Image formation apparatus

Abstract

To provide an image formation apparatus capable of efficiently determining a jam of a recording medium.SOLUTION: An image formation apparatus includes an image formation unit 25, a heating unit 30, an acquisition unit 51, a setting unit 52, a time measurement unit 53, and a determination unit 54. The image formation unit 25 forms an image on a sheet P. The heating unit 30 heats the sheet P on which the image has been formed. The acquisition unit 51 acquires medium information indicating information related to a temperature change when the sheet P is heated. The setting unit 52 sets a determination threshold time T on the basis of the medium information of the sheet P. The time measurement unit 53 measures an elapsed time t that has elapsed since the sheet P is carried into the heating unit 30. The determination unit 54 determines a jam of the sheet P in the heating unit 30 on the basis of the elapsed time t and the determination threshold time T.SELECTED DRAWING: Figure 6

Description

[Technical field]

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

[0002] The image forming apparatus described in Patent Document 1 includes an image forming function that applies ink to a recording medium, i.e., paper, to form an image, and a drying device. The drying device has a first shutter unit that closes the inlet, a second shutter unit that closes the outlet, and a third shutter unit that shuts off the heat source when a paper jam occurs. A paper jam is determined by comparing the count value of the inlet sensor with the count value of the outlet sensor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2020-128050 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the image forming apparatus described in Patent Document 1, there is a risk that a jam of the recording medium cannot be efficiently determined.

[0005] The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide an image forming apparatus that can efficiently determine whether a recording medium has become jammed. [Means for solving the problem]

[0006] The image forming apparatus according to the present invention comprises an image forming unit, a heating unit, an acquisition unit, a setting unit, a time measurement unit, and a judgment unit. The image forming unit forms an image on a recording medium. The heating unit heats the recording medium on which the image has been formed. The acquisition unit acquires medium information indicating information regarding a temperature change when the recording medium is heated. The setting unit sets a judgment threshold time based on the medium information of the recording medium. The time measurement unit measures the elapsed time that has elapsed since the recording medium was transported into the heating unit. The judgment unit judges a jam of the recording medium in the heating unit based on the elapsed time and the judgment threshold time. Effect of the Invention

[0007] According to the image forming apparatus of the present invention, a jam of the recording medium can be efficiently determined. [Brief description of the drawings]

[0008] [Figure 1] 1 is a diagram showing a configuration of an image forming apparatus according to a first embodiment. [Diagram 2] FIG. 4 is a diagram showing a configuration of a second transport device. [Diagram 3] FIG. 1 is a block diagram illustrating an image forming apparatus. [Figure 4] FIG. 11 is a diagram showing a first conversion table for converting the type and moisture content into a score. [Diagram 5] FIG. 13 is a diagram showing a second conversion table for converting a score into a judgment threshold time. [Figure 6] 13 is a flowchart showing a sheet jamming determination process. [Figure 7] FIG. 11 is a diagram showing a configuration of an image forming apparatus according to a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, 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.

[0010] First, an image forming apparatus 1 will be described with reference to Fig. 1 and Fig. 2. Fig. 1 is a diagram showing the configuration of the image forming apparatus 1 according to the present embodiment. Fig. 2 is a diagram showing the configuration of a second conveying device 3 according to the present embodiment.

[0011] As shown in FIG. 1, the image forming apparatus 1 includes a first conveying device 2, a second conveying device 3, a third conveying device 4, and a control unit 5.

[0012] The second conveying device 3 is connected to the first conveying device 2. The third conveying device 4 is connected to the second conveying device 3. The second conveying device 3 is connected to the downstream side of the conveying direction of the sheet P relative to the first conveying device 2. The third conveying device 4 is connected to the downstream side of the conveying direction of the sheet P relative to the second conveying device 3. The sheet P corresponds to, for example, a "recording medium."

[0013] The first conveying device 2 acquires image data from a document. Alternatively, the first conveying device 2 acquires image data from an external server or terminal. The first conveying device 2 forms an image on a sheet P based on the image data and outputs the image. The first conveying device 2 may be a device that combines an image data transmission / reception function, an image reading function, and an image forming function. The first conveying device 2 has functions such as a scanner, a printer, a copier, a telephone, and a facsimile.

[0014] The server stores the data and provides the corresponding data when requested via a communication line.

[0015] The first conveying device 2 forms an image on the sheet P.

[0016] The first conveying device 2 has a feeding section 20, a feeding section 21, a conveying section 22, a conveying section 23, a conveying section 24, an image forming section 25, a conveying belt 26, and a double-sided conveying path 27.

[0017] The feeding section 20 stores the sheets P and feeds the sheets P.

[0018] The transport section 22 includes a transport roller 22A. The transport section 22 transports the sheet P fed from the feeding section 20 toward the image forming section 25 by the transport roller 22A.

[0019] The conveying section 23 conveys the sheet P manually fed from the feeding section 21 toward the image forming section 25.

[0020] The conveying section 24 conveys the sheet P to the second conveying device 3.

[0021] The image forming unit 25 forms an image on the transported sheet P. When the first transport device 2 is an inkjet printer, the image forming unit 25 has, for example, an ink tank, a head, and a nozzle.

[0022] The ink cartridges and ink tanks store water-based inks of various colors, for example, Y (yellow), M (magenta), C (cyan), and Bk (black).

[0023] The pump supplies ink from the ink tank to the head.

[0024] A large number of nozzles are arranged in the head. Ink of a color corresponding to the image data is supplied from an ink tank to the head based on the image data. The ink is ejected from the nozzles toward the sheet P.

[0025] The conveyor belt 26 is disposed opposite the nozzles of the head, and conveys the sheet P. An image is formed on the sheet P conveyed by the conveyor belt 26 with ink ejected from the nozzles of the head.

[0026] The double-sided conveying path 27 inverts the printed side of the sheet P. The double-sided conveying path 27 conveys the sheet P with the inverted printed side to the image forming unit 25. The double-sided conveying path 27 changes the state of the sheet P from a state in which the printed side is face-up to a state in which the printed side is face-down.

[0027] 1, the third conveying device 4 discharges the sheet P conveyed from the second conveying device 3. The third conveying device 4 may include a paper discharge tray 40 for accommodating the discharged sheet P.

[0028] As shown in FIG. 2, the second conveying device 3 includes a heating section 30, a conveying section 31, a conveying roller 32, a switching section 33, a first drum conveying section 34, a second drum conveying section 35, a detection section 61, a first detection section 62, and a second detection section 63.

[0029] The heating section 30 heats the sheet P on which an image is formed. The heating section 30 has a heater 30A and a support section 30B. The heating section 30 is partitioned into a predetermined region including the heater 30A and the support section 30B.

[0030] The heater 30A has a heat source for heating air and a blower for blowing out the heated air. The heater 30A supplies radiant heat to the sheet P conveyed into the second conveying device 3.

[0031] The support portion 30B has, for example, an endless belt stretched between the driving roller 30a and the driven roller 30b. The support portion 30B supports the sheet P from below with the endless belt. The support portion 30B transports the heated sheet P with the endless belt.

[0032] As shown in FIG. 2, the conveying section 31 includes a reversing conveying path 31A, a reversing conveying path 31B, a reversing conveying path 31C, a first evacuation conveying path 31D, a first evacuation conveying path 31E, a first U-turn conveying path 31F, a first discharge conveying path 31G, and a first discharge conveying path 31H.

[0033] The sheet P conveyed from the first conveying device 2 is reversed toward the first conveying device 2 by the reverse conveying path 31A, the reverse conveying path 31B, and the reverse conveying path 31C.

[0034] The reverse transport path 31A is formed extending in the M direction (arrow left direction) from the transport section 24 of the first transport device 2. The reverse transport path 31A includes a support section 30B, a first transport roller 32A, and a second transport roller 32B.

[0035] The first transport roller 32A sends the sheet P to the support unit 30B. The first transport roller 32A is disposed at a position upstream of the heating unit 30. The first transport roller 32A receives the sheet P from the transport unit 24 via a feed roller 24A. The first transport roller 32A sends the sheet P received from the roller 24A in the M direction.

[0036] The second transport roller 32B receives the sheet P from the support unit 30B. The second transport roller 32B is disposed at a downstream position from the heating unit 30. The second transport roller 32B sends the sheet P received from the support unit 30B in the M direction.

[0037] That is, the support section 30B receives the sheet P from the first transport rollers 32A. The support section 30B sends out the sheet P to the second transport rollers 32B. The sheet P discharged from the transport section 24 of the first transport device 2 is transported in the M direction on the reverse transport path 31A with the heating section 30 interposed therebetween.

[0038] The reversing conveying path 31B is connected to the reversing conveying path 31A, and branches off from the reversing conveying path 31A in the N direction (for example, from the arrow downward to the arrow right direction) into a first discharge conveying path 31H. The sheet P conveyed in the M direction on the reversing conveying path 31A is conveyed in the N direction on the reversing conveying path 31B while being reversed.

[0039] The reversing conveying path 31C is connected to the reversing conveying path 31B. The sheet P reversed in the reversing conveying path 31B continues to be conveyed in the N direction on the reversing conveying path 31C.

[0040] The first evacuation conveying path 31D and the first evacuation conveying path 31E are connected to the reversing conveying path 31A, the reversing conveying path 31B, and the reversing conveying path 31C. The sheet P is conveyed through the reversing conveying path 31A, the reversing conveying path 31B, and the reversing conveying path 31C, and then conveyed to the first evacuation conveying path 31D and the first evacuation conveying path 31E.

[0041] The first evacuation conveying path 31D is connected to the reversing conveying path 31C at a point where the switching unit 33C is disposed. The first evacuation conveying path 31D extends to the first drum conveying unit 34 in the direction of the arrow O (for example, to the right of the arrow).

[0042] The first evacuation conveying path 31E is connected to the first evacuation conveying path 31D. The first evacuation conveying path 31E forms a part of the first drum conveying section 34. A part of the first evacuation conveying path 31D and the first evacuation conveying path 31E may form the first drum conveying section 34. The sheet P is conveyed in the direction of the arrow O from the first evacuation conveying path 31D to the first evacuation conveying path 31E.

[0043] The first U-turn transport path 31F branches off between the first evacuation transport path 31D and the first evacuation transport path 31E.

[0044] The first drum transport section 34 switches back the sheet P with its face down. Face down is a state in which the print surface of the sheet P faces downward. The first drum transport section 34 includes a first evacuation transport path 31D, a first evacuation transport path 31E, and a first U-turn transport path 31F. The sheet P transported to the first drum transport section 34 is evacuated to the first evacuation transport path 31E.

[0045] The sheet P switched back from the first retreat conveying path 31E is conveyed along the first U-turn conveying path 31F toward the first conveying device 2. The sheet P conveyed to the first conveying device 2 has the non-printed side printed, and is double-sided printed.

[0046] The first evacuation transport path 31D and the first evacuation transport path 31E have a drum shape.

[0047] Next, as shown in FIG. 2, the conveying section 31 further has a first discharge conveying path 31G, a first discharge conveying path 31H, a second evacuation conveying path 31I, a second evacuation conveying path 31J, a second U-turn conveying path 31K, and a second U-turn conveying path 31L.

[0048] The first discharge conveying path 31G and the first discharge conveying path 31H are connected to the third conveying device 4. The third conveying device 4 is disposed on the opposite side of the first conveying device 2 with respect to the second conveying device 3.

[0049] The first discharge conveying path 31G and the first discharge conveying path 31H branch off from the first U-turn conveying path 31F. The sheet P is switched back and conveyed in the direction of the arrow Q from the first retreat conveying path 31E towards the third conveying device 4.

[0050] The first discharge conveying path 31G is connected to the first discharge conveying path 31H. The first discharge conveying path 31H extends to the third conveying device 4 shown in FIG.

[0051] The second drum transport section 35 processes the next sheet P while the first drum transport section 34 processes the sheet P. The second drum transport section 35 switches back the sheet P face-down, similar to the first drum transport section 34. The second drum transport section 35 includes a second evacuation transport path 31I, a second evacuation transport path 31J, and a second U-turn transport path 31K. The second evacuation transport path 31J is continuous with the second evacuation transport path 31I, and transports the sheet P in the direction of the arrow R.

[0052] The second evacuation conveying path 31I is continuous with the reversing conveying path 31C. The second evacuation conveying path 31I branches off from the first evacuation conveying path 31D. The second evacuation conveying path 31I retracts the sheet P conveyed by the reversing conveying path 31A, the reversing conveying path 31B, and the reversing conveying path 31C.

[0053] The second U-turn conveying path 31K and the second U-turn conveying path 31L branch off from the second evacuation conveying path 31I and the second evacuation conveying path 31J at a point where the switching unit 33F is disposed.

[0054] The second U-turn conveying path 31K and the second U-turn conveying path 31L convey the sheet P switched back from the second retreat conveying path 31J toward the first conveying device 2.

[0055] The first discharge conveying path 31G and the first discharge conveying path 31H branch off from the second U-turn conveying path 31K and the second U-turn conveying path 31L at a point where the switching unit 33E is disposed.

[0056] The first discharge conveying path 31G and the first discharge conveying path 31H convey the sheet P switched back from the second retreat conveying path 31J toward the third conveying device 4.

[0057] The second evacuation conveying path 31I and the second evacuation conveying path 31J have a drum shape.

[0058] The detection unit 61 detects the sheet P. As shown in FIG 2, the detection unit 61 is disposed at an upstream position of the support unit 30B. Specifically, the detection unit 61 is disposed between the first conveying device 2 and the second conveying device 3.

[0059] The detection unit 61 detects medium information of the sheet P. Specifically, the detection unit 61 is a media sensor. The medium information includes information on the type of the sheet P and information on the moisture content of the sheet P.

[0060] The type of sheet P is, for example, its thickness and material. The detection unit 61 measures the thickness by, for example, irradiating the sheet P with X-rays and measuring the amount of light transmitted through the sheet P. Note that the method for measuring the thickness of the sheet P is not limited to irradiating with X-rays, and the amount of light transmitted through the sheet P may be measured by irradiating the sheet P with infrared rays. Note that instead of measuring the amount of light transmitted through the sheet P, the amount of light reflected from the sheet P may be measured. In this case, the thickness of the sheet P is measured based on the amount of light reflected from the sheet P.

[0061] Furthermore, the detection unit 61, for example, supplies microwaves to the sheet P and measures the moisture content based on the amount of microwaves absorbed by the sheet P. Instead of microwaves, the moisture content of the sheet P may be measured via capacitance based on the electrical resistance value of the sheet P. The medium information is not limited to the thickness and moisture content of the sheet P. The medium information may include the material of the sheet P, and the medium information may be any one of these.

[0062] The first detection unit 62 and the second detection unit 63 detect the sheet P being transported. The first detection unit 62 and the second detection unit 63 are disposed at a position spaced above the transport unit 31. The first detection unit 62 detects that the sheet P is transported into the heating unit 30. The first detection unit 62 is disposed, for example, between the detection unit 61 and the heating unit 30. The second detection unit 63 detects that the sheet P is transported out of the heating unit 30. The second detection unit 63 is disposed, for example, between the heating unit 30 and the second transport roller 32B.

[0063] Next, the control system of the image forming apparatus 1 will be described with reference to Fig. 3 to Fig. 5. Fig. 3 is a block diagram showing the image forming apparatus 1 according to the present embodiment. Fig. 4 is a diagram showing a first conversion table T1 for converting the type and moisture content into a score. Fig. 5 is a diagram showing a second conversion table T2 for converting the score into a judgment threshold time.

[0064] 3, the image forming apparatus 1 further includes a storage unit 71. The storage unit 71 is configured with a RAM (Random Access Memory) and a ROM (Read Only Memory). Specifically, the storage unit 71 includes a main storage device such as a semiconductor memory, and an auxiliary storage device such as a semiconductor memory, a solid state drive, and / or a hard disk drive.

[0065] The storage unit 71 stores a control program for controlling the operation of each unit of the image forming apparatus 1. The storage unit 71 stores setting information input by operating an operation panel (not shown). As shown in Fig. 4 and Fig. 5, the storage unit 71 stores a first conversion table T1 and a second conversion table T2.

[0066] As shown in FIG. 4, the first conversion table T1 specifies the type of sheet P and the score corresponding to this type. An example of types A to J of sheet P will be described. For example, types A to J are set so that the temperature rising tendency gradually decreases. That is, type A has the greatest temperature rising tendency, and type J has the smallest temperature rising tendency. In the first conversion table T1, the greater the temperature rising tendency, the smaller the type score P1. Therefore, type A has the smallest type score P1, and type J has the largest type score P1. The correlation between type A and type score P1 is preset by experience and experimentation.

[0067] The first conversion table T1 specifies the moisture content of the sheet P and the score corresponding to this moisture content. For example, the sheets P are divided into 1% moisture content groups, and examples of sheets P with moisture content of 0-1% to sheets P with moisture content of 9-10% are described. That is, sheets P with moisture content of 0-1% have the greatest tendency to increase in temperature, and sheets P with moisture content of 9-10% have the least tendency to increase in temperature. In the first conversion table T1, the greater the tendency to increase in temperature, the smaller the moisture content score P2. Therefore, sheets P with moisture content of 0-1% have the smallest moisture content score P2, and sheets P with moisture content of 9-10% have the largest moisture content score P2. The correlation between the moisture content and the moisture content score P2 is preset by experience and experiment.

[0068] As shown in Fig. 5, the second conversion table T2 specifies a total score TP, which is the sum of a type score P1 of the sheet P and a moisture content score P2 of the sheet P, and a judgment threshold time T corresponding to this total score TP. When the total score TP is large, the judgment threshold time T is large. In this embodiment, when the total score TP is 11 or more, the judgment threshold time T is maintained at 190 (msec). However, when the total score TP is 11 or more, it is not limited to being maintained at 190 (msec). The judgment threshold time T may increase as the total score TP increases.

[0069] 3, the control unit 5 executes a control program stored in the storage unit 71 to control the image forming unit 25, the heating unit 30, and the storage unit 71. The control unit 5 is a hardware circuit. The hardware circuit includes a processor such as a CPU (Central Processing Unit). Note that an ASIC (Application Specific Integrated Circuit) may be used instead of the CPU.

[0070] 3, the control unit 5 has an acquisition unit 51, a setting unit 52, a time measurement unit 53, and a determination unit 54. The processor of the control unit 5 executes a computer program stored in the memory unit 71 to function as each operating unit.

[0071] The acquisition unit 51 acquires medium information. The medium information indicates information related to a temperature change when the sheet P is heated. The medium information is, for example, the thickness of the sheet P, the material of the sheet P, and the moisture content of the sheet P. The acquisition unit 51 inputs the detection result of the sheet P from the detection unit 61.

[0072] The setting unit 52 sets the determination threshold time T. The setting unit 52 sets the determination threshold time T based on the medium information of the sheet P. Specifically, the setting unit 52 sets the determination threshold time T based on the medium information of the sheet P, a first conversion table T1, and a second conversion table T2.

[0073] The time measurement unit 53 measures the elapsed time t that has elapsed since the sheet P was carried into the heating unit 30. The time measurement unit 53 receives an input of the detection result of the sheet P from the first detection unit 62. The time measurement unit 53 obtains the elapsed time t that has elapsed since the sheet P was carried into the heating unit 30 based on the detection result of the first detection unit 62.

[0074] The determination unit 54 determines whether the sheet P is jammed. The determination unit 54 determines whether the sheet P is jammed in the heating unit 30 based on the elapsed time t and the determination threshold time T. Specifically, the determination unit 54 determines whether the sheet P is jammed when the elapsed time t is greater than the determination threshold time T. The determination unit 54 determines whether the sheet P is jammed in the heating unit 30 based on the elapsed time t from when the sheet P is carried into the heating unit 30 until it is carried out, and the determination threshold time T set based on the sheet P indicating information on the temperature change when the sheet P is heated. Therefore, it is possible to efficiently determine whether the sheet P is jammed in the heating unit 30 according to the temperature characteristics of the sheet P.

[0075] For example, for a sheet P with a large tendency for its temperature to rise, priority is given to avoiding deterioration of the sheet P, and a jam of the sheet P is determined in a short time. For a sheet P with a small tendency for its temperature to rise, priority is given to accuracy in determining whether the sheet P is jammed, and a sufficient amount of time is spent determining whether the sheet P is jammed. Therefore, a jam of the sheet P can be determined early while suppressing erroneous detection of a jam of the sheet P. As a result, a jam of the sheet P can be determined efficiently.

[0076] The medium information includes information regarding the type of sheet P and information regarding the moisture content of the sheet P. The medium information can include information regarding the type and information regarding the moisture content, which are greatly affected by the rising trend of the temperature. Therefore, the determination threshold time T can be set according to the rising trend of the temperature.

[0077] Next, the control unit 5 will be described in detail with reference to FIG. 3 to FIG.

[0078] The acquisition unit 51 generates medium information of the sheet P based on the detection result of the detection unit 61. The determination threshold time T can be set directly from the sheet P. This improves the accuracy of the determination threshold time T. As a result, a jam in the sheet P can be detected early while suppressing erroneous detection of a jam in the sheet P.

[0079] As shown in Fig. 4, in the first conversion table T1, the greater the tendency for the temperature to rise, the smaller the type score P1. The thinner the sheet P, the greater the tendency for the temperature to rise. In other words, the thicker the sheet P, the greater the type score P1. Furthermore, in the first conversion table T1, the smaller the moisture content of the sheet P, the greater the tendency for the temperature to rise. In the first conversion table T1, the greater the moisture content of the sheet P, the greater the moisture content score P2.

[0080] 5, in the second conversion table T2, the larger the total score TP, the larger the judgment threshold time T. The total score TP is the sum of the type score P1 and the moisture content score P2.

[0081] As shown in FIG. 3, the setting unit 52 obtains a total score TP by adding up the type score P1 and the moisture content score P2. As shown in FIG. 5, the setting unit 52 sets the judgment threshold time T by the total score TP and the second conversion table T2. Therefore, the setting unit 52 sets the judgment threshold time T longer as the thickness of the sheet P increases or the moisture content of the sheet P increases. Therefore, when the temperature is increasing, the judgment threshold time T becomes smaller, and when the temperature is increasing, the judgment threshold time T becomes larger. In other words, the judgment threshold time T can be changed depending on the susceptibility of the sheet P to deterioration due to heat. As a result, a jam of the sheet P that is easily deteriorated by heat can be determined early, and a jam of the sheet P that is not easily deteriorated by heat can be determined accurately.

[0082] The time measurement unit 53 measures the elapsed time t that the sheet P has stayed in the heating unit 30 from the difference between the time when the first detection unit 62 detects that the sheet P has been carried into the heating unit 30 and the time when the second detection unit 63 detects that the sheet P has been carried out of the heating unit 30. Therefore, it is possible to determine with high accuracy whether the sheet P has been jammed inside the heating unit 30.

[0083] As shown in FIG. 3, the control unit 5 further includes a heating control unit 55 that controls the heating unit 30.

[0084] The heating control unit 55 stops the heating unit 30 based on the determination result of the determination unit 54. Therefore, when a jam of the sheet P occurs, the heating unit 30 can be limited to a minimum. As a result, deterioration of the sheet P due to heating inside the heating unit 30 can be suppressed.

[0085] Next, a sheet jam determination process performed by the control unit 5 will be described with reference to Fig. 6. Fig. 6 is a flowchart showing an example of the process performed by the control unit 5. As shown in Fig. 6, the process performed by the control unit 5 includes steps S1 to S11. Steps S1 to S11 are performed by the processor of the control unit 5 executing a program.

[0086] 6, in step S1, the acquisition unit 51 reads various pieces of information. The process proceeds to step S2.

[0087] In step S2, the control unit 5 determines whether or not the sheet P has been carried into the heating unit 30. If the control unit 5 determines that the sheet P has not been carried into the heating unit 30 (No in step S2), the process ends. If the control unit 5 determines that the sheet P has been carried into the heating unit 30 (Yes in step S2), the process proceeds to step S3.

[0088] In step S3, the setting unit 52 sets a determination threshold time T. The process proceeds to step S4.

[0089] In step S4, the timer 53 starts counting the elapsed time t. The process proceeds to step S5.

[0090] In step S5, the time measurement unit 53 adds 1 to the elapsed time t. The process proceeds to step S6.

[0091] In step S6, the determination unit 54 determines whether the elapsed time t has exceeded the determination threshold time T. If the determination unit 54 determines that the elapsed time t has not exceeded the determination threshold time T (No in step S6), the process proceeds to step S11. If the determination unit 54 determines that the elapsed time t has exceeded the determination threshold time T (Yes in step S6), the process proceeds to step S7.

[0092] In step S7, the determination unit 54 determines whether there is a jam of the sheet P. The process proceeds to step S8.

[0093] In step S8, the heating control unit 55 stops heating by the heating unit 30. The process proceeds to step S9.

[0094] In step S9, the timer 53 ends counting the elapsed time t. The process proceeds to step S10.

[0095] In step S10, the time measurement unit 53 sets the elapsed time t to 0. The process then ends.

[0096] If the answer is No in step S6, in step S11, the control unit 5 determines whether or not the sheet P has been conveyed out of the heating unit 30. If the control unit 5 determines that the sheet P has been conveyed out of the heating unit 30 (Yes in step S11), a jam of the sheet P has not occurred, and the process proceeds to step S9. If the control unit 5 determines that the sheet P has not been conveyed out of the heating unit 30 (No in step S11), the sheet P is still staying in the heating unit 30, and the process returns to step S5. In this manner, the sheet jam determination process is executed.

[0097] <Embodiment 2> An image forming apparatus 1A according to embodiment 2 will be described with reference to Fig. 7. The image forming apparatus 1A in embodiment 2 is mainly different from embodiment 1 in that the image forming apparatus 1A is an electrophotographic type. Below, the differences between embodiment 2 and embodiment 1 will be described, and the rest of the description of embodiment 1 will be applied to embodiment 2.

[0098] FIG. 7 is a diagram showing a configuration of an image forming apparatus 1A according to the second embodiment.

[0099] The image forming unit 81 forms an image on a sheet P using toner. The image forming unit 81 has a first toner container 811, a second toner container 812, a third toner container 813, and a fourth toner container 814. In this embodiment, the first toner container 811 contains yellow toner. The second toner container 812 contains cyan toner. The third toner container 813 contains magenta toner. The fourth toner container 814 contains black toner.

[0100] When the image forming apparatus 1A is of an electrophotographic type, the image forming section 81 includes, for example, a photosensitive drum 82, a charging device 83, an exposure device 84, a developing device 85, a transfer device 86, a cleaning device (not shown), a discharge device, a fixing section 87, and a control section 88.

[0101] The photoconductor drum 82 has a photosensitive layer on its outer circumferential surface. An example of the photoconductor drum 82 is a selenium drum or an OPC (Organic Photoconductor).

[0102] The charging device 83 charges the photosensitive layer of the photosensitive drum 82 to a predetermined potential. An example of the charging device 83 is a corona discharger.

[0103] The exposure device 84 irradiates and exposes a photosensitive layer of the photosensitive drum 82 with laser light. The exposure device 84 exposes the photosensitive layer of the photosensitive drum 82 based on image data. As a result, an electrostatic latent image is formed on the photosensitive drum 82. An example of the exposure device 84 is an LED (Light Emitting Diode).

[0104] The developing device 85 contains, for example, a two-component developer containing a carrier made of a magnetic material and a toner. The developing device 85 develops the electrostatic latent image formed on the photoconductor drum 82 with the toner to form a toner image on the photoconductor drum 82. The toner images formed are a yellow toner image, a cyan toner image, a magenta toner image, and a black toner image.

[0105] The transfer device 86 transfers each toner image formed on the surface of each photoconductor drum 82 onto a sheet P. The transfer device 86 includes an intermediate transfer belt 90, a primary transfer roller 91, and a secondary transfer roller 92.

[0106] The primary transfer rollers 91 are disposed opposite each of the photoconductor drums 82 via the intermediate transfer belt 90, and are pressed against each of the photoconductor drums 82. Therefore, the toner images formed on the surfaces of the photoconductor drums 82 are transferred sequentially to the intermediate transfer belt 90. A transfer nip is formed between the secondary transfer roller 92 and the drive roller 89. When the sheet P passes through the transfer nip, the laminated toner image on the intermediate transfer belt 90 is transferred to the sheet P. The sheet P to which the laminated toner image has been transferred is transported by a transport unit 96 toward the fixing unit 87.

[0107] The cleaning device removes residual toner remaining on the photoconductor drum 82 after transfer. The charge removing device removes charge from the photoconductor drum 82.

[0108] The fixing unit 87 applies heat and pressure to the toner image developed on the sheet P, thereby fixing the toner image to the sheet P. The fixing unit 87 has, for example, a fixing roller 871, a heater (not shown), and a press roller 872.

[0109] The fixing roller 871 is a hollow cylindrical roller. The fixing roller 871 is pressed against the press roller 872. The press roller 872 and the fixing roller 871 form a nip portion. The press roller 872 is rotationally driven by a drive unit (not shown). The press roller 872 rotates the fixing roller 871.

[0110] The heater receives power from a power source (not shown) and heats the fixing roller 871. The heater is disposed close to the inner circumferential surface of the fixing roller 871. The sheet P conveyed to the fixing section passes through the nip section and is heated by the heater, so that the toner image is fixed. The fixing section 87 corresponds to, for example, a "heating section."

[0111] In the transport section 96, a detection section 93, a first detection section 94, and a second detection section 95 are disposed.

[0112] The detection unit 93 detects medium information of the sheet P. The detection unit 93 is, for example, a media sensor that detects the type and moisture content of the sheet P. The detection unit 93 is disposed at a downstream position of the secondary transfer roller 92.

[0113] The first detection unit 94 and the second detection unit 95 detect the conveyed sheet P. The first detection unit 94 is disposed between the detection unit 93 and the fixing unit 87. The second detection unit 95 is disposed at a downstream position of the fixing unit 87.

[0114] The control unit 88 determines whether the sheet P is jammed in the fixing unit 87 based on the elapsed time t and the determination threshold time T. The elapsed time t is the time that has elapsed since the sheet P was transported into the fixing unit 87. Note that, "inside the fixing unit 87" refers to an area that is affected by heat from the fixing unit 87.

[0115] The embodiments of the present 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 scope of the present invention. The drawings are mainly schematic illustrations of each component for ease of understanding, and the thickness, length, number, etc. of each component shown in the drawings are different from the actual ones due to the convenience of drawing. In addition, the materials, shapes, dimensions, etc. of each component shown in the above embodiments are merely examples, and are not particularly limited, and various modifications are possible within a scope that does not substantially deviate from the effects of the present invention.

[0116] (1) In the first embodiment, an example of the detection unit 61 in which the thickness sensor of the sheet P and the moisture content sensor of the sheet P are integrated into one unit has been described, but the present invention is not limited to this. As the detection unit, the thickness sensor of the sheet P and the moisture content sensor of the sheet P may be disposed independently. Furthermore, medium information may be detected based on the thickness, moisture content, and material of the sheet P, or the type may be detected based on other requirements.

[0117] (2) In the first embodiment, the second transport device 3 has a switchback function, but the present invention is not limited to this. The second transport device 3 may have at least a transport function capable of transporting the sheet P. [Industrial Applicability]

[0118] The present invention can be used in the field of image forming apparatuses. [Explanation of symbols]

[0119] 1: Image forming device 1A: Image forming device 25: Image forming section 30: Heating part 51: Acquisition part 52: Setting section 53: Time measurement section 54: Judgment section 55: Heating control section 61: Detection unit 62: First detection unit 63: Second detection unit 81: Image forming section 88: Control section 93: Detection unit 94: First detection unit 95: Second detection section T: Judgment threshold time t : elapsed time P: Seat

Claims

1. an image forming unit that forms an image on a recording medium; a heating section for heating the recording medium on which the image is formed; an acquisition unit that acquires medium information indicating information regarding a temperature change when the recording medium is heated; a setting unit that sets a determination threshold time based on the medium information of the recording medium; a time measurement unit that measures an elapsed time that has elapsed since the recording medium was carried into the heating unit; a determination unit that determines whether the recording medium is jammed in the heating unit based on the elapsed time and the determination threshold time; An image forming apparatus comprising:

2. The image forming apparatus according to claim 1 , wherein the medium information includes information relating to a type of the recording medium and information relating to a moisture content of the recording medium.

3. The image forming apparatus according to claim 2 , wherein the setting section sets the determination threshold time to be longer as the thickness of the recording medium increases or as the moisture content of the recording medium increases.

4. A detection unit that detects the recording medium is further provided, The image forming apparatus according to claim 2 , wherein the acquisition section generates the medium information of the recording medium based on a detection result of the detection section.

5. a first detection unit that detects when the recording medium is carried into the heating unit; a second detection unit that detects that the recording medium is conveyed out of the heating unit; Further equipped with 5. The image forming apparatus according to claim 4, wherein the time measurement unit measures the elapsed time from the difference between the time when the first detection unit detects that the recording medium is being transported into the heating unit and the time when the second detection unit detects that the recording medium is being transported out of the heating unit.

6. A heating control unit that controls the heating unit is further provided. The image forming apparatus according to claim 4 , wherein the heating control section stops heating of the heating section based on a determination result of the determination section.

Images