Image forming device and image forming method

Abstract

To provide an image forming device and an image forming method capable of detecting skew of a sheet before the sheet is heated by a heating part.SOLUTION: An image forming device 1 comprises a feeding and conveying part 2, an image forming part 3, a heating part 4, and a skew detecting part 5. The feeding and conveying part 2 feeds and conveys a sheet S. The image forming part 3 forms an image on the sheet S fed and conveyed by the feeding and conveying part 2. The heating part 4 heats the sheet S on which the image is formed by the image forming part 3. The skew detecting part 5 is arranged on the conveying direction upstream side than the heating part 4, to detect skew of the sheet S before the sheet S reaches the heating part 4.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an image forming apparatus and an image forming method. [Background technology]

[0002] Patent Document 1 discloses a paper sheet sorting device that detects whether a paper sheet is skewed with respect to the conveying direction and changes the time until a gate means for switching the conveying direction is operated according to the amount of skew. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 11-292350 Summary of the Invention [Problem to be solved by the invention]

[0004] However, Patent Document 1 does not disclose the relationship between the timing at which the skew of the sheet is detected and the timing at which the sheet approaches the heating unit.

[0005] SUMMARY OF THE PRESENT EMBODIMENT An object of the present invention is to provide an image forming apparatus and an image forming method capable of detecting a skew of a sheet before the sheet is heated by a heating section. [Means for solving the problem]

[0006] The image forming apparatus according to the present invention includes a feeding and conveying section, an image forming section, a heating section, and a skew detection section. The feeding and conveying section feeds and conveys a sheet. The image forming section forms an image on the sheet fed and conveyed by the feeding and conveying section. The heating section heats the sheet on which the image has been formed by the image forming section. The skew detection section is disposed upstream of the heating section in the conveying direction, and detects skew of the sheet before the sheet approaches the heating section.

[0007] The image processing method of the present invention includes a step of a feeding and conveying unit feeding and conveying a sheet, a step of an image forming unit forming an image on the sheet fed and conveyed by the feeding and conveying unit, a step of a heating unit heating the sheet on which the image has been formed by the image forming unit, and a step of a skew detection unit arranged upstream of the heating unit in the conveying direction detecting skew of the sheet before the sheet approaches the heating unit. Effect of the Invention

[0008] According to the present invention, it is possible to provide an image forming apparatus and an image forming method that detect a skew of a sheet before the sheet is heated by a heating section. [Brief description of the drawings]

[0009] [Figure 1] 1 is a diagram illustrating an image forming apparatus according to an embodiment of the present invention. [Diagram 2] 1 is a diagram illustrating a configuration of an image forming unit of an image forming apparatus according to an embodiment of the present invention. [Diagram 3] 3A and 3B are diagrams illustrating the configuration of a feeding / conveying unit and a skew detection unit of an image forming apparatus according to the present embodiment. [Figure 4] 1A and 1B are diagrams illustrating a manner in which a skew detection unit detects a skew. [Diagram 5] 1A and 1B are diagrams illustrating the configuration of a heating unit and a skew detection unit. [Figure 6] 1A and 1B are diagrams illustrating configurations of a skew detection unit, a sheet detection unit, and an evacuation unit. [Figure 7] 2 is a flowchart showing an image forming method according to an embodiment of the present invention. [Figure 8] 2 is a flowchart showing an image forming method according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an image forming apparatus 1 according to an embodiment of the present invention will be described with reference to the drawings. In the drawings, the same or corresponding parts are designated by the same reference characters and description thereof will not be repeated.

[0011] First, an outline of the configuration of an image forming apparatus 1 according to an embodiment of the present invention will be described with reference to Fig. 1. Fig. 1 is a diagram showing the image forming apparatus 1 according to an embodiment of the present invention. Fig. 1 is a diagram showing the image forming apparatus 1 as viewed from the front.

[0012] As shown in FIG. 1, the image forming apparatus 1 includes a feeding / conveying section 2, an image forming section 3, a heating section 4, a skew detecting section 5, a sheet detecting section 6, an evacuation section 7, and a discharge section 8.

[0013] The feeding and conveying section 2 feeds and conveys the sheet S.

[0014] The image forming unit 3 forms an image on the sheet S fed and conveyed by the feeding and conveying unit 2.

[0015] The heating section 4 heats the sheet S on which an image has been formed by the image forming section 3. The heating section 4 heats the sheet S to dry the image formed on the sheet S.

[0016] The skew detection unit 5 is disposed upstream of the heating unit 4 in the conveying direction, and detects skew of the sheet S before the sheet S approaches the heating unit 4. Skew means that the sheet S is inclined with respect to the feeding / conveying direction.

[0017] "Before the sheet S reaches the heating section 4" refers to a state before the portion of the sheet S on which an image has been formed by the image forming section 3 is heated by the heat of the heating section 4.

[0018] According to this embodiment, the image forming apparatus 1 can detect the skew of the sheet S before the sheet S approaches the heating section 4. Therefore, the image forming apparatus 1 can detect the skew of the sheet S before the sheet S is heated by the heating section 4.

[0019] By detecting the skew of the sheet S before the sheet S is heated by the heating unit 4, the skewed sheet S can be prevented from entering the area heated by the heat of the heating unit 4.

[0020] Furthermore, by preventing the skewed sheet S from entering the area heated by the heat of the heating section 4, it is possible to prevent the skewed sheet S from getting caught in the heating section 4, for example, and becoming stuck in the heating section 4, resulting in excessive heating.

[0021] The sheet detection unit 6 detects that a sheet is being conveyed to the heating unit 4.

[0022] The evacuation section 7 evacuates the sheet S from the heating section 4 .

[0023] The discharge section 8 discharges the sheet S to the outside of the image forming apparatus 1.

[0024] Next, the image forming apparatus 1 will be described in further detail with reference to FIG. 1 as well as to FIG. 2 to FIG. 6(b).

[0025] First, each component of the image forming apparatus 1 will be described with reference to FIG.

[0026] As shown in FIG. 1, the feeding / conveying section 2 includes a feeding device 20, a conveying device 21, a motor 22, and a first conveying control section .

[0027] The feeding device 20 feeds the sheet S.

[0028] The feeding device 20 includes a tray 200 and a pick-up roller 201 .

[0029] The tray 200 stores the sheets S therein.

[0030] The pickup roller 201 rotates to pick up the sheet S from the tray 200. The pickup roller 201 feeds the picked-up sheet S to the conveying device 21.

[0031] The conveying device 21 conveys the sheet S.

[0032] The conveying device 21 includes a conveying path 210 and a supply / conveying roller 211 .

[0033] The sheet S is conveyed along the conveying path 210. The conveying path 210 is formed to extend from the feeding device 20 toward the image forming unit 3.

[0034] The feeding and conveying rollers 211 convey the fed sheet S to the conveying path 210. The feeding and conveying rollers 211 are disposed in the conveying path 210.

[0035] The motor 22 drives the feeding device 20 and the transporting device 21. The motor 22 drives the pickup roller 201 and the feeding / transporting roller 211 to rotate.

[0036] The first conveyor control unit 23 controls the driving of the supply / conveyor unit 2.

[0037] The first conveyor control unit 23 controls the rotational drive of the motor 22.

[0038] The pick-up roller 201 is rotationally driven by a motor 22 controlled by a first conveyance control unit 23 , and picks up a sheet S accommodated in the tray 200 .

[0039] The feed / conveyance roller 211 is rotated by a motor controlled by the first conveyance control unit 23 , and conveys the sheet S picked up by the pickup roller 201 to a conveyance path 210 .

[0040] The first conveyance control unit 23 stops driving the feeding and conveying unit 2 before the sheet S approaches the heating unit 4 based on the detection of the skew of the sheet S by the skew detection unit 5.

[0041] That is, the skew detection unit 5 detects the skew of the sheet S transported by the feeding and transporting unit 2. Based on the detection of the skew of the sheet S by the skew detection unit 5, the first transport control unit 23 stops driving the feeding and transporting unit 2 before the sheet approaches the heating unit 4.

[0042] According to this embodiment, the first conveyance control unit 23 stops driving the feeding / conveying unit 2 before the skewed sheet S reaches the heating unit 4. The image forming apparatus 1 can prevent the skewed sheet S from being heated by the heating unit 4.

[0043] Next, the configuration of the image forming unit 3 will be described in detail with reference to Fig. 2 in addition to Fig. 1. Fig. 2 is a diagram showing the configuration of the image forming unit 3 in detail. Fig. 2 is a diagram showing the image forming unit 3 as viewed from above.

[0044] As shown in FIGS. 1 and 2, the image forming unit 3 includes an inkjet head 30, a motor 31, a conveyor belt 32, a belt conveyor roller 33, and a second conveyor control unit .

[0045] As shown in FIGS. 1 and 2, the inkjet head 30 ejects ink onto a sheet S.

[0046] The inkjet head 30 is disposed opposite the conveyor belt 32 .

[0047] The inkjet head 30 includes a line head 30Y, a line head 30M, a line head 30C, and a line head 30K.

[0048] The line head 30Y ejects yellow ink, the line head 30M ejects magenta ink, the line head 30C ejects cyan ink, and the line head 30K ejects black ink.

[0049] Each line head 30 has nozzles 300. Ink of each color is ejected from the nozzles 300.

[0050] The motor 31 drives the belt conveying roller 33 to rotate.

[0051] The belt conveying roller 33 is rotated by a motor 31 to drive the conveying belt 32 to convey the same.

[0052] The conveyor belt 32 is, for example, an endless belt. The conveyor belt 32 is disposed so as to be wound around a belt conveying roller 33.

[0053] The conveyor belt 32 is conveyed in the direction of the arrow X by the motor 31, whereby the sheet S is conveyed in the direction of the arrow X.

[0054] The second conveyor control unit 34 controls the driving of the motor 31. The configuration of the second conveyor control unit 34 may be similar to the configuration of the first conveyor control unit 23.

[0055] Next, the configuration and operation of the skew detection unit 5 will be described in detail with reference to FIG. 1 as well as to FIGS. 3(a) and (b) and FIG.

[0056] As shown in FIG. 1 and FIG. 3( a ), the skew detection unit 5 includes a skew sensor 50 and a detection unit 51 .

[0057] The skew sensor 50 detects the sheet S transported from the upstream side in the transport direction to the downstream side in the transport direction.

[0058] When the skew sensor 50 does not detect the leading edge of the sheet S transported from the upstream side in the transport direction to the downstream side in the transport direction, it outputs a signal L. When the skew sensor 50 detects the leading edge of the sheet S, it outputs a signal H. When the skew sensor 50 detects that the trailing edge of the sheet S has passed, it outputs a signal L.

[0059] As shown in FIG. 3(a), the skew sensor 50 has a skew sensor 50a and a skew sensor 50b in the main scanning direction (the front-rear direction in FIG. 3(a) or a direction perpendicular to the conveying direction of the sheet S).

[0060] The skew sensor 50a and the skew sensor 50b output a combination of output signals used to detect the skew of the sheet S.

[0061] Specifically, the skew sensor 50a outputs a signal L when it does not detect the leading edge of the sheet S transported from the upstream side in the transport direction to the downstream side in the transport direction. When the skew sensor 50a detects the leading edge of the sheet S, it outputs a signal H. The skew sensor 50a outputs the signal H while the sheet S is passing. The skew sensor 50a outputs a signal L when it detects that the trailing edge of the sheet S has passed.

[0062] Similarly, when the skew sensor 50b does not detect the leading edge of the sheet S transported from the upstream side in the transport direction to the downstream side in the transport direction, it outputs a signal L. When the skew sensor 50b detects the leading edge of the sheet S, it outputs a signal H. The skew sensor 50b outputs a signal H while the sheet S is passing. When the skew sensor 50b detects that the trailing edge of the sheet S has passed, it outputs a signal L.

[0063] The detection unit 51 detects the skew of the sheet S based on the output of the skew sensor 50 (skew sensor 50a, skew sensor 50b).

[0064] The detection unit 51 includes, for example, an XOR circuit 510 (XOR: exclusive OR: exclusive OR circuit), a clock circuit 511, and a D flip-flop circuit 512.

[0065] The output of the XOR circuit 510 and the output of the clock circuit 511 are input to a D flip-flop circuit 512 .

[0066] The XOR circuit 510 has an input A, an input B, and an output C.

[0067] Fig. 3(b) shows a truth table of the XOR circuit 510. As shown in Fig. 3(b), the XOR circuit 510 outputs a signal H to an output C when only the input A of the two inputs A and B is a signal H, or when only the input B is a signal H.

[0068] In FIG. 3(b), when input A is signal L and input B is signal L, output C is signal L.

[0069] When input A is a signal H and input B is a signal L, output C is a signal H.

[0070] When input A is signal L and input B is signal H, output C is signal H.

[0071] When input A is signal H and input B is signal H, output C is signal L.

[0072] The clock circuit 511 alternately outputs a signal H and a signal L at a set clock frequency.

[0073] Next, with reference to FIG. 4, the output of the XOR circuit 510 based on the output of the skew sensor 50 (skew sensor 50a, skew sensor 50b) will be described.

[0074] FIG. 4 is a diagram showing the relationship between the output of the skew sensor 50 (skew sensor 50a, skew sensor 50b) and the output of the XOR circuit 510 according to the conveyance status of the sheet S.

[0075] 4, when the conveyed sheet S has not yet reached the skew sensor 50a, the skew sensor 50a outputs a signal L. The signal L is input to the input A of the XOR circuit 510.

[0076] 4, when the conveyed sheet S has not yet reached the skew sensor 50b, the skew sensor 50b outputs a signal L. The signal L is input to the input B of the XOR circuit 510.

[0077] The output C of the XOR circuit 510 outputs the signal L.

[0078] 3(a) stores the signal L at the timing of the rising edge of the signal H generated by the clock circuit 511 when the signal L is input from the XOR circuit 510. The D flip-flop circuit 512 outputs the signal L. The output of the D flip-flop circuit 512 continues to output the signal L until the signal H is input.

[0079] 3A receives a signal L from the D flip-flop circuit 512, and rotates the motor 22. The motor 22 rotates the supply and conveyance roller 211. The supply and conveyance roller 211 conveys the sheet S, or a sheet other than the sheet S being conveyed to the conveyance path 210, downstream in the conveyance direction.

[0080] That is, when the sheet S is not detected by the skew detection unit 5, the sheet S or a sheet other than the sheet S being conveyed to the conveying path 210 is conveyed by the belt conveying roller 33.

[0081] 4, when the skew sensor 50b detects the leading edge of the sheet S, the skew sensor 50b outputs a signal H at time t1. Then, the signal H is input to the input B of the XOR circuit 510 at time t1.

[0082] 4, the leading edge of the sheet S has not yet reached the skew sensor 50a at time t1. Therefore, at time t1, the skew sensor 50a outputs a signal L. The signal L is input to the input A of the XOR circuit 510 at time t1.

[0083] As shown in pattern 2 of FIG. 4, the output C of the XOR circuit 510 outputs a signal H at time t1.

[0084] That is, pattern 2 in FIG. 4 indicates that the sheet S is in a skewed state in the skew detection unit 5. In FIG.

[0085] 3(a) is input from the XOR circuit 510, the D flip-flop circuit 512 updates and stores the signal H at the timing of the rising edge of the signal H generated by the clock circuit 511. The D flip-flop circuit 512 outputs the signal H. The D flip-flop circuit 512 continues to output the signal H until a signal L is input.

[0086] 4, the leading edge of the sheet S reaches the skew sensor 50a at time t2. Therefore, the skew sensor 50a outputs a signal H. The signal H is input to the input A of the XOR circuit 510 at time t2.

[0087] As shown in pattern 2 of FIG. 4, the output C of the XOR circuit 510 continues to output the signal H even after time t2.

[0088] 3A receives a signal H from the D flip-flop circuit 512 at time t1, and stops the rotational driving of the motor 22. The motor 22 stops the rotational driving of the supply and conveyance roller 211. The supply and conveyance roller 211 stops conveying the sheet S downstream in the conveyance direction.

[0089] That is, when the skew of the sheet S is detected by the skew sensor 50, the conveyance of the sheet S is stopped before the sheet S reaches the heating unit 4.

[0090] 4, the leading edge of the sheet S reaches the skew sensor 50a at time t3. At time t3, the skew sensor 50a outputs a signal H. The signal H is input to the input A of the XOR circuit 510 at time t3.

[0091] 4, the leading edge of the sheet S has not yet reached the skew sensor 50b at time t3. Therefore, at time t3, the skew sensor 50b outputs a signal L. The signal L is input to the input B of the XOR circuit 510 at time t3.

[0092] As shown in pattern 3 of FIG. 4, the output C of the XOR circuit 510 outputs a signal H at time t3.

[0093] That is, pattern 3 in FIG. 4 indicates that the sheet S is in a skewed state in the skew detection unit 5. In FIG.

[0094] 3A, when a signal H is input from the XOR circuit 510, the D flip-flop circuit 512 updates and stores the signal H at the timing of the rising edge of the signal H generated by the clock circuit 511. At time t3, the D flip-flop circuit 512 outputs the signal H. The D flip-flop circuit 512 continues to output the signal H until a signal L is input.

[0095] 4, the leading edge of the sheet S reaches the skew sensor 50b at time t4. Therefore, at time t4, the skew sensor 50b outputs a signal H. The signal H is input to the input B of the XOR circuit 510 at time t4.

[0096] As shown in pattern 3 of FIG. 4, the output C of the XOR circuit 510 continues to output the signal H even after time t3.

[0097] 3A receives a signal H from the D flip-flop circuit 512 at time t3, and stops the rotational driving of the motor 22. The motor 22 stops the rotational driving of the supply and conveyance roller 211. The supply and conveyance roller 211 stops conveying the sheet S downstream in the conveyance direction.

[0098] That is, when the skew of the sheet S is detected by the skew sensor 50, the conveyance of the sheet S is stopped before the sheet S reaches the heating unit 4.

[0099] 4, the leading edge of the sheet S reaches the skew sensor 50a at time t5. At time t5, the skew sensor 50a outputs a signal H. The signal H is input to the input A of the XOR circuit 510 at time t5.

[0100] 4, the leading edge of the sheet S reaches the skew sensor 50b at time t5. Therefore, at time t5, the skew sensor 50b outputs a signal H. The signal H is input to the input B of the XOR circuit 510 at time t5.

[0101] That is, pattern 4 in FIG. 4 indicates that the leading edge of the sheet S reaches the skew sensor 50a and the skew sensor 50b simultaneously at time t5.

[0102] Pattern 4 in FIG. 4 indicates that no skew occurs in the sheet S.

[0103] As shown in pattern 4 of FIG. 4, the output C of the XOR circuit 510 outputs a signal L at time t5.

[0104] 3(a), when signal L is input from XOR circuit 510, D flip-flop circuit 512 stores signal L at the timing of the rising edge of signal H by clock circuit 511. D flip-flop circuit 512 outputs signal L. D flip-flop circuit 512 continues outputting signal L until signal H is input.

[0105] 3A receives a signal L from the D flip-flop circuit 512, and rotates the motor 22. The motor 22 rotates the supply and conveyance roller 211. The supply and conveyance roller 211 conveys the sheet S downstream in the conveyance direction.

[0106] That is, when the skew detection unit 5 detects that the sheet S is not skewed, the sheet S or a sheet other than the sheet S being conveyed to the conveying path 210 is conveyed by the belt conveying roller 33 .

[0107] Next, the configuration of the heating unit 4 will be described with reference to Fig. 1 and further to Fig. 5(a) and (b). Fig. 5(a) is a diagram showing the configuration of the heating unit 4 and the relationship between the heating unit 4 and the skew detection unit 5. Fig. 5(b) is a diagram explaining the operation of the heating unit 4 based on the output of the skew detection unit 5.

[0108] As described above, the heating unit 4 heats the sheet S on which an image has been formed by the image forming unit 3.

[0109] As shown in FIG. 1 and FIG. 5( a ), the heating unit 4 includes a drive control unit 40 and a heater 41 .

[0110] The drive control unit 40 controls the heating unit 4. Specifically, the drive control unit 40 controls heating of the sheet S by the heater 41, or heating of a sheet other than the sheet S being conveyed on the conveying path 210. The drive control unit 40 controls the position of the heater 41.

[0111] The heating unit 4 has a home position where it can heat the sheet S.

[0112] The drive control unit 40 moves the heating unit 4 in a direction away from the sheet S from the home position to a retreat position based on the skew detection unit 5 detecting the skew of the sheet S.

[0113] The retreat position is, for example, a position where the sheet S or a sheet other than the sheet S being conveyed on the conveying path 210 is not excessively heated by the heating unit 4.

[0114] According to this embodiment, the skewed sheet S or sheets other than the sheet S being conveyed on the conveying path 210 can be more suitably prevented from being heated by the heating unit 4.

[0115] Next, the operation of the heating unit 4 based on the output of the skew detection unit 5 will be described with reference to FIGS. 5(a) and (b) in addition to FIG.

[0116] 4, when neither the skew sensor 50a nor the skew sensor 50b detects the sheet S, as shown in FIG. 5(b), the skew sensor 50a and the skew sensor 50b output a signal L. The signal L is input to the inputs A and B of the D flip-flop circuit 512.

[0117] The output C of the D flip-flop circuit 512 outputs the signal L.

[0118] 5(a), the drive control unit 40 controls the position G of the heater 41 based on a signal L. The heater 41 is controlled to be at a home position Gb.

[0119] That is, when the sheet S is not detected by the skew sensor 50 , the sheet S or a sheet other than the sheet S being conveyed to the conveying path 210 is heated by the heater 41 .

[0120] Next, as shown in pattern 2 in FIG. 4, skew sensor 50a does not detect the leading edge of sheet S. Skew sensor 50b detects the leading edge of sheet S. As shown in FIG. 5(b), skew sensor 50a outputs signal L. Skew sensor 50b outputs signal H. Signal L is input to input A of XOR circuit 510. Signal H is input to input B of XOR circuit 510.

[0121] The output C of the XOR circuit 510 outputs the H signal.

[0122] A signal H is input to an input C of the D flip-flop circuit 512 .

[0123] The output C of the D flip-flop circuit 512 outputs an H signal.

[0124] 5(a), the drive control unit 40 controls the position G of the heater 41 based on a signal H. The heater 41 is controlled to move to a retracted position Ga.

[0125] That is, when the skew of the sheet S is detected by the skew sensor 50, the transport of the sheet S is stopped so that the sheet S or sheets other than the sheet S being transported to the transport path 210 are not excessively heated by the heating section 4.

[0126] Next, as shown in pattern C of Fig. 4, the skew sensor 50a detects the leading edge of the sheet S. The skew sensor 50b does not detect the leading edge of the sheet S. As shown in Fig. 5(b), the skew sensor 50a outputs a signal H. The skew sensor 50b outputs a signal L. The signal H is input to an input A of the XOR circuit 510. The signal L is input to an input B of the XOR circuit 510.

[0127] The output C of the XOR circuit 510 outputs the H signal.

[0128] A signal H is input to an input C of the D flip-flop circuit 512 .

[0129] The output C of the D flip-flop circuit 512 outputs an H signal.

[0130] 5(a), the drive control unit 40 controls the position G of the heater 41 based on a signal H. The heater 41 is controlled to move to a retracted position Ga.

[0131] That is, when the skew of the sheet S is detected by the skew sensor 50, the transport of the sheet S is stopped so that the sheet S or sheets other than the sheet S being transported to the transport path 210 are not excessively heated by the heating section 4.

[0132] Next, as shown in pattern D of Fig. 4, the skew sensors 50a and 50b simultaneously detect the sheet S. As shown in Fig. 5(b), the skew sensors 50a and 50b simultaneously output a signal H. The signal H is input to the inputs A and B of the XOR circuit 510 simultaneously.

[0133] The output C of the XOR circuit 510 outputs the signal L.

[0134] A signal L is input to an input C of the D flip-flop circuit 512.

[0135] The output C of the D flip-flop circuit 512 outputs the signal L.

[0136] 5(a), the drive control unit 40 controls the position G of the heater 41 based on a signal L. The heater 41 is controlled to be at a home position Gb.

[0137] That is, when the skew of the sheet S is not detected by the XOR circuit 510, the sheet S or a sheet other than the sheet S being conveyed on the conveying path 210 is heated by the heating unit 4.

[0138] Next, the configurations of the sheet detection unit 6 and the evacuation unit 7 will be described with reference to Figs. 6(a) and (b) in addition to Fig. 1. Fig. 6(a) is a diagram showing the configurations of the sheet detection unit 6 and the evacuation unit 7. Fig. 6(a) further shows the relationship between the sheet detection unit 6 and the evacuation unit 7 and the skew detection unit 5. Fig. 6(b) is a diagram explaining the operation of the evacuation unit 7 based on the output of the skew detection unit 5.

[0139] As shown in FIG. 1 and FIG. 6( a ), the sheet detection unit 6 includes a sheet sensor 60 and a detection unit 61 .

[0140] As shown in FIG. 1, a sheet sensor 60 detects when an imaged sheet is in a position where it can be heated by heater 41 .

[0141] The sheet sensor 60 may have a similar configuration to the skew sensor 50 .

[0142] When the skew detection unit 5 detects the skew of the sheet S, the detection unit 61 detects that the sheet sensor 60 of the sheet detection unit 6 has detected the sheet on which an image has been formed.

[0143] A specific example of the detection unit 61 may be an AND circuit 610.

[0144] As shown in FIG. 1, the evacuation section 7 has a switching control section 70, a switching section 71, an evacuation storehouse 72, a third transport control section 73, and transport rollers 74.

[0145] The discharge section 8 includes a discharge roller 80 and a discharge tray 81 .

[0146] As shown in FIG. 1, the sheet detection unit 6 detects the presence or absence of an image-formed sheet on which an image has been formed by the image forming unit 3 in the heating unit 4.

[0147] The presence or absence in the heating section 4 means whether the image-formed sheet is in the range heated by the heat of the heating section 4 or not.

[0148] The evacuation section 7 evacuates the image-formed sheets.

[0149] The safe 72 stores sheets on which images have been formed.

[0150] The transport rollers 74 transport the image-formed sheet to the evacuation chamber 72 .

[0151] The sheet detection unit 6 outputs detection information when the skew detection unit 5 detects a skew and detects the presence of an image-formed sheet.

[0152] The evacuation section 7 drives the transport rollers 74 based on the detection information to transport the image-formed sheet to the evacuation storeroom 72 .

[0153] According to this embodiment, even if the conveyance of the sheet S is stopped due to skew, the sheet on which the image has been formed can be prevented from being excessively heated by the heating unit 4.

[0154] The discharge section 8 discharges the sheet on which the image has been formed.

[0155] The evacuation section 7 has a switching section 71 .

[0156] When the skew detection unit 5 detects the skew of the sheet S and detects that an image-formed sheet is present on the conveying path 210 including the heating unit 4, the switching unit 71 guides the sheet S or the image-formed sheet to an evacuation shelter 72.

[0157] The switching unit 71 guides the sheet S to the discharge unit 8 when the skew detection unit 5 does not detect the skew of the sheet S and detects that there is no image-formed sheet on the conveying path 210 including the heating unit 4.

[0158] According to this embodiment, based on whether the skew detection unit 5 detects the skew of the sheet S, the sheet S or the image-formed sheet on the conveying path 210 including the heating unit 4 can be switched and guided to the evacuation unit 72 or the discharge unit 8.

[0159] According to this embodiment, if the sheet S is skewed, the sheet S or the image-formed sheet is guided to an evacuation shelter 72, and the sheet S or the image-formed sheet that may have been overheated by the heat of the heating section 4 can be isolated in the evacuation shelter 72.

[0160] According to this embodiment, if the sheet S is not skewed, the sheet S or the sheet on which an image has been formed is suitably discharged to the discharge section 8.

[0161] Next, the operations of the sheet detection unit 6, the evacuation unit 7, and the discharge unit 8 will be described with reference to FIG. 1, FIG. 6(a) and FIG. 6(b).

[0162] As shown in pattern 1 of Fig. 4, when neither skew sensor 50a nor skew sensor 50b detects sheet S, as shown in Fig. 6(b), skew sensor 50a and skew sensor 50b output signal L. Signal L is input to inputs A and B of XOR circuit 510. Output C of XOR circuit 510 outputs signal L. Signal L is input to input C of D flip-flop circuit 512 and stored.

[0163] The output C of the D flip-flop circuit 512 outputs the signal L.

[0164] 1, when the sheet sensor 60 does not detect an image-formed sheet at the heater 41, as shown in Fig. 6(b), the sheet sensor 60 outputs a signal L. The signal L is input to an input D of the AND circuit 610 shown in Fig. 6(a).

[0165] The output E of the AND circuit 610 outputs the signal L.

[0166] The switching control unit 70 of the evacuation unit 7 sets the position J of the switching unit 71 based on the signal L. The switching control unit 70 sets the switching unit 71 to position Ja based on the signal L.

[0167] When the sheet sensor 60 detects an image-formed sheet at the heater 41, as shown in Fig. 6(b), the sheet sensor 60 outputs a signal H. The signal H is input to an input D of an AND circuit 610 shown in Fig. 6(a).

[0168] In this case as well, the output E of the AND circuit 610 outputs the signal L.

[0169] The switching control unit 70 of the evacuation unit 7 sets the position J of the switching unit 71 based on the signal L. The switching control unit 70 sets the switching unit 71 to position Ja based on the signal L.

[0170] As shown in FIG. 1, the third conveyance control unit 73 drives the conveyance rollers 74 and the discharge rollers 80 to rotate.

[0171] The switching section 71 guides the image-formed sheet to the discharge section 8 by switching the switching section 71 to the position Ja.

[0172] The transport roller 74 and the discharge roller 80 are driven to rotate to discharge the image-formed sheet to the discharge section 8. The discharge tray 81 stores the image-formed sheet.

[0173] That is, when the skew sensor 50 does not detect the sheet S, the switching control unit 70 switches the switching unit 71 to position Ja regardless of whether the sheet sensor 60 detects the presence or absence of an image-formed sheet at the heater 41. When an image-formed sheet is present at the heater 41, the image-formed sheet is discharged to the discharge tray 81.

[0174] Next, as shown in pattern 2 in Fig. 4, the skew sensor 50b detects the leading edge of the sheet S before the skew sensor 50a. After that, the skew sensor 50a detects the leading edge of the sheet S. As shown in Fig. 6(b), the skew sensor 50b outputs a signal H. The skew sensor 50a outputs a signal L.

[0175] A signal L is input to an input A of the XOR circuit 510. A signal H is input to an input B of the XOR circuit 510.

[0176] The output C of the XOR circuit 510 outputs a signal H. The signal H is input to the D flip-flop circuit 512 and stored therein.

[0177] The output C of the D flip-flop circuit 512 outputs an H signal.

[0178] A signal H is input to the input C of the AND circuit.

[0179] 1, when the sheet sensor 60 does not detect an image-formed sheet at the heater 41, as shown in Fig. 6(b), the sheet sensor 60 outputs a signal L. The signal L is input to an input D of the AND circuit 610 shown in Fig. 6(a).

[0180] The output E of the AND circuit 610 outputs the signal L.

[0181] The switching control unit 70 of the evacuation unit 7 sets the position J of the switching unit 71 based on the signal L. The switching control unit 70 sets the switching unit 71 to position Ja based on the signal L.

[0182] As shown in FIG. 1, the third conveyance control unit 73 drives the conveyance rollers 74 and the discharge rollers 80 to rotate.

[0183] When the switching section 71 is switched to the position Ja, the sheet on which the image has been formed is guided to the discharge section 8.

[0184] The transport roller 74 and the discharge roller 80 are driven to rotate to discharge the image-formed sheet to the discharge section 8. The discharge tray 81 stores the image-formed sheet.

[0185] 1, when the sheet sensor 60 detects an image-formed sheet at the heater 41, the sheet sensor 60 outputs a signal H as shown in Fig. 6(b). The signal H is input to an input D of an AND circuit 610 shown in Fig. 6(a).

[0186] The output E of the AND circuit 610 outputs the signal H.

[0187] Based on the signal H, the switching control unit 70 of the evacuation unit 7 sets the position J of the switching unit 71 to the position Jb.

[0188] As shown in FIG. 1, the third conveyance control unit 73 drives the conveyance rollers 74 to rotate.

[0189] The switching unit 71 guides the image-formed sheet to the evacuation chamber 72 by switching to the position Jb.

[0190] The sheet on which the image has been formed is transported by transport rollers 74 , guided to a switching section 71 , and stored in a safe bin 72 .

[0191] That is, when the skew sensor 50 detects the skew of the sheet S, but the sheet sensor 60 does not detect an image-formed sheet at the heater 41, the switching unit 71 is switched to position Ja. When the sheet sensor 60 detects an image-formed sheet at the heater 41, the switching unit 71 is switched to position Jb. Then, the image-formed sheet that was at the heater 41 is discharged to the discharge tray 81.

[0192] Next, as shown in pattern 3 of Fig. 4, when the skew sensor 50a detects the leading edge of the sheet S first, and then the skew sensor 50b detects the leading edge of the sheet S, the skew sensor 50a outputs a signal H as shown in Fig. 6(b). The skew sensor 50b outputs a signal L.

[0193] A signal H is input to an input A of the XOR circuit 510. A signal L is input to an input B of the XOR circuit 510.

[0194] The output C of the XOR circuit 510 outputs a signal H. The signal H is input to the D flip-flop circuit 512 and stored therein.

[0195] The output C of the D flip-flop circuit 512 outputs an H signal.

[0196] A signal H is input to the input C of the AND circuit.

[0197] 1, when the sheet sensor 60 does not detect an image-formed sheet at the heater 41, as shown in Fig. 6(b), the sheet sensor 60 outputs a signal L. The signal L is input to an input D of the AND circuit 610 shown in Fig. 6(a).

[0198] The output E of the AND circuit 610 outputs the signal L.

[0199] Based on the signal L, the switching control unit 70 of the evacuation unit 7 sets the switching unit 71 to position Ja.

[0200] As shown in FIG. 1, the third conveyance control unit 73 may drive the conveyance roller 74 and the discharge roller 80 to rotate.

[0201] 1, when the sheet sensor 60 detects an image-formed sheet at the heater 41, the sheet sensor 60 outputs a signal H as shown in Fig. 6(b). The signal H is input to an input D of an AND circuit 610 shown in Fig. 6(a).

[0202] The output E of the AND circuit 610 outputs the signal H.

[0203] Based on the signal H, the switching control unit 70 of the evacuation unit 7 sets the position J of the switching unit 71 to the position Jb.

[0204] As shown in FIG. 1, the third conveyance control unit 73 drives the conveyance rollers 74 to rotate.

[0205] When the switching unit 71 is switched to the position Jb, the image-formed sheet is guided to the evacuation chamber 72 .

[0206] The sheet on which the image has been formed is transported by transport rollers 74 , guided to a switching section 71 , and stored in a safe bin 72 .

[0207] That is, when the skew sensor 50 detects the skew of the sheet S, but the sheet sensor 60 does not detect an image-formed sheet at the heater 41, the switching unit 71 is switched to position Ja. When the sheet sensor 60 detects an image-formed sheet at the heater 41, the switching unit 71 is switched to position Jb. Then, the image-formed sheet that was at the heater 41 is discharged to the discharge tray 81.

[0208] Next, when the skew sensors 50a and 50b simultaneously detect the leading edge of the sheet S as shown in pattern 4 of FIG. 4, the skew sensors 50a and 50b simultaneously output signals H as shown in FIG. 6(b).

[0209] A signal H is input to inputs A and B of the XOR circuit 510 at the same time.

[0210] The output C of the XOR circuit 510 outputs a signal L. The signal L is input to the D flip-flop circuit 512 and stored therein.

[0211] The output C of the D flip-flop circuit 512 outputs the signal L.

[0212] A signal L is input to an input C of the AND circuit.

[0213] 1, when the sheet sensor 60 does not detect an image-formed sheet at the heater 41, as shown in Fig. 6(b), the sheet sensor 60 outputs a signal L. The signal L is input to an input D of the AND circuit 610 shown in Fig. 6(a).

[0214] The output E of the AND circuit 610 outputs the signal L.

[0215] Based on the signal L, the switching control unit 70 of the evacuation unit 7 sets the switching unit 71 to position Ja.

[0216] As shown in FIG. 1, the third conveyance control unit 73 may drive the conveyance roller 74 and the discharge roller 80 to rotate.

[0217] The sheet S detected by the skew detection unit 5 may be transported by a transport roller 74 and a discharge roller 80.

[0218] The switching section 71 may guide the sheet S to a discharge tray 81 .

[0219] The sheet S may be transported by the transport rollers 74 and the discharge rollers 80 , guided to the switching section 71 , and discharged onto the discharge tray 81 .

[0220] 1, when the sheet sensor 60 detects an image-formed sheet at the heater 41, the sheet sensor 60 outputs a signal H as shown in Fig. 6(b). The signal H is input to an input D of an AND circuit 610 shown in Fig. 6(a).

[0221] The output E of the AND circuit 610 outputs the signal L.

[0222] Based on the signal L, the switching control unit 70 of the evacuation unit 7 sets the position J of the switching unit 71 to the position Ja.

[0223] As shown in FIG. 1, the third conveyance control unit 73 drives the conveyance rollers 74 and the discharge rollers 80 to rotate.

[0224] The switching section 71 guides the image-formed sheet and the sheet S to the discharge tray 81 by switching to the position Ja.

[0225] The image-formed sheet and the sheet S are transported by the transport rollers 74 and the discharge rollers 80 , guided to the switching section 71 , and stored in the discharge tray 81 .

[0226] That is, when the skew sensor 50 does not detect the skew of the sheet S, the switching unit 71 is switched to position Ja regardless of whether the sheet sensor 60 detects an image-formed sheet at the heater 41. When the sheet sensor 60 detects an image-formed sheet at the heater 41, the switching unit 71 is switched to position Ja. Then, the sheet S and the image-formed sheet that was at the heater 41 are discharged to the discharge tray 81. When the sheet sensor 60 does not detect an image-formed sheet at the heater 41, the switching unit 71 is switched to position Ja. Then, the sheet S is discharged to the discharge tray 81.

[0227] Next, an image forming method according to this embodiment will be described with reference to Figures 7 and 8. Figures 7 and 8 are flow charts showing an image forming processing method according to the embodiment of the present invention.

[0228] As shown in FIG. 7, the flowchart includes steps S10 to S16.

[0229] 7, the feeding and conveying section 2 feeds and conveys the sheet S. The process proceeds to step S12.

[0230] In step S12, the image forming section 3 forms an image on the sheet S fed and conveyed by the feeding and conveying section 2. The process proceeds to step S14.

[0231] In step S14, the heating section 4 heats the sheet S on which an image has been formed by the image forming section 3. The process proceeds to step S16.

[0232] In step S16, the skew detection unit 5 detects the skew of the sheet S before the sheet S approaches the heating unit 4. Then, the process ends.

[0233] Next, as shown in FIG. 8, the flowchart includes steps S20 to S56.

[0234] 8, the skew detection unit 5 detects the skew of the sheet S. If the skew detection unit 5 detects the skew (Yes in step S20), the process proceeds to step S22. If the skew detection unit 5 does not detect the skew (No in step S20), the process proceeds to step S50.

[0235] If the skew detection unit 5 detects a skew (Yes in step S20), in step S22, the first conveyance control unit 23 stops driving the motor 22 and stops conveyance of the sheet S by the feed conveyance roller 211. The process proceeds to step S24.

[0236] In step S24, the drive control unit 40 retreats the heater 41 to position Gb. The process proceeds to step S26.

[0237] In step S26, the sheet sensor 60 detects that an image-formed sheet is located immediately below (close to) the heater 41. If the sheet sensor 60 detects an image-formed sheet (Yes in step S26), the process proceeds to step S28. If the sheet sensor 60 does not detect an image-formed sheet (No in step S26), the process proceeds to step S40.

[0238] When the sheet sensor 60 detects an image-formed sheet (Yes in step S26), in step S28, the switching control unit 70 switches the switching unit 71 to position Jb. That is, the switching control unit 70 switches the switching unit 71 so that the image-formed sheet is guided to the evacuation room 72. The process proceeds to step S30.

[0239] In step S30, the third conveyance control unit 73 rotates the conveyance rollers 74 to convey the image-formed sheet to the evacuation room 72. Then, the process ends.

[0240] If the sheet sensor 60 does not detect an image-formed sheet (No in step S26), in step S40, the switching control unit 70 switches the switching unit 71 to position Ja. That is, the switching control unit 70 switches the switching unit 71 so that the sheet S is guided to the discharge unit 8. The discharge rollers 80 transport the sheet S to the discharge tray 81. Then, the process ends.

[0241] Next, if the skew detection unit 5 does not detect a skew (No in step S20), in step S50, the sheet detection unit 6 detects that an image-formed sheet is retained in the heater 41. If the sheet detection unit 6 detects that an image-formed sheet is retained in the heater 41 (Yes in step S50), the process proceeds to step S52. If the sheet detection unit 6 does not detect that an image-formed sheet is retained in the heater 41 (No in step S50), the process proceeds to step S42.

[0242] When the sheet sensor 60 detects that an image-formed sheet is retained at the heater 41 (Yes in step S50), the drive control unit 40 retreats the heater 41 to position Gb in step S52. The process proceeds to step S54.

[0243] In step S54, the switching control unit 70 switches the switching unit 71 to the position Jb. That is, the switching control unit 70 switches the switching unit 71 so that the image-formed sheet is guided to the evacuation storeroom 72. The process proceeds to step S56.

[0244] In step S56, the third conveyance control unit 73 rotates the conveyance roller 74 to convey the image-formed sheet to the evacuation room 72. Then, the process ends.

[0245] If the sheet sensor 60 does not detect that an image-formed sheet is retained at the heater 41 (No in step S50), in step S42, the sheet S is discharged to the discharge section 8. Then, the process ends.

[0246] The embodiments of the invention have been described above with reference to the drawings. However, the present invention is not limited to the above embodiments, and can be implemented in various forms without departing from the spirit of the present invention. The drawings are mainly schematic illustrations of the respective components for ease of understanding, and the number of each component shown in the drawings may differ from the actual number due to the convenience of drawing. Furthermore, the components shown in the above embodiments are merely examples, and are not particularly limited, and various modifications are possible without substantially departing from the effects of the present invention. [Industrial Applicability]

[0247] The present invention can be used in the fields of image forming apparatuses and image forming methods. [Explanation of symbols]

[0248] 1. Image forming device 2. Feeding and conveying section 211 Feeding roller 3. Image forming section 4 Heating section 41 Heater 5 Skew detection section 50a skew sensor 50b Skew Sensor 51 Detection unit 510 XOR circuit 511 Clock Circuit 512 D Flip Flop 6 Sheet detection unit 60 Sheet Sensor 7 Evacuation Department 71 Switching section 72 Refuge 8 Discharge section

Claims

1. a feeding and conveying unit that feeds and conveys a sheet; an image forming unit that forms an image on the sheet fed and conveyed by the feeding and conveying unit; a heating section that heats the sheet on which an image has been formed by the image forming section; a skew detection unit that is disposed upstream of the heating unit in a conveying direction and detects a skew of the sheet before the sheet approaches the heating unit; An image forming apparatus comprising:

2. The supply / conveyance unit has a first conveyance control unit that controls driving of the supply / conveyance unit, The image forming apparatus according to claim 1 , wherein the first conveyance control unit stops driving the supply / conveyance unit before the sheet approaches the heating unit based on the detection of the skew.

3. The heating unit has a drive control unit that controls the heating unit, the heating unit has a home position at which the sheet can be heated; 3. The image forming apparatus according to claim 1, wherein the drive control section moves the heating section from the home position in a direction away from the sheet based on the detection of the skew by the skew detection section.

4. a sheet detection unit that detects the presence or absence of an image-formed sheet in the heating unit on which an image is formed by the image forming unit; an evacuation section for evacuating the image-formed sheet; Further equipped with The evacuation section includes: a safe for storing the image-formed sheets; a conveying roller that conveys the image-formed sheet to the evacuation shelter; having the sheet detection unit outputs detection information when the skew detection unit detects the skew and detects the presence of the image-formed sheet; The image forming apparatus according to claim 1 , wherein the evacuation section drives the transport roller based on the detection information to transport the image-formed sheet to the evacuation shelter.

5. a discharge section for discharging the image-formed sheet, The evacuation section has a switching section, The switching unit is When the skew detection unit detects the skew and detects the presence of the image-formed sheet, the image-formed sheet is guided to the evacuation shelter; 5. The image forming apparatus according to claim 4, wherein when the skew detection section does not detect the skew and detects that the image-formed sheet is not present, the image-formed sheet is guided to the discharge section.

6. A feeding and conveying unit feeds and conveys a sheet; An image forming unit forms an image on the sheet fed and conveyed by the feeding and conveying unit; A heating section heats the sheet on which an image has been formed by the image forming section; a skew detection unit disposed upstream of the heating unit in a conveying direction detects a skew of the sheet before the sheet approaches the heating unit; An image forming method comprising:

Images