Drying device

Abstract

The invention provides a drying device. The drying device is provided with a conveying device, a heating device, a conveying roller pair, a driving roller rotation detection part, a driven roller rotation detection part and a control part. The transport device transports a medium on which an image is formed by ink in a predetermined transport direction. And the heating device is used for drying the ink of the medium conveyed by the conveying device in a high-temperature environment. The conveying roller pair is disposed downstream of the heating device in the conveying direction, includes a driving roller that is driven to rotate and a driven roller that rotates following the driving roller, and conveys the medium that has passed through the heating device. The drive roller rotation detection unit detects rotation of the drive roller. The driven roller rotation detection unit detects rotation of the driven roller. The control unit stops the heating device when the rotation of the drive roller is detected by the drive roller rotation detection unit and the rotation period of the driven roller obtained from the detection result of the driven roller rotation detection unit is longer than a certain period. Therefore, poor conveying of the medium can be rapidly detected.

Description

Technical Field

[0001] The present invention relates to a drying device that dries a medium having an image formed thereon by ink under a high temperature environment while conveying the medium. Background Art

[0002] An image forming system including an inkjet image forming apparatus has a drying device that dries an image (ink) formed on a medium. In such a drying device, a reflective or transmissive optical sensor is often used to detect poor conveyance of the medium (conveying failure). In the drying device, a reflective optical sensor is sometimes arranged on the upstream side of a drying chamber, and a transmissive optical sensor is arranged inside the drying chamber. The feeding (input) of a sheet (medium) into the drying chamber is detected by the optical sensor on the upstream side, and the feeding (output) of a sheet from the drying chamber is detected by the optical sensor on the downstream side.

[0003] However, the above drying device has the following problem: when the leading end of the long medium is poorly conveyed after being discharged from the drying chamber, causing the medium to remain in the drying chamber, the poor conveyance of the medium cannot be detected quickly. Summary of the invention

[0004] Therefore, in view of the above-mentioned problems, an object of the present invention is to provide a drying device capable of quickly detecting a medium conveyance failure.

[0005] The drying device of the present invention comprises a conveying device, a heating device, a conveying roller pair, an active roller rotation detection unit, a driven roller rotation detection unit and a control unit. The conveying device conveys a medium having an image formed thereon by ink along a prescribed conveying direction. The heating device dries the ink of the medium conveyed by the conveying device in a high temperature environment. The conveying roller pair is arranged at a position downstream of the conveying direction relative to the heating device, and comprises an active roller (drive roller) that is driven to rotate and a driven roller (driven roller) that rotates following the active roller (rotates driven by the active roller), and is used to convey the medium passing through the heating device. The active roller rotation detection unit is used to detect the rotation of the active roller. The driven roller rotation detection unit is used to detect the rotation of the driven roller. When the rotation of the active roller is detected by the active roller rotation detection unit, and the rotation period of the driven roller obtained according to the detection result of the driven roller rotation detection unit is longer than a certain period, the control unit stops the heating device. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 It is a front view schematically showing a drying device according to one embodiment of the present invention.

[0007] Figure 2A This is a diagram showing a transport roller pair and a rotation detection sensor (when an on signal is output) in a drying device according to an embodiment of the present invention.

[0008] Figure 2B This is a diagram showing a transport roller pair and a rotation detection sensor (when an OFF signal is output) in a drying device according to an embodiment of the present invention.

[0009] Figure 2C This is a diagram showing an example of an output waveform of a rotation detection sensor in a drying device according to an embodiment of the present invention.

[0010] Figure 3A It is a diagram for explaining a transport roller pair and a rotation detection sensor (when an OFF signal is output) when medium transport is stopped in a drying device according to an embodiment of the present invention.

[0011] Figure 3B This is a diagram showing an example of an output waveform of a rotation detection sensor when medium conveyance is stopped in the drying device according to the embodiment of the present invention.

[0012] Figure 4A It is a diagram for explaining a transport roller pair and a rotation detection sensor (when an on signal is output) when a medium transport speed is reduced in a drying device according to an embodiment of the present invention.

[0013] Figure 4B It is a diagram for explaining a transport roller pair and a rotation detection sensor (when an OFF signal is output) when a medium transport speed is reduced in a drying device according to an embodiment of the present invention.

[0014] Figure 4C This is a diagram showing an example of an output waveform of a rotation detection sensor when a medium conveyance speed is reduced in a drying device according to an embodiment of the present invention.

[0015] Figure 5A It is a diagram for explaining a transport roller pair and a rotation detection sensor (when an on signal is output) in a modified example of the drying device according to the embodiment of the present invention.

[0016] Figure 5B It is a diagram for explaining a transport roller pair and a rotation detection sensor (when an OFF signal is output) in a modified example of the drying device according to the embodiment of the present invention.

[0017] Figure 5C This is a diagram showing an example of an output waveform of a rotation detection sensor in a modified example of the drying device according to the embodiment of the present invention. DETAILED DESCRIPTION

[0018] Below, while referring to the attached Figure 1 A drying device according to an embodiment of the present invention will be described.

[0019] First, refer to Figure 1 The overall structure of the drying device 1 will be described. Figure 1 1 is a front view showing the interior of the drying device 1. The drying device 1 includes a conveying device 3, a heating device 5, and a conveying roller pair 7. The conveying device 3 extends in a conveying direction ( Figure 1 The heating device 5 dries the ink of the medium transported by the transport device 3 in a high temperature environment; and the transport roller pair 7 transports the medium through the heating device 5.

[0020] First, the conveying device 3 will be described. The conveying device 3 includes a conveying belt 11 for conveying a medium, a conveying plate 13 for supporting the conveying belt 11 , and a suction device 15 for sucking the medium onto the conveying belt 11 .

[0021] The conveyor belt 11 is an endless belt having a plurality of through holes formed on the entire surface thereof and penetrating in the thickness direction. The conveyor belt 11 is wound around a driving roller 17 and a driven roller 19. The driving roller 17 is driven to rotate by a motor (not shown), thereby the conveyor belt 11 is moved along the conveyor belt 11. Figure 1 The outer surface of the conveyor belt 11 along the upper track is the conveying surface of the conveying medium (cut sheets, long sheets, etc.).

[0022] The conveyor plate 13 contacts the inner peripheral surface (the surface on the back side of the conveyor surface) of the conveyor belt 11 running along the upper track, and supports the conveyor belt 11. When the conveyor belt 11 runs, the inner peripheral surface of the conveyor belt 11 slides along the upper surface of the conveyor plate 13. A plurality of through holes penetrating in the thickness direction are formed on the entire surface of the conveyor plate 13.

[0023] The suction device 15 is disposed in the hollow portion of the conveyor belt 11. By driving the suction device 15, air is sucked into the through holes of the conveyor belt 11 and the through holes of the conveyor plate 13, whereby the medium is sucked onto the conveying surface of the conveyor belt 11.

[0024] Next, the heating device 5 is described. The heating device 5 is arranged above the conveying device 3 and has a plurality of air supply fans and a heating unit (both are omitted in the figure). The air supply fan sucks in air to generate an airflow flowing downward. The heating unit heats the generated airflow. The heating device 5 is electrically connected to the control unit 51.

[0025] Next, refer to Figure 1 , Figure 2A , Figure 2B , Figure 2CThe transport roller pair 7 will be described. Figure 2A and Figure 2B FIG. 4 is a diagram showing a conveying roller pair 7 and a rotation detection sensor 41. Figure 2C 1 is a diagram showing an example of an output waveform of the rotation detection sensor 41 .

[0026] like Figure 1 As shown, the conveying roller pair 7 is arranged downstream of the heating device 5 in the conveying direction of the medium. The conveying roller pair 7 includes a driving roller 21 and a driven roller 23. The driving roller 21 is connected to a motor 25 and is driven to rotate by the motor 25. The motor 25 is electrically connected to the control unit 51.

[0027] The driven roller 23 rotates by following the rotation of the driving roller 21 or by following the medium conveyed by the rotation of the driving roller 21. Figure 2A and Figure 2B As shown, the end portion 31 of the rotation axis of the driven roller 23 is formed in a D-shaped cut shape. That is, the end portion 31 has a flat surface 31a parallel to the rotation axis and a curved surface 31b along the circumferential direction of the rotation axis.

[0028] The rotation of the driven roller 23 is detected by the rotation detection sensor 41. The rotation detection sensor 41 is a light sensor having an emitting portion for emitting light and a light receiving portion for receiving light. The rotation detection sensor 41 is arranged below the end portion 31 of the rotating shaft of the driven roller 23 so that the light emitted from the emitting portion is incident on the end portion 31 of the rotating shaft of the driven roller 23. The rotation detection sensor 41 and the control unit 51 (see Figure 1 ) is electrically connected and sends an on signal or an off signal to the control unit 51 according to the detection result.

[0029] That is, Figure 2A As shown in FIG. 1 , when the light emitted from the emission portion is incident on the flat surface 31a approximately vertically, the light is reflected approximately vertically by the flat surface 31a and received by the light receiving portion. Then, the rotation detection sensor 41 outputs an ON signal. On the other hand, Figure 2B As shown in FIG. 1 , when the light emitted from the emission portion does not enter the flat surface 31a or the curved surface 31b substantially perpendicularly, the light is reflected in a direction different from the light receiving portion and is not received by the light receiving portion, so the rotation detection sensor 41 outputs an OFF signal. In addition, the light receiving portion of the rotation detection sensor 41 can receive light reflected by the flat surface 31a at a reflection angle within a predetermined range in addition to receiving light perpendicularly reflected by the flat surface 31a.

[0030] As a result, each time the driven roller 23 rotates one circle, the output waveform of the rotation detection sensor 41 shows "1" indicating an on signal and "0" indicating an off signal. Figure 2C As shown, "1" and "0" appear in a certain period P.

[0031] In addition, if Figure 1 As shown in FIG. 1 , a medium detection sensor 43 is disposed at a position downstream of the conveying roller pair 7 in the conveying direction. The medium detection sensor 43 is a light sensor having an emitting portion and a light receiving portion, wherein the emitting portion emits light and the light receiving portion receives light emitted from the emitting portion and reflected by the medium conveyed by the conveying roller pair 7. The medium detection sensor 43 is electrically connected to the control unit 51, and sends an on signal or an off signal to the control unit 51 according to the detection result.

[0032] Next, refer to Figure 1 The control unit 51 will be described. The control unit 51 controls the heating device 5 (air blowing fan, heating means), and drives the heating device 5 or stops driving the heating device 5.

[0033] The control unit 51 drives the motor 25 for rotating the active roller 21 of the conveying roller pair 7 or stops the drive. In addition, an on signal or an off signal is input to the control unit 51 from the rotation detection sensor 41. The control unit 51 calculates the rotation period of the driven roller 19 based on the input signal. In addition, the control unit 51 pre-stores a reference rotation period of the driven roller 19 when the medium is normally conveyed by the conveying roller pair 7. The reference rotation period is determined based on the time when a malfunction (failure) occurs in the medium due to the heating device 5. In addition, an on signal or an off signal is input to the control unit 51 from the medium detection sensor 43.

[0034] Reference Figure 1 , Figure 3A , Figure 3B , Figure 4A , Figure 4B , Figure 4C The drying operation of the drying device 1 having the above-described structure will be described. Figure 3A FIG. 4 is a diagram showing the transport roller pair 7 and the rotation detection sensor 41 when the medium transport is stopped. Figure 3B This is a diagram showing an example of an output waveform of the rotation detection sensor 41 when the medium conveyance stops. Figure 4A and Figure 4B FIG. 4 is a diagram showing the transport roller pair 7 and the rotation detection sensor 41 when the medium transport speed is reduced. Figure 4C This is a diagram showing an example of an output waveform of the rotation detection sensor 41 when the medium conveyance speed decreases.

[0035] In the conveying device 3, the driving roller 17 is driven to rotate to make the conveying belt 11 travel. After that, the medium on which the image is formed by the inkjet method is conveyed to the conveying surface of the conveying belt 11. In addition, the suction device 15 is driven. According to this, the air in the through holes of the conveying belt 11 and the through holes of the conveying plate 13 is sucked as described above, and the upper part of the conveying surface of the conveying belt 11 becomes negative pressure. As a result, the medium is adsorbed to the conveying surface. In this way, the medium is conveyed in the conveying direction while being adsorbed to the conveying surface of the conveying belt 11.

[0036] In addition, the control unit 51 drives the heating device 5. Accordingly, the air sucked by the air supply fan is conveyed downward. The conveyed air is heated by the heating unit, and the heated air is blown toward the medium conveyed by the conveying device 3. Accordingly, the ink of the medium is dried. The medium with dried ink is conveyed from the conveyor belt 11 to the conveying roller pair 7, and is conveyed to the downstream side by the conveying roller pair 7. That is, the driving motor 25 rotates the active roller 21, and the driven roller 23 rotates following the medium conveyed by the rotation of the active roller 21. The rotation of the driven roller 23 is detected by the rotation detection sensor 41. The detection result of the rotation detection sensor 41 is sent to the control unit 51.

[0037] The control unit 51 calculates the rotation period of the driven roller 23 based on the detection result of the rotation detection sensor 41. The control unit 51 compares the calculated rotation period with the stored reference rotation period P. In addition, the control unit 51 determines whether the motor 25 for driving the active roller 21 is being driven. When the control unit 51 determines that the calculated rotation period is longer than the reference rotation period P and the motor 25 is being driven, the driving of the heating device 5 is stopped.

[0038] That is, Figure 3B As shown in FIG. 1 , when the output waveform of the rotation detection sensor 41 continues to be “0” indicating an off signal after “1” indicating an on signal appears, the control unit 51 determines that the driven roller 23 is not rotating. Figure 3A As shown, when the driven roller 23 does not rotate even when the driving roller 21 rotates, the driven roller 23 does not rotate following the medium, and it can be determined that the medium S is not conveyed. In this case, the medium S stays in the heating device 5, so the driving of the heating device 5 is stopped.

[0039] In addition, the case where the calculated rotation period is longer than the reference rotation period P (rotation period during normal conveying operation) includes the case where, as in the above case, after the "1" indicating the on signal appears, the "0" indicating the off signal continues. Alternatively, there is also a case where the output waveform of the rotation detection sensor 41 continues to maintain "1". This case refers to the case where the rotation of the driven roller 23 stops in a state where the light emitted from the rotation detection sensor 41 is roughly perpendicularly incident on the flat surface 31a of the end 31 of the rotating shaft of the driven roller 23. This case is also included in the case where the calculated rotation period is longer than the reference rotation period P.

[0040] As described above, the control unit 51 is an example of a main roller rotation detection unit that detects the rotation of the main roller 21 in the present invention, and the rotation detection sensor 41 is an example of a driven roller rotation detection unit that detects the rotation of the driven roller 23 .

[0041] Or, if Figure 4C As shown in FIG. 1 , the control unit 51 stops the driving of the heating device 5 when it is determined that the rotation period P1 of the rotation detection sensor 41 is longer than the reference rotation period P and the motor 25 is driving. That is, when the rotation period P1 of the rotation detection sensor 41 is longer than the reference rotation period P, as shown in FIG. Figure 4A and Figure 4B As shown, even if the driving roller 21 rotates, the rotation speed of the driven roller 23 that rotates following the medium S is slow, and it can be determined that the conveying speed of the medium S is slow. In this case, for the long medium S, the time for conveying the medium S in the heating device 5 becomes longer, so the control unit 51 stops driving the heating device 5.

[0042] As can be seen from the above description, according to the drying device 1 of the present invention, by detecting the rotation of the driven roller 23 that rotates driven by the medium, it is possible to accurately and quickly detect the stop of the medium conveyance and the reduction of the medium conveyance speed. In addition, when such poor conveyance is detected, the heating device 5 is quickly stopped, thereby avoiding the situation where the medium stays in the high-temperature heating device 5.

[0043] In addition, the end portion 31 of the driven roller 23 may be processed so that the glossiness of the flat surface 31a is higher than that of the curved surface 31b. For example, a paint having a high glossiness may be applied to the flat surface 31a, and a paint having a lower glossiness than the paint may be applied to the curved surface 31b. In this case, the difference in the amount of light received by the light receiving portion of the rotation detection sensor 41 between the flat surface 31a and the curved surface 31b becomes larger, so that the rotation of the driven roller 23 can be more accurately grasped.

[0044] Next, refer to Figure 5A and Figure 5B FIG. 2 shows a modified example of the driven roller 23. In this modified example, Figure 5A and Figure 5BAs shown in FIG. 1 , the cross section of the end portion 31 of the rotating shaft of the driven roller 23 is formed into a polygon (a square in this example). That is, on the end portion 31, four flat surfaces 31a are formed at equal center angles along the circumferential direction. In this case, as shown in FIG. Figure 4A As shown, when the light emitted from the rotation detection sensor 41 is reflected substantially vertically by the flat surface 31a, the rotation detection sensor 41 outputs an on signal, such as Figure 4B As shown, when the light emitted from the rotation detection sensor 41 is not reflected substantially vertically by the flat surface 31 a , the rotation detection sensor 41 outputs an OFF signal.

[0045] In this example, if Figure 5C As shown, since the ON signal is output four times every time the driven roller 23 rotates once, the rotation period P2 is 1 / 4 of the reference rotation period P. Therefore, the medium conveyance failure determined based on the rotation period can be detected more quickly.

[0046] Furthermore, in the present embodiment, the rotation detection sensor 41 receives light reflected by the D-cut flat surface 31a in the end portion 31 of the rotation shaft of the driven roller 23. However, a pulse plate may be provided on the rotation shaft of the driven roller 23, and the rotation detection sensor 41 may receive light reflected by the reflection surface of the pulse plate. However, by receiving light reflected by the D-cut flat surface 31a as in the present embodiment, the rotation detection sensor 41 can be provided in a relatively narrow space within the length range of the rotation shaft of the driven roller 23.

[0047] The present invention records specific embodiments, but the present invention is not limited to the above embodiments. Various changes, substitutions, and deformations can be made to the above embodiments without departing from the scope and spirit of the present invention, and the scope of the technical solution includes all embodiments that can be included in the technical idea.

Claims

1. A drying device, characterized in that: It has a conveying device, a heating device, a conveying roller pair, an active roller rotation detection unit, a driven roller rotation detection unit and a control unit, wherein: The conveying device conveys the medium having an image formed thereon by ink along a prescribed conveying direction; The heating device dries the ink of the medium transported by the transport device under a high temperature environment; The conveying roller pair is arranged at a position downstream of the heating device in the conveying direction, and includes a driving roller that is driven to rotate and a driven roller that rotates following the driving roller, and is used to convey the medium passing through the heating device; The active roller rotation detection unit is used to detect the rotation of the active roller; The driven roller rotation detection unit is used to detect the rotation of the driven roller; The control unit stops the heating device when the rotation of the main roller is detected by the main roller rotation detection unit and a rotation cycle of the driven roller obtained based on the detection result of the driven roller rotation detection unit is longer than a certain cycle.

2. The drying device according to claim 1, characterized in that: The certain period is determined based on the time when a malfunction occurs in the medium due to the heating device.

3. The drying device according to claim 1, characterized in that: The driven roller rotation detection unit is a reflection type sensor having an emitting unit and a light receiving unit, wherein the emitting unit is used to emit light toward the end of the rotating shaft of the driven roller; and the light receiving unit is used to receive the light emitted from the emitting unit and reflected by the end.

4. The drying device according to claim 3, characterized in that: The end of the rotating shaft of the driven roller has a flat surface parallel to the axial direction of the rotating shaft and a curved surface along the circumferential direction of the rotating shaft. The driven roller rotation detection unit detects the rotation of the driven roller by receiving, by the light receiving unit, the light emitted from the emission unit and reflected by the flat surface.

5. The drying device according to claim 4, characterized in that: The glossiness of the flat surface is higher than that of the curved surface.

6. The drying device according to claim 3, characterized in that: The end of the rotating shaft of the driven roller has a plurality of flat surfaces formed at equal intervals along the circumferential direction of the rotating shaft and parallel to the axial direction of the rotating shaft, and the cross section is formed into a polygonal shape. The driven roller rotation detection unit detects the rotation of the driven roller by receiving, by the light receiving unit, the light emitted from the emission unit and reflected by the plurality of flat surfaces.

7. The drying device according to claim 1, characterized in that: A motor is also provided, the motor being used to rotate the driving roller, The control unit is used to drive the motor or stop the driving. The driving roller rotation detecting section is the control section.

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