 4), the shaft 49a rotates in the reverse direction. As a result, the arm member 49 rotates away from the other roller 48, and one roller 47 moves to a contact position, pressing against the other roller 48.

[0029] The stacker 32 is capable of accumulating thousands of sheets and is retractably mounted on the front side of the inspection device C. The stacker 32 is equipped with an accumulation tray 32a for accumulating sheets. When the top surface of the sheets to be accumulated reaches a predetermined position, the accumulation tray 32a lowers by a certain amount to receive sheets from the second transport path 35.

[0030] The stacker 32 is configured to move between a mounting position inside the inspection device C and a pull-out position extending outside the inspection device C. When receiving sheets from the second transport path 35, the stacker 32 is held in the mounting position. When removing the accumulated sheets from the stacker 32, the user releases the hold by operating an operation button (not shown). This makes the stacker 32 movable. The user can remove the accumulated sheets from the stacker 32 by pulling the movable stacker 32 forward and moving it to the pull-out position.

[0031] The top tray 33 can hold up to approximately 100 sheets. By selecting this top tray 33, sheets can be easily removed, making it suitable for handling relatively small numbers of sheets.

[0032] Figure 5 is a control block diagram of the inspection device C. As shown in Figure 5, the inspection device C is equipped with first to fourth transport motors MT1, MT2, MT3, MT4, a shift motor MT5, a separation motor MT6, a lifting motor MT7, and first and second solenoids SOL1 and SOL2. Briefly describing each motor and solenoid, the first transport motor MT1 drives the first transport roller pair R1, the second transport roller pair R2, and the third transport roller pair R3 located in the inspection unit 30, and the fourth transport roller pair R4, the fifth transport roller pair R5, and the sixth transport roller pair R6 located in the section of the first transport path 34 from the inspection unit 30 to the shift unit 31. The second transport motor MT2 drives the separation roller pair 31b and the shift roller pair 31a located in the shift unit 31. Furthermore, the third transport motor MT3 is configured to drive the first paper discharge roller pair R12 located in the second transport path 35 in forward rotation and the seventh transport roller R7 located between the first and second switching flappers 38 and 39 in the third transport path 36 in reverse rotation. The fourth transport motor MT4 is configured to drive the second paper discharge roller pair R13 and the eighth transport roller pair R8 located in the third transport path 36 in forward rotation and the ninth transport roller R9, the tenth transport roller R10, and the eleventh transport roller R11 located in the fourth transport path 37 in reverse rotation.

[0033] The shift motor MT5 moves the shift roller pair 31a in the sheet width direction, and the separation motor MT6 separates the separation roller pair. The lifting motor MT7 raises and lowers the stacking tray 32a of the stacker 32. In addition, the first solenoid activates the first switching flapper 38, guiding the sheet being transported from the first transport path 34 toward the third transport path 36 to the second transport path 35. The second solenoid activates the second switching flapper 38, guiding the sheet being transported toward the third transport path 36 to the fourth transport path 37.

[0034] Furthermore, the inspection device C is equipped with first to fifth sensors SE1, SE2, SE3, SE4, and SE5 for detecting sheets. The first sensor SE1 is located at the entrance of the inspection device C and activates the first inspection unit 30a and the second inspection unit 30b based on the detection of the leading edge of the sheet by the first sensor SE1. The second sensor SE2 is located in the shift unit 31 and detects the leading edge of the sheet in order to stop and shift (offset) the sheet in the shift unit. The third sensor SE3 detects the trailing edge of the sheet being discharged to the stacker 32. Based on the detection result of this third sensor SE3, it is determined that the sheet has been discharged to the stacker 32. The fourth sensor SE4 detects the trailing edge of the sheet being discharged to the top tray 33. Based on the detection result of this fourth sensor SE4, it is determined that the sheet has been discharged to the top tray 33. The fifth sensor SE5 is located at the entrance of the inspection device C and detects the trailing edge of the sheet.

[0035] Each of the sensors SE1, SE2, SE3, SE4, and SE5 is connected to a control unit (control means) 100 having a CPU, ROM, and RAM. The control unit 100 acquires the state of the sheet based on the sheet detection signals from each of the sensors SE1, SE2, SE3, SE4, and SE5. Based on various information from the image forming apparatus A and the detection signals from each of the sensors SE1, SE2, SE3, SE4, and SE5, the control unit 100 controls the driving of each motor MT1, MT2, MT3, MT4, MT5, MT6, and MT7 and each solenoid SOL1 and SOL2. Furthermore, based on the inspection results of the first inspection unit 30a and the second inspection unit 30b, the control unit 100 controls the shift motor MT6 and the separation motor MT7 to shift (offset) the sheet in the width direction.

[0036] Figure 6 is a flowchart illustrating the operation of inspecting the image on a sheet from the image forming apparatus A and discharging it to the stacker 32. Discharging to the stacker 32 can be set using the operation unit 60. When the stacker 32 is selected as the discharge location, the first switching flapper 38 is moved by the first solenoid SOL1 to a position that guides the sheet from the first transport path 34 to the second transport path 35 before the sheet printed by the image forming apparatus A is transported to the inspection apparatus C.

[0037] Based on Figure 6, the operation of the inspection device C will be explained as follows: First, when the first sensor SE1 detects the leading edge of the sheet from the image forming apparatus A, it drives the first transport motor MT1 and the second transport motor MT2. As a result, the first to third transport roller pairs R1, R2, and R3 located in the inspection unit 30, and the fourth to sixth transport roller pairs R4, R5, and R6, the separation roller pair 31b, and the shift roller pair 31a located downstream of the inspection unit 30 rotate, and the sheet is transported along the first transport path 34 (ST10 to ST11).

[0038] Then, based on the detection of the sheet's leading edge by the first sensor SE1, the first inspection unit 30a and the second inspection unit 30b each operate at predetermined timings to perform the reading process (ST12).

[0039] In the reading process, if the printing mode is single-sided, i.e., printing is performed on only one side of the sheet, the first inspection unit 30a is activated to read one side of the sheet. On the other hand, if the printing mode is double-sided, printing is performed on both sides of the sheet, the first inspection unit 30a and the second inspection unit 30b are activated to read both sides of the sheet.

[0040] In this process, the image forming apparatus A receives print image data to be printed from the information processing device PC and prints the image onto the sheet based on this print image data. In the reading process, the first and second inspection units 30a and 30b read the image on the printed sheet, transfer the read image data to the control unit 100, and store it as read image data in the RAM of the control unit 100.

[0041] Once the sheet is read, the read image determination process is performed (ST13). This read image determination process compares the read image data stored in the RAM of the control unit 100 with the print image data to be printed in the image forming apparatus A. That is, the read image determination process calculates difference data between the read image data and the print image data, extracts the differences between the read image data and the print image data based on this difference data, and determines whether the printed image is good or bad. For example, by obtaining the difference data of the gradation of each corresponding pixel in the read image data and the print image data, if the difference data is greater than or equal to a predetermined gradation difference threshold, it can be determined that the image is defective. In this embodiment, since it is a color image, each image data is divided into planes of each color component in the CMYK color space or RGB color space, and gradation difference data is calculated for each plane of each color component.

[0042] In the above-described embodiment, a method for detecting differences based on grayscale difference data was explained, but the method for detecting differences is not limited to this. For example, various image analysis methods and image processing methods can be applied, such as detecting differences based on the correlation of pixels included in the read image data.

[0043] The sheet whose image quality has been determined in the image reading and judgment process (ST13) is transported downstream along the first transport path 34. If the second sensor SE2 of the shift unit 31 detects the leading edge of the sheet and the image reading and judgment process determines that the sheet's image quality is good, the third transport motor MT3 is driven in the forward direction (ST14~ST16). As a result, the first paper discharge roller pair R7 rotates, and the sheet transported from the first transport path 34 to the second transport path 35 is discharged to the stacker 32. After a predetermined time has elapsed since the second sensor SE2 located on the second transport path 35 detected the trailing edge of the sheet, the third transport motor MT3 is stopped, as the sheet has been discharged to the stacker 32 (ST17~ST19).

[0044] On the other hand, if the second sensor SE2 detects the leading edge of the sheet and the image quality of the sheet is determined to be defective in the image reading process, the second transport motor MT2 is stopped (ST14-ST15, ST20). As a result, the sheet stops at the position where its leading edge has reached the second sensor SE2. Once the sheet stops, the shift process is executed (ST21).

[0045] In the shift process (ST21), the separation motor MT6 is rotated forward to move one roller 47 to a separated position away from the other roller 48 and stop. Then, the shift motor MT5 is driven forward to move the shift roller pair 31a from the first position to the second position and stop. As a result, the shift roller pair 31a is shifted (offset) by a predetermined amount in the sheet width direction.

[0046] When the shift process is completed, the second transport motor MT2 is driven and the third transport motor MT3 is rotated forward (ST22~ST23). As a result, the shift roller pair 31a and the first paper discharge roller pair R7 rotate, and the sheet in the shift unit 31 is transported from the first transport path 34 to the second transport path 35. When the second sensor SE2 located in the second transport path 35 detects the rear end of the sheet, the shift unit default process is executed (ST24~ST25). After a predetermined time has elapsed since the second sensor SE2 detected the rear end of the sheet, the third transport motor MT3 is stopped, as it is assumed that the sheet has been discharged to the stacker 32 (ST17~ST19). As a result, sheets that have been determined to have poor image quality in the reading image judgment process are discharged to the stacker 32 offset from the position of the good sheets determined to be good, and are distinguished from good sheets within the stacking stacker 32 (see Figure 7(a)).

[0047] In the default shift section processing (ST21) described above, the separation motor MT6 is reversed to return one roller 47 to the contact position where it is pressed against the other roller 48 and then stops. At the same time, the shift motor MT5 is reversed to return the shift roller pair 31a from the second position to the first position, making the shift section ready to receive the next sheet. Subsequently, when the first sensor SE1 detects the leading edge of the sheet from the image forming apparatus A, the above operations are executed sequentially, and when one job is completed, the inspection apparatus C is stopped.

[0048] Figure 7(b) shows the sheet stacking state in the stacker 32 when the Nth sheet in a job is a defective sheet PD. Up to the (N-1)th sheet, the sheets are discharged to the stacker 32 without being shifted (offset) by the shift unit 31. The Nth sheet, which is determined to be a defective product, is then shifted by the shift unit 31 and discharged to the stacker 32. From there, from the (N+1)th sheet to the final sheet of a job, the sheets are discharged to the stacker 32 without being shifted (offset) by the shift unit 31.

[0049] As described above, the shift section 31 of the first transport path 34 shifts (offsets) the sheets determined to be defective in the sheet width direction and discharges them to the stacker 32. As shown in Figures 7(a) and 7(b), defective sheets PD, which are determined to have poor image quality, are shifted (offset) by a predetermined amount (L) relative to good sheets PN, which are determined to be good, and are accumulated in the stacker 32. Therefore, even if good sheets P1 and defective sheets P2 are discharged to the same stacker 32, the defective sheets P2 can be easily identified.

[0050] In this embodiment, when an image forming apparatus A completes a job, it performs a reprint operation to reprint any sheets deemed defective within that job. In the inspection apparatus C of this embodiment, the reprinted sheets are also shifted by the shift unit and discharged to the stacker 32. At this time, as shown in Figure 7(c), the reprinted sheet PR is discharged on top of the sheet PN in the stacker 32 after a job has been completed, and is moved to a different position from the defective sheet PD by the shift mechanism before being discharged. This makes it easy to distinguish good sheets from defective sheets, even if sheets deemed defective are discharged to the same discharge unit. In this embodiment, as shown in Figure 7(c), the reprinted sheets are moved and discharged in a direction different from the direction in which the defective sheets were moved. However, this is not the only method; it is sufficient if good sheets, defective sheets, and reprinted sheets are in different positions and can be distinguished.

[0051] After one job and the defective sheet have been reprinted, the user removes the defective sheet from the sheet stack, inserts the reprinted sheet (which has been applied to the removed defective sheet) into the position where the defective sheet was, and completes a stack of good sheets.

[0052] Furthermore, if there are multiple defective sheets, as shown in Figure 8(a), the defective sheet PD2, which is discharged later, may be discharged with a predetermined amount of offset from the defective sheet PD1, which is discharged first, and the two reprinted sheets PR1 and PR2, which correspond to the two defective sheets PD1 and PD2, may also be discharged with an offset. By making the amount of offset between the two defective sheets PD1 and PD2 and the two reprinted sheets PR1 and PR2 the same, it becomes easy to determine which reprinted sheet PR1 corresponds to the first defective sheet PD1 and which reprinted sheet PR2 corresponds to the second defective sheet PD2, making it easy for the user to replace the defective sheets with reprinted sheets.

[0053] Furthermore, in the above embodiment, the Nth defective sheet is shifted (offset), and the good sheets before and after it are discharged at the same position. However, the discharge position of the good sheets following the defective sheet may be set to a different position from the discharge position of the good sheets discharged before the defective sheet. In other words, as shown in Figure 8(b), good sheets PNA up to the N-1th sheet are discharged to the stacker 32 without shifting (offsetting) the sheets in the shift unit 31, and the Nth sheet, which is determined to be defective, is shifted (offset) by the shift unit 31 as a defective sheet PD and discharged to the stacker 32. Then, sheets PNB from the N+1th sheet onward, which are determined to be good, following the Nth sheet determined to be defective, are discharged at a position shifted (offset) in the opposite direction to the shift direction of the defective sheet PD relative to the discharge position of the good sheets PNA up to the N-1st sheet. Furthermore, the reprinted sheets PR are discharged at a different location than the discharge location for good sheets PNA up to N-1 sheets, the discharge location for defective sheets PD, and the discharge location for good sheets PNB from N+1 sheets onward.

[0054] This makes defective sheets PD easier to see, and because the stacks of good sheets PNA above and below the defective sheets PD accumulated in the stacker 32 are misaligned, it is easy to separate the stacks of good sheets above and below the defective sheet, remove the defective sheet, and insert a reprinted sheet. [Explanation of Symbols]

[0055] A Image forming apparatus B Paper feeder C Inspection device D Post-processing device PC Information Processing Device 30 Inspection Department 30a First inspection unit 30b Second inspection unit 31 Shift section 31a Shift roller pair 31b Separating roller pair 32 stacking rack 33 Top tray 34. First transport path 35. Second transport path 36. Third transport path 37. Fourth transport path 38. First switching flapper 39. Second switching flapper

Claims

1. An inspection apparatus comprising an inspection means for inspecting an image formed on a sheet by an image forming means, and a discharge unit for discharging the sheet whose image has been inspected by the inspection means, An inspection apparatus comprising a discharge means for discharging a first sheet whose image is determined to be normal by the inspection means to a first position in the discharge unit, and discharging a second sheet whose image is determined to be abnormal to a second position offset from the first position in the discharge unit from which the first sheet is discharged.

2. The inspection apparatus according to claim 1, wherein the second position is a position offset from the first position in a direction perpendicular to the sheet discharge direction.

3. The inspection apparatus according to claim 1, wherein the discharge means discharges a third sheet on which a normal image corresponding to the second sheet is printed to a third position different from the first and second positions of the discharge unit.

4. An inspection apparatus comprising an inspection means for inspecting an image formed on a sheet by an image forming means, and a discharge unit for discharging the sheet whose image has been inspected by the inspection means, The system includes a discharge means that discharges a first sheet whose image is determined to be normal by the inspection means to a predetermined position in the discharge unit, and discharges a second sheet whose image is determined to be abnormal to a position offset from the predetermined position in the discharge unit. The discharge means is an inspection device that, when there are multiple second sheets, discharges the multiple second sheets to positions where the offset amount of each second sheet relative to the predetermined position is different.

5. The inspection apparatus according to claim 4, wherein the discharge means discharges a plurality of third sheets, each having a normal image corresponding to a plurality of second sheets printed on it, to different positions in the discharge unit.

6. An inspection apparatus comprising an inspection means for inspecting an image formed on a sheet by an image forming means, and a discharge unit for discharging the sheet whose image has been inspected by the inspection means, The inspection means discharges the first sheet, whose image is determined to be normal, to the discharge unit, and also provides a discharge means that discharges the second sheet, whose image is determined to be abnormal, to a position in the discharge unit that is offset from the discharge position of the first sheet, which was discharged prior to the second sheet, which was determined to have an abnormal image. The discharge means is an inspection device that discharges the first sheet following the second sheet to a position different from the discharge position of the first sheet preceding the second sheet.

7. The inspection apparatus according to any one of claims 1 to 6, wherein the discharge means is a moving means for moving the sheet in a width direction perpendicular to the discharge direction.

Images