Image forming apparatus and program

Abstract

To suppress thermal deformation caused by the fixing of a continuous recording medium.SOLUTION: An electrophotographic image forming apparatus 100 for forming an image on a continuous recording medium M includes: an image forming section 40 for forming an image on the continuous recording medium M; a fixing section 60 having a heating roller 61 and a pressure roller 62; and discharge angle changing means 55 for changing a relative discharge angle of the continuous recording medium M from the fixing section 60. Changing the discharge angle facilitates uniform cooling of the continuous recording medium M after fixing and suppresses thermal deformation.SELECTED DRAWING: Figure 4

Description

[Technical Field]

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

[0002] In an electrophotographic image forming apparatus that forms an image on a continuous recording medium, there is a risk that the continuous recording medium may be thermally deformed due to heat generated by the fixing device. In conventional image forming devices, the pressure roller and the paper guide shaft are movable away from the heating roller of the fixing device (see, for example, Patent Document 1). This separates the continuous recording medium from the heating roller, thereby preventing thermal deformation. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-205879 Summary of the Invention [Problem to be solved by the invention]

[0004] In the conventional image forming apparatus described above, the pressure roller is separated from the heating roller, so this cannot be used as a countermeasure against thermal deformation that occurs during image formation.

[0005] An object of the present invention is to suppress thermal deformation of a continuous recording medium during image formation. [Means for solving the problem]

[0006] In order to solve the above problems, the present invention provides: An electrophotographic image forming apparatus for forming an image on a continuous recording medium, an image forming unit that forms an image on the continuous recording medium; a fixing unit having a heating roller and a pressure roller; and a discharge angle changing means for changing a relative discharge angle of the continuous recording medium from the fixing unit.

[0007] The present invention also provides a program, a computer for an image forming apparatus having an image forming unit that forms an image on the continuous recording medium, a fixing unit having a heating roller and a pressure roller, and a discharge angle changing unit that changes the discharge angle of the continuous recording medium from the fixing unit; The ejection angle changing means is controlled in accordance with the characteristics of the continuous recording medium, thereby realizing a function of changing the ejection angle. [Effects of the Invention]

[0008] According to the present invention, it is possible to suppress thermal deformation of the continuous recording medium during image formation. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a diagram illustrating an example of the overall configuration of an image forming apparatus according to an embodiment of the present invention. [Figure 2] FIG. 2 is a diagram illustrating a main part of a control system of the image forming apparatus. [Figure 3] 10 is a schematic diagram of a transport unit that transports a continuous recording medium between a paper supply unit and a winding unit, showing a state before a discharge angle is changed. FIG. [Figure 4] 10A and 10B are schematic diagrams illustrating the configuration of a transport unit that transports a continuous recording medium between a paper supply unit and a winding unit, and show a state in which the discharge angle is changed. [Figure 5] 10 is an explanatory diagram showing a stepless change in the discharge angle of the continuous recording medium relative to the fixing unit caused by the lifting and lowering operation of the second transport roller by the first lifting mechanism. FIG. [Figure 6] 10A and 10B are explanatory diagrams showing a stepwise change in the discharge angle of the continuous recording medium relative to the fixing unit caused by the lifting and lowering operation of the second transport roller by the first lifting mechanism. [Figure 7] 10A and 10B are explanatory diagrams showing the amount of wrapping of the continuous recording medium around the pressure roller and temperature changes when the second transport roller is at a reference position. [Figure 8] 8 is a cross-sectional view showing thermal deformation occurring in the continuous recording medium in the state shown in FIG. 7, taken along a cross section perpendicular to the conveying direction. [Figure 9] 10A and 10B are explanatory diagrams showing the amount of wrapping of the continuous recording medium around the pressure roller and the temperature change when the second transport roller is lowered. [Figure 10] 10 is a cross-sectional view showing thermal deformation occurring in the continuous recording medium in the state shown in FIG. 9, taken along a cross section perpendicular to the conveying direction. [Figure 11] 10 is an explanatory diagram showing a state in which a thin continuous recording medium is wrapped around a pressure roller during transport when the second transport roller is lowered; FIG. [Figure 12] 10 is an explanatory diagram showing a state in which a thick continuous recording medium is wrapped around a pressure roller during transport when the second transport roller is lowered; FIG. [Figure 13] 10 is a flowchart showing control of the discharge angle of the continuous recording medium. [Figure 14] FIG. 10 is a diagram illustrating another example of the configuration of the discharge angle changing means. [Figure 15] 10 is a schematic diagram illustrating a configuration on a conveyance path of a continuous recording medium in which nip opening control is performed when no image is formed. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0010] [Outline of the embodiment] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings, but the scope of the invention is not limited to the illustrated examples.

[0011] Fig. 1 is a diagram showing an example of the overall configuration of an image forming apparatus 100 according to the first embodiment. Fig. 2 is a diagram showing the main parts of a control system of the image forming apparatus 100. The image forming apparatus 100 is an apparatus that forms an image on a continuous recording medium M. The continuous recording medium M generally refers to long recording media on which the image forming apparatus 100 forms images. Note that, hereinafter, the terms corresponding to the continuous recording medium may be referred to as "paper" or "sheet of paper," but this does not mean that the continuous recording medium M is limited to "paper." The continuous recording medium M includes paper media such as continuous paper, roll paper, and continuous forms, as well as various sheet-like recording media on which images are formed, such as resin sheets. In this embodiment, paper, PP (polypropylene), and PET (polyethylene terephthalate) are exemplified as materials for the continuous recording medium M. However, resins other than PP and PET may also be used. In the following description, the direction in which the continuous recording medium M is transported will simply be referred to as the "transport direction."

[0012] As shown in FIG. 1, in the image forming apparatus 100, a paper feed unit 1, a main body unit 2, and a winding unit 3 are arranged in this order from the upstream side to the downstream side in the transport direction.

[0013] [Paper feed section] The paper feed unit 1 is a device that supplies continuous recording medium M to the main body unit 2. Driven by a motor (not shown), the paper feed unit 1 supplies the continuous recording medium M wound around a support shaft 101 to the main body unit 2 at a constant speed. The operation of the motor of the paper feed unit 1 is controlled by a control unit 10 provided in the main body unit 2.

[0014] [Winding section] The winding unit 3 is a device that winds up the continuous recording medium M that has been transported from the main body 2. Driven by a motor (not shown), the winding unit 3 winds up the continuous recording medium M that has been transported from the main body 2 at a constant speed around a support shaft 301. The winding operation of the winding unit 3 is controlled by a control unit 10 provided in the main body 2.

[0015] [Main body] The main body 2 forms an image on a continuous recording medium M supplied from the paper feeder 1 by an intermediate transfer method using electrophotographic process technology. The main body 2 will be described with reference to Figures 1 and 2. The main body 2 includes a control unit 10, a storage unit 20, an operation display unit 30, an image forming unit 40, a conveying unit 50, a fixing unit 60, a communication unit 70, and the like.

[0016] The control unit 10 includes a CPU (Central Processing Unit) 11, a ROM (Read Only Memory) 12, a RAM (Random Access Memory) 13, etc. The CPU 11 reads out a program corresponding to the processing content from the ROM 12 and loads it into the RAM 13. The CPU 11 works in conjunction with the loaded program to centrally control the operations of each part of the main body unit 2, the paper feed unit 1, the winding unit 3, etc. The control unit 10 is a so-called control device.

[0017] The storage unit 20 is configured, for example, by a non-volatile semiconductor memory such as a flash memory, a hard disk drive, etc. The storage unit 20 stores input document data of the image to be formed, various setting information, image data, etc. Note that these data, etc. may also be stored in the RAM 13 of the control unit 10.

[0018] The operation display unit 30 is configured by, for example, a liquid crystal display (LCD) with a touch panel. The operation display unit 30 functions as a display unit 31 and an operation unit 32. The display unit 31 displays various operation screens, image states, operation statuses of various functions, etc. in accordance with a display control signal input from the control unit 10. The operation unit 32 includes various operation keys such as a numeric keypad and a start key, and receives various input operations from the user and outputs operation signals to the control unit 10.

[0019] The image forming unit 40, for example, acquires image data from an external device (such as a personal computer) via the communication unit 70. Then, the image forming unit 40 forms an image on the continuous recording medium M based on the image data. Image forming unit 40 has a writing unit for each of the colors Y (yellow), M (magenta), C (cyan), and K (black). Each writing unit has an exposure unit 41, a photosensitive drum 42, a primary transfer roller 43, and a developing unit, a charging unit, a cleaning unit, and the like (not shown).

[0020] The photosensitive drum 42 includes a rotating conductive cylindrical body (photosensitive body). The charging unit charges the photosensitive drum 42. The exposure unit 41 has a semiconductor laser light source. The control unit 10 irradiates and exposes the charged photosensitive drum 42 with laser light based on image data, thereby forming an electrostatic latent image. The developing unit supplies toner onto the photosensitive drum 42 by a charged developing roller under the control of the control unit 10, thereby developing the electrostatic latent image. The toner images formed on the photosensitive drums 42 of the writing units of each of the four colors are transferred in layers onto an intermediate transfer belt 44 by a primary transfer roller 43. A color toner image made up of each color is formed on the intermediate transfer belt 44, which serves as a transfer body. After transfer, a cleaning unit removes any remaining toner from the photosensitive drums 42. The intermediate transfer belt 44 as a transfer body may be configured as a drum instead of a belt.

[0021] A secondary transfer roller 45 is disposed below the intermediate transfer belt 44, facing it across a nip portion. The toner images superimposed on the intermediate transfer belt 44 are secondarily transferred by the secondary transfer roller 45 to the continuous recording medium M passing through the nip portion. In this way, an image is formed (printed) on the continuous recording medium M.

[0022] The fixing unit 60 fixes the image to the continuous recording medium M by applying heat and pressure to the continuous recording medium M on which the image has been formed, under the control of the control unit 10. The fixing unit 60 includes a heating roller 61 and a pressure roller 62 as a heating unit.

[0023] The heating roller 61 incorporates a heater 611 as a heat source, and is heated to a predetermined heating temperature under the control of the control unit 10. The pressure roller 62 is pressed against the heating roller 61 by an elastic member (not shown). The pressure roller 62 does not have a built-in heater. Therefore, the surface temperature of the pressure roller 62 is maintained lower than that of the heating roller 61 during fixing. As a specific example, the surface temperature of the heating roller 61 is maintained at 200°C, and the surface temperature of the pressure roller 62 is maintained at 50°C. Note that the temperature setting of the heating roller 61 may be set to a value other than these set temperatures, as long as it is higher than that of the pressure roller 62. Furthermore, if the target temperature difference can be maintained, the pressure roller 62 may also have a built-in heater. The continuous recording medium M on which the image has been formed passes through the nip between the heating roller 61 and the pressure roller 62, whereby the image is fixed by the application of heat and pressure.

[0024] [Main body: Transport section] 3 and 4 are schematic diagrams of a transport unit 50 that transports the continuous recording medium M between the paper feed unit 1 and the winding unit 3. In FIGS. 3 and 4, the left-right direction and the vertical direction of the paper are horizontal directions. 3 and 4, the conveying path of the conveying unit 50 is drawn with an upward gradient from the paper feed unit 1 toward the winding unit 3, but the conveying path may be horizontal as in FIG.

[0025] The conveying section 50 has a plurality of rollers that convey the continuous recording medium M from the paper supply section 1 to the winding section 3, forming a conveying path. Along the transport path, an image forming unit 40 and a fixing unit 60 are arranged in this order toward the downstream side in the transport direction. The transport path passes through a nip between an intermediate transfer belt 44 and a secondary transfer roller 45 and a nip between a heating roller 61 and a pressure roller 62.

[0026] A tension roller 51 and a first transport roller 52 are arranged in this order in the transport direction between the paper feed unit 1 and the transport path of the image forming unit 40. The rotational center lines of the tension roller 51 and the first transport roller 52 are oriented in the direction perpendicular to the paper surface in Figures 3 and 4. The rotational center lines of the heating roller 61 and pressure roller 62 of the fixing unit 60 described above are also oriented in the direction perpendicular to the paper surface in Figures 3 and 4.

[0027] The tension roller 51 is positioned lower than the first transport roller 52 so as to divert the continuous recording medium M fed from the paper feed unit 1 downward. The first transport roller 52 is positioned higher than the tension roller 51 and guides the continuous recording medium M toward the image forming unit 40. The crank-shaped transport path of the tension roller 51 acts as resistance, applying tension to the continuous recording medium M that receives a transport force from the downstream side. The tension roller 51 may also divert the continuous recording medium M upward. Either or both of the tension roller 51 and the first transport roller 52 may be configured to receive power and apply a transport force to the continuous recording medium M. Alternatively, either or both of the tension roller 51 and the first transport roller 52 may be configured as a pair of rollers through which the continuous recording medium M passes.

[0028] A second transport roller 53 and a tension roller 54 are disposed in this order toward the downstream side in the transport direction between the fixing unit 60 and the winding unit 3. The rotational center lines of the second transport roller 53 and the tension roller 54 are oriented in the direction perpendicular to the paper surface of FIGS.

[0029] The tension roller 54 is positioned lower than the second transport roller 53 so as to detour the continuous recording medium M downward from the second transport roller 53. The winding unit 3 winds up the continuous recording medium M at a position higher than the tension roller 54. In the case of the tension roller 54, similar to the tension roller 51, tension can be applied to the continuous recording medium M by a crank-shaped transport path. Note that the tension roller 54 may also detour the continuous recording medium M upward.

[0030] The second transport roller 53 is a member that the continuous recording medium M first comes into contact with after passing through the fixing unit 60. The second transport roller 53 is disposed at a position closest to the fixing unit 60 among the rollers of the transport unit 50 that are downstream of the fixing unit 60 in the transport direction. The second transport roller 53 is supported by a first lifting mechanism 55 that supports the second transport roller 53 so that it can be raised and lowered vertically.

[0031] Here, the height of the second transport roller 53 in Fig. 3 is taken as the reference position. The transport path of the continuous recording medium M from the upstream side of the fixing unit 60 to the second transport roller 53 at the reference position is linear as shown in Fig. 3. The heating roller 61 and pressure roller 62 of the fixing unit 60 are arranged side by side in a direction perpendicular to the transport path. In other words, the continuous recording medium M transported along this transport path passes in contact with the heating roller 61 and pressure roller 62 almost only at the nip portions. The continuous recording medium M passes with a minimum contact area without wrapping around the outer circumferential surfaces of either the heating roller 61 or the pressure roller 62.

[0032] The first lifting mechanism 55 can lower the second transport roller 53 by any amount, with the reference position being the upper limit height. The first lifting mechanism 55 has, for example, an actuator such as a motor that can raise and lower the rotation shaft of the second transport roller 53 by any amount of movement. The actuator of the first lifting mechanism 55 is configured so that the amount of movement can be controlled by the control unit 10. The first lifting mechanism 55 may also be configured to be able to control the movement of the second transport roller 53 above the reference position.

[0033] 5 is an explanatory diagram showing a change in the discharge angle of the continuous recording medium M relative to the fixing unit 60 due to the lifting and lowering operation of the second transport roller 53 by the first lifting mechanism 55. In the following description, the "discharge angle of the continuous recording medium M relative to the fixing unit 60" may be abbreviated to simply "discharge angle." The first lifting mechanism 55 can arbitrarily change the discharge angle θ of the continuous recording medium M from the fixing unit 60 by arbitrarily raising and lowering the second transport roller 53. Furthermore, the first lifting mechanism 55 can arbitrarily increase or decrease the amount of wrapping of the continuous recording medium M around the pressure roller 62 by raising and lowering the second transport roller 53. In particular, when the second transport roller 53 descends from the reference position, the amount of wrapping of the continuous recording medium M around the pressure roller 62 increases. In other words, the second transport roller 53 and the first lifting mechanism 55 constitute a discharge angle changing means.

[0034] The discharge angle of the continuous recording medium M relative to the fixing unit 60 may be continuously adjustable without any steps as shown in Fig. 5, but is not limited to this. For example, as shown in Fig. 6, the discharge angle of the continuous recording medium M relative to the fixing unit 60 may be adjustable in steps such as 0, θA, θB, and θC. θA, θB, and θC are, for example, 10°, 20°, and 30°. However, these values ​​are merely examples and can be changed as appropriate. In this case, the amount of the continuous recording medium M wrapped around the pressure roller 62 is also changed and adjusted in stages in accordance with the discharge angle of the continuous recording medium M.

[0035] Here, the influence of thermal deformation due to changes in the amount of wrapping of the continuous recording medium M around the pressure roller 62 will be described with reference to FIGS. Fig. 7 shows the temperature change and the amount of wrapping of the continuous recording medium M around the pressure roller 62 when the second transport roller 53 is in the reference position. Fig. 8 is a cross-sectional view perpendicular to the transport direction showing the thermal deformation occurring in the continuous recording medium M in the state shown in Fig. 7. 9 shows the temperature change and the amount of wrapping of the continuous recording medium M around the pressure roller 62 when the second transport roller 53 descends from the reference position. Fig. 10 is a cross-sectional view perpendicular to the transport direction showing the thermal deformation occurring in the continuous recording medium M in the state shown in Fig. 9. In addition, the dot shading patterns in Figures 7 and 9 indicate higher temperatures as the dots become darker. Note that the shapes of the shading patterns visualizing the temperature changes in Figures 7 and 9 are conceptual and simplified for ease of understanding. The actual shapes may be more complex and irregular.

[0036] 7 and 9 show the conveyed continuous recording medium M viewed from a direction perpendicular to the medium plane. The symbol R1 in the figures indicates the heating area of ​​the continuous recording medium M relative to the pressure roller 62. This heating area R1 coincides with the width of the nip portion between the heating roller 61 and the pressure roller 62 in the conveyance direction. When the second transport roller 53 is in the reference position in Figure 7, the continuous recording medium M passes through the heating roller 61 and pressure roller 62, contacting them only in the heating region R1. In this case, after passing through the nip portion, the continuous recording medium M separates from the heating roller 61 and pressure roller 62 and is rapidly cooled by the surrounding atmosphere. Gases such as the atmosphere tend to flow, which causes a lot of disturbance, and the continuous recording medium M cooled by the atmosphere is unlikely to be cooled uniformly across its width. Note that the "width direction" is the direction parallel to the medium plane of the continuous recording medium M and perpendicular to the transport direction. If the continuous recording medium M is suddenly cooled unevenly in the width direction, uneven thermal shrinkage occurs, and as shown in FIG. 8, the amount of thermal deformation (unevenness) can become large.

[0037] 9, when the second transport roller 53 moves down from the reference position, the amount of wrapping of the continuous recording medium M around the pressure roller 62 increases. The symbol R2 indicates the contact area of ​​the continuous recording medium M with the pressure roller 62 downstream of the nip portion. As described above, the pressure roller 62 is adjusted to have a lower temperature than the heating roller 61. Therefore, the continuous recording medium M that has passed through the nip portion is cooled by heat conduction due to contact with the pressure roller 62 in the contact region R2. In this case, unlike when the continuous recording medium M is cooled in the atmosphere, the temperature of the continuous recording medium M drops relatively uniformly in the width direction. Furthermore, the continuous recording medium M is separated after being cooled by the pressure roller 62. Therefore, even when the continuous recording medium M is subsequently cooled in the atmosphere, the cooling does not occur suddenly, and uneven cooling is mitigated. Therefore, the continuous recording medium M is prevented from undergoing non-uniform thermal shrinkage in the width direction, and as shown in FIG. 10, it is possible to reduce the amount of thermal deformation (unevenness).

[0038] [Control of continuous recording medium ejection angle by control unit] The control of the discharge angle of the continuous recording medium M relative to the fixing unit 60 by the control unit 10 will be described. The CPU 11 of the control unit 10 controls the first lifting mechanism 55 as a discharge angle changing means in accordance with the characteristics of the continuous recording medium M. The characteristic of the continuous recording medium M is the material of the continuous recording medium M. The material of the continuous recording medium M can be input by the user through the operation unit 32. The material of the continuous recording medium M can be input by selecting "PP," "PET," "paper," etc. through the operation unit 32. Note that these are just examples of the material of the continuous recording medium M, and the material is not limited to the above. The materials of the continuous recording medium M tend to be most susceptible to thermal deformation in the following order: PP > PET > paper.

[0039] Another characteristic of the continuous recording medium M is the thickness of the continuous recording medium M. The thickness of the continuous recording medium M is inputted from the operation unit 32 as a numerical value. The influence of the thickness of the continuous recording medium M on the discharge angle of the continuous recording medium M relative to the fixing unit 60 will be described.

[0040] FIG. 11 is an explanatory diagram showing a state in which the thin continuous recording medium M is wound around the pressure roller 62 during conveyance when the second conveyance roller 53 is lowered. In this case, the continuous recording medium M is subjected to tension on both the upstream and downstream sides as it is transported, and the combined force of these forces presses it against the pressure roller 62. Because the continuous recording medium M is in close contact with the entire area where it is faithfully wrapped around the outer circumferential surface of the pressure roller 62, heat is efficiently transferred to the pressure roller 62, and it is cooled.

[0041] FIG. 12 is an explanatory diagram showing a state in which the thick continuous recording medium M is wound around the pressure roller 62 during conveyance when the second conveyance roller 53 is lowered. In this case, the continuous recording medium M is also subjected to tension on both the upstream and downstream sides as it is transported. However, thicker continuous recording media M have higher rigidity. Therefore, the continuous recording medium M that has passed through the nip portion of the fixing unit 60 tends to move straight due to its rigidity, and the resultant force toward the pressure roller 62 is reduced. As a result, the continuous recording medium M that has passed through the nip portion is transported by repeatedly moving straight and then curving along the pressure roller 62 due to the tension. This causes the continuous recording medium M to alternate between contacting and not contacting the downstream side of the nip portion of the pressure roller 62, which can result in uneven thermal shrinkage. Therefore, when the thickness of the continuous recording medium M increases, it is preferable not to make the amount of change in the discharge angle too large.

[0042] Before image formation, the CPU 11 receives input of the thickness and material of the continuous recording medium M from the user and registers it in the storage unit 20. Then, the CPU 11 determines the discharge angle of the continuous recording medium M from the fixing unit 60 during image formation according to the input content, and controls the first lifting mechanism 55. The thickness and material of the continuous recording medium M do not necessarily have to be input by the user. For example, a sensor that detects or identifies the thickness or material of the continuous recording medium M may be provided on the conveyance path, and the thickness and material may be obtained from the sensor output.

[0043] The control unit 10 executes the discharge angle control of the continuous recording medium shown in the flowchart of Fig. 13, taking into consideration the above-mentioned characteristics of the continuous recording medium M. This discharge angle control is executed by the CPU 11 of the control unit 10 in cooperation with a program stored in the ROM 12.

[0044] As a prerequisite for controlling the discharge angle, the CPU 11 refers to the registered contents of the thickness and material of the continuous recording medium M in the storage unit 20 that have been input in advance before image formation. Then, when an execution command for image formation is input, the CPU 11 starts controlling the discharge angle of the continuous recording medium.

[0045] Before starting the conveyance of the continuous recording medium M, the CPU 11 determines whether the material setting of the continuous recording medium M is PP (S1). If the material is PP, the CPU 11 determines whether the thickness of the continuous recording medium M is set to 80 μm or less (S3). If the thickness of the continuous recording medium M is 80 μm or less, the CPU 11 controls the first lifting mechanism 55 to adjust the discharge angle of the continuous recording medium M to 30° (S5). Then, the CPU 11 starts conveying the continuous recording medium M by the conveying unit 50 and executes image formation by the image forming unit 40 (S7). The image formed on the continuous recording medium M is discharged at a discharge angle set in the fixing unit 60 and conveyed to the winding unit 3 in a state where thermal deformation is suppressed. Then, when the scheduled image formation is completed, the CPU 11 controls the first lifting mechanism 55 to return the discharge angle of the continuous recording medium M to 0° (S9). Then, the CPU 11 ends the control of the discharge angle of the continuous recording medium.

[0046] On the other hand, if the thickness of the continuous recording medium M is not 80 μm or less in S3, the CPU 11 determines whether the thickness setting is 120 μm or less (S11). If the thickness of the continuous recording medium M is 120 μm or less, the CPU 11 controls the first lifting mechanism 55 to adjust the discharge angle of the continuous recording medium M to 20° (S13). Thereafter, the CPU 11 goes through the processes of S7 and S9 described above and ends the control of the discharge angle of the continuous recording medium.

[0047] On the other hand, if the thickness of the continuous recording medium M is not 120 μm or less in S11, the CPU 11 determines whether the thickness setting is 160 μm or less (S15). If the thickness of the continuous recording medium M is 160 μm or less, the CPU 11 controls the first lifting mechanism 55 to adjust the discharge angle of the continuous recording medium M to 10° (S17). Thereafter, the CPU 11 goes through the processes of S7 and S9 described above and ends the control of the discharge angle of the continuous recording medium.

[0048] On the other hand, if the thickness of the continuous recording medium M is not 160 μm or less in S15, the CPU 11 maintains the discharge angle at 0°. Then, after the processes of S7 and S9 described above, the CPU 11 ends the discharge angle control of the continuous recording medium. In this case, the process of S9 may be skipped.

[0049] On the other hand, if it is determined in S1 that the material is not PP, the CPU 11 determines whether the material setting of the continuous recording medium M is PET (S19). If the material is PET, the CPU 11 determines whether the thickness of the continuous recording medium M is set to 80 μm or less (S21). If the thickness of the continuous recording medium M is 80 μm or less, the CPU 11 controls the first lifting mechanism 55 to adjust the discharge angle of the continuous recording medium M to 20° (S13). The subsequent processing is the same as S7 and S9 described above.

[0050] On the other hand, if the thickness of the continuous recording medium M is not 80 μm or less in S21, the CPU 11 determines whether the thickness setting is 120 μm or less (S23). If the thickness of the continuous recording medium M is 120 μm or less, the CPU 11 controls the first lifting mechanism 55 to adjust the discharge angle of the continuous recording medium M to 10° (S17). The subsequent processing is the same as S7 and S9 described above.

[0051] On the other hand, if it is determined in S23 that the thickness of the continuous recording medium M is not 120 μm or less, the CPU 11 maintains the discharge angle at 0°. The subsequent processing is the same as in S7 and S9 described above.

[0052] On the other hand, if it is determined in S19 that the material is not PET, the CPU 11 determines whether the material setting of the continuous recording medium M is paper (S25). If the material is paper, the CPU 11 determines whether the thickness of the continuous recording medium M is set to 80 μm or less (S27). If the thickness of the continuous recording medium M is 80 μm or less, the CPU 11 controls the first lifting mechanism 55 to adjust the discharge angle of the continuous recording medium M to 10° (S17). The subsequent processing is the same as S7 and S9 described above.

[0053] On the other hand, if it is determined in S27 that the thickness of the continuous recording medium M is not 80 μm or less, the CPU 11 maintains the discharge angle at 0°. The subsequent processing is the same as in S7 and S9 described above.

[0054] On the other hand, if it is determined in S25 that the material is not paper, the CPU 11 determines that the material of the continuous recording medium M cannot be identified and ends the process. In this case, the CPU 11 may display on the display unit 31 that the material of the continuous recording medium M cannot be identified. If the material of the continuous recording medium M cannot be identified, the CPU 11 may carry out conveyance of the continuous recording medium M and image formation while keeping the discharge angle at 0°.

[0055] The numerical values ​​of the discharge angle corresponding to the material and thickness of the continuous recording medium M are merely examples and are not limiting. The thickness of the continuous recording medium M may be selected from a number of stepwise values.

[0056] In the above-described control of the discharge angle of the continuous recording medium, as shown in FIG. 6, an example has been given in which the discharge angle of the continuous recording medium M is changed and adjusted in stages. However, in controlling the discharge angle of the continuous recording medium, the discharge angle of the continuous recording medium M may be continuously changed and adjusted without any steps, as shown in Fig. 5. In this case, the control unit 10 prepares in the memory unit 20 a mathematical formula θ=f(t) that indicates a function of the discharge angle θ and the thickness t of the continuous recording medium M. The CPU 11 then calculates the discharge angle θ from the set thickness t of the continuous recording medium M using the mathematical formula θ=f(t), and controls the first lifting mechanism 55. In this case, the control unit 10 should prepare the formula θ=f(t) for each material of the continuous recording medium M individually. Furthermore, instead of the formula, table data storing the correspondence between the discharge angle θ and the thickness t of the continuous recording medium M may be prepared for each material of the continuous recording medium M.

[0057] Furthermore, the discharge angle control described above can be changed depending on the type of material of the continuous recording medium M. In this case, data and formulas for specifying the discharge angle for each thickness of the continuous recording medium M according to the type of material may be prepared.

[0058] [Technical Effects of the Embodiments of the Invention] The image forming apparatus 100 has a second transport roller 53 and a first lifting mechanism 55 as a discharge angle changing unit for changing the discharge angle of the fixing unit 60 for the continuous recording medium M. This allows the image forming apparatus 100 to stabilize the cooling state of the continuous recording medium M that has passed through the nip portion of the fixing unit 60, thereby suppressing thermal deformation. Furthermore, since the method does not involve separating the nip portion of the fixing unit 60 in order to suppress thermal deformation of the continuous recording medium M, it is possible to suppress thermal deformation of the continuous recording medium M during image formation.

[0059] Furthermore, the image forming apparatus 100 has a control unit 10 that controls the first lifting mechanism 55 in accordance with the characteristics of the continuous recording medium M to change the discharge angle. Therefore, the image forming apparatus 100 can adjust the discharge angle to match the characteristics of the continuous recording medium M, and can more effectively suppress thermal deformation of the continuous recording medium M.

[0060] In the image forming apparatus 100, the discharge angle changing means changes the discharge angle, thereby changing the amount of the continuous recording medium M wrapped around the pressure roller 62. Therefore, the image forming apparatus 100 can cool the continuous recording medium M using the pressure roller 62, and can suppress thermal deformation due to stable cooling. In particular, by setting the pressure roller 62 at a lower temperature than the heating roller 61 during image formation, it becomes possible to stabilize the cooling of the continuous recording medium M and suppress thermal deformation.

[0061] The discharge angle changing means also has a second transport roller 53 that changes its position downstream of the fixing unit 60 in the transport direction to change the discharge angle. This makes it possible to change the discharge angle of the continuous recording medium M with a simple configuration and maintain a smooth conveyance state.

[0062] The CPU 11 of the control unit 10 changes the discharge angle of the continuous recording medium M based on the thickness of the continuous recording medium M. This allows the discharge angle to be adjusted in consideration of the effect of rigidity according to the thickness of the continuous recording medium M, and thermal deformation of the continuous recording medium M can be more effectively suppressed.

[0063] The CPU 11 of the control unit 10 changes the discharge angle of the continuous recording medium M based on the material of the continuous recording medium M. This makes it possible to adjust the discharge angle of the continuous recording medium M appropriately depending on the material of the continuous recording medium M, and to more effectively suppress thermal deformation of the continuous recording medium M.

[0064] The CPU 11 of the control unit 10 controls the discharge angle to 20° when the material type of the continuous recording medium M is PP and the thickness is 120 μm or less. This allows the image forming apparatus 100 to optimize the discharge angle for the specific characteristics of the continuous recording medium M, and more effectively suppress thermal deformation of the continuous recording medium M.

[0065] The CPU 11 of the control unit 10 controls the first lifting mechanism 55 to change the discharge angle in stages. This allows the image forming apparatus 100 to optimize the discharge angle in accordance with the characteristics of the continuous recording medium M and to simplify operation control. Furthermore, the CPU 11 of the control unit 10 controls the first lifting mechanism 55 to continuously change the discharge angle. This allows the image forming apparatus 100 to precisely optimize the discharge angle in accordance with the characteristics of the continuous recording medium M.

[0066] [Other examples of discharge angle change methods] 14 is a diagram showing the configuration of another example of the discharge angle change means. The discharge angle change means described above changes the discharge angle by moving the second transport roller 53 up and down, but it is also possible to use something other than a transport roller. For example, the second transport roller 53 is fixed at a reference position, and a discharge angle change member that moves up and down is used on the fixing unit 60 side of the second transport roller 53. The discharge angle change member may be a roller, or as shown in the figure, a sliding body 56 that slides in contact with the continuous recording medium M without rotating. The lifting mechanism that moves up and down the discharge angle change member preferably includes an actuator that can arbitrarily control the amount of lifting movement, and can be controlled by the control unit 10. When a sliding body is used, the lifting mechanism does not need to lift and lower the sliding body while rotatably supporting it, so that the support structure can be simplified.

[0067] [Example of nip opening control during non-image formation] FIG. 15 is a schematic diagram showing the configuration on the transport path of the continuous recording medium M in which nip opening control is performed when no image is being formed. The image forming apparatus 100 includes second and third lifting mechanisms 46 and 63 that open the nip portions of the image forming unit 40 and the fixing unit 60, respectively. The second lifting mechanism 46 has an actuator that can lower the secondary transfer roller 45 by a predetermined amount. The third lifting mechanism 63 has an actuator that can lower the pressure roller 62 by a predetermined amount. The actuators of the second and third lifting mechanisms 46, 63 are configured so that the lowering operation and the returning operation can be controlled by the control unit 10.

[0068] During non-image formation, the control unit 10 controls the actuators to lower the secondary transfer roller 45 and the pressure roller 62, separating and opening the nips. Furthermore, at the same timing, the control unit 10 controls the first lifting mechanism 55 to lower the second transport roller 53 by a predetermined amount.

[0069] The non-image forming period refers to a period other than the period from image formation to fixation by the image forming unit 40 and the fixing unit 60. This may also include the period when the main power supply of the image forming apparatus 100 is turned off. Note that the non-image forming period also includes the period in which the continuous recording medium M is transported. An example of a period in which image formation is not performed and only the continuous recording medium M is transported is when the position of the roller around which the continuous recording medium M is wound is adjusted. This also includes a case in which the transport position of the continuous recording medium M is adjusted. The nip portions are opened and the second conveying roller 53 is lowered at a timing that allows the nip portions to be in an open state during part or all of the above period.

[0070] The amount of downward movement of the continuous recording medium M by the second transport roller 53 satisfies the following two conditions simultaneously. As shown in FIG. 15, this is the downward movement amount by which the continuous recording medium M is not in contact with the intermediate transfer belt 44 and the secondary transfer roller 45. 15, the downward movement amount is the amount by which the continuous recording medium M is not in contact with the heating roller 61 and the pressure roller 62.

[0071] When each nip portion is opened, the paper feed portion 1 and the winding portion 3 may be controlled to apply tension to the continuous recording medium M so that the continuous recording medium M does not slacken. Further, instead of the second transport roller 53, another discharge angle changing member such as a slider 56 may be used to guide the continuous recording medium M when each nip portion is opened. It is preferable that no other rollers be provided between the roller that is closest to the intermediate transfer belt 44 on the upstream side in the transport direction and the discharge angle change member.

[0072] With the above configuration, when no image is being formed, the continuous recording medium M can be maintained in a non-contact state with the heating roller 61 and the pressure roller 62. This makes it possible to prevent unnecessary heating of the continuous recording medium M and damage to either of the rollers 61, 62 due to contact. Furthermore, with the above configuration, when no image is being formed, the continuous recording medium M can be maintained in a non-contact state with the intermediate transfer belt 44 and the secondary transfer roller 45. This makes it possible to prevent scratches on the intermediate transfer belt 44 or the secondary transfer roller 45 due to contact with the continuous recording medium M. In some cases, the rollers 45, 61, and 62 are not directly powered but are driven to rotate by the other roller. In such cases, when the continuous recording medium M is transported, the rollers that do not rotate themselves may be damaged by contact with the continuous recording medium M. However, even in these cases, it is possible to effectively prevent the rollers 45, 61, and 62 from being damaged.

[0073] [others] The above describes various embodiments of the present invention. However, the present invention is not limited to the above embodiments. For example, in the embodiments, a component integrally formed from a single member may be replaced with a component divided into multiple members that are connected or fixed to each other. Furthermore, a component formed by connecting multiple members may be replaced with a component integrally formed from a single member. In addition, the details shown in the embodiments may be modified as appropriate without departing from the spirit of the invention.

[0074] In the image forming apparatus 100 described above, the control unit 10 controls the first lifting mechanism 55 to adjust the discharge angle of the continuous recording medium M, but the present invention is not limited to this. For example, the height of the second transport roller 53 may be adjusted by the user depending on the material and thickness of the continuous recording medium M. In this case, an input unit such as a lever or dial that mechanically raises or lowers the height of the second transport roller 53 may be provided, and the input unit may be manually operated.

[0075] In the above embodiment, the fixing unit 60 has a configuration in which the heating roller 61 and the pressure roller 62 form a nip portion, but the present invention is not limited to this. The fixing unit may be configured to perform fixing at a nip between the fixing belt heated by the heating unit and the pressure roller 62 .

[0076] Furthermore, although the first lifting mechanism 55 moves the second transport roller 53 downward from the reference position, the adjustment of the discharge angle is not limited to this configuration. For example, the second transport roller 53 is not limited to a downward movement, as long as it moves from the reference position toward the pressure roller 62. If the heating roller 61 and the pressure roller 62 are arranged upside down, the second transport roller 53 is moved upward from the reference position.

[0077] Furthermore, the fixing unit 60 has been exemplified as having a configuration in which the line segment connecting the centers of the heating roller 61 and the pressure roller 62 intersects the transport direction at right angles, but is not limited to this. For example, the fixing unit 60 may be arranged such that the line segment connecting the centers of the heating roller 61 and the pressure roller 62 intersects the transport direction at an angle. In this case, the reference position of the second transport roller 53 is also set to an extension of the transport direction. However, the reference position is not limited to this. The reference position may also be set to an upper or lower side of the extension of the transport direction. In other words, the reference position may be set to a state where the continuous recording medium M is wrapped around the heating roller 61 and the pressure roller 62 within a certain range.

[0078] In the above embodiment, the discharge angle changer is exemplified by the second conveying roller 53 and the first lifting mechanism 55. However, the discharge angle changer is not limited to a device that moves the downstream pass point of the continuous recording medium M up and down in the conveyance direction. The discharge angle changer may be any device that can change the discharge angle of the continuous recording medium M relative to the fixing unit 60. For example, the discharge angle changer may be a mechanism that raises or lowers the fixing unit 60 relative to the conveyance path of the continuous recording medium M. In this case, it is preferable that the amount of lift or elevation can be arbitrarily controlled by the control unit 10. Alternatively, the discharge angle changer may be a mechanism that rotates the fixing unit 60 around an axis parallel to the central axis of each roller, centered on the nip portion or its periphery. In this case, it is also preferable that the amount of rotation can be arbitrarily controlled by the control unit 10. In these configurations, the amount of wrapping of the continuous recording medium M also changes. Therefore, these configurations can cool the continuous recording medium M using the pressure roller 62, thereby suppressing thermal deformation through stable cooling. [Explanation of symbols]

[0079] 1 Paper feed section 2 Main body 3 Winding section 10 Control unit (control device) 11 CPU 12 ROM 13 RAM 20 Memory section 30 Operation display section 31 Display section 32 Operation section 40 Image forming unit 41 Exposure section 42 Photosensitive drum 43 Primary transfer roller 44 Intermediate transfer belt 45 Secondary transfer roller 46 Second lifting mechanism 50 Conveying section 51 Tension roller 52 First conveyor roller 53 Second conveying roller (discharge angle changing means, discharge angle changing member) 54 Tension roller 55 First lifting mechanism (discharge angle changing means) 56 Slider (discharge angle change member) 60 Fixing unit 61 Heating roller (heating part) 62 Pressure roller 63 Third lifting mechanism 70 Communications Department 100 Image forming device

Claims

1. An electrophotographic image forming apparatus for forming an image on a continuous recording medium, an image forming unit that forms an image on the continuous recording medium; a fixing unit having a heating unit and a pressure roller; a discharge angle changing unit for changing a relative discharge angle of the continuous recording medium from the fixing unit; An image forming apparatus having the same.

2. a control device that controls the discharge angle changing means to change the discharge angle in accordance with the characteristics of the continuous recording medium; The image forming apparatus according to claim 1 .

3. The discharge angle change unit changes the amount of the continuous recording medium wrapped around the pressure roller by changing the discharge angle. The image forming apparatus according to claim 1 .

4. The pressure roller is kept at a temperature lower than that of the heating unit during image formation. The image forming apparatus according to claim 1 .

5. The discharge angle changing unit has a roller that changes its position downstream of the fixing unit in the conveying direction to change the discharge angle. The image forming apparatus according to claim 1 .

6. The discharge angle changing means has a discharge angle changing member that abuts against the continuous recording medium downstream of the fixing unit in the conveyance direction to change the discharge angle. The image forming apparatus according to claim 1 .

7. The control device controls the discharge angle changing means based on the thickness of the continuous recording medium to change the discharge angle from the fixing unit. The image forming apparatus according to claim 2 .

8. The control device controls the discharge angle changing means based on the material of the continuous recording medium to change the discharge angle from the fixing unit. The image forming apparatus according to claim 2 .

9. The control device controls the discharge angle changing means so that the discharge angle from the fixing unit is 20° or more when the material type of the continuous recording medium is polypropylene and the thickness of the continuous recording medium is 120 μm or less. The image forming apparatus according to claim 2 .

10. The control device controls the discharge angle changing means to change the discharge angle stepwise or continuously. The image forming apparatus according to claim 2 .

11. the fixing unit is capable of separating a nip portion between the heating unit and the pressure roller, The control device separates a nip portion between the heating unit and the pressure roller during non-image formation, and controls the discharge angle change means so that the continuous recording medium is not in contact with either the heating unit or the pressure roller. The image forming apparatus according to claim 2 .

12. the image forming unit is capable of separating a nip portion between a transfer body that transfers an image onto the continuous recording medium and a secondary transfer roller, The control device separates the nip portion between the transfer body and the secondary transfer roller during non-image formation, and controls the discharge angle change means so that the continuous recording medium is not in contact with either the transfer body or the secondary transfer roller. The image forming apparatus according to claim 2 .

13. A computer of an image forming apparatus having an image forming unit that forms an image on a continuous recording medium, a fixing unit that has a heating unit and a pressure roller, and a discharge angle changing unit that changes the discharge angle of the continuous recording medium from the fixing unit, a program for realizing a function of changing the discharge angle by controlling the discharge angle changing means in accordance with the characteristics of the continuous recording medium;

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