Ink jet recording device

Abstract

To properly keep a temperature in a nip section.SOLUTION: An ink jet recording device includes: an ink image formation section which forms an ink image on a recording material; and a fixing device which fixes the ink image on the recording material while holding and conveying the recording material. The fixing device has a first belt which is rotatable and comes into contact with the ink image formed by the ink image formation section, a second belt which forms a nip section by abutting on the first belt, a first roller unit which has a plurality of rollers which abut on an inner peripheral surface of the first belt and suspends the first belt, a second roller unit which has a plurality of rollers which abut on an inner peripheral surface of the second belt and suspends the second belt, a first heater unit which is arranged on the inner peripheral surface of the first belt and heats the nip section by non-contact, and a second heater unit which heats the inner peripheral surface of the second belt by non-contact.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an inkjet recording apparatus for forming an ink image on a recording material. [Background technology]

[0002] If you touch a recording material immediately after it has been recorded by an inkjet recording device while the ink is still wet, the image may be distorted or the ink may get on your hands. Inkjet recording devices have a high recording speed, and a second sheet of recording material may be placed on top of the first before the ink on the first sheet has dried, causing the back side of the first sheet to become dirty. For this reason, inkjet recording devices, particularly high-speed recording models, require a means to dry the ink and fix it on the recording material.

[0003] Inkjet recording devices use a thermal fixing method in which the recording material is heated immediately after recording as a means for drying and fixing the ink. Patent Document 1 discloses a configuration in which a nip is formed by a pair of rollers to perform fixing.

[0004] In a configuration in which the recording material carrying the ink image is fixed by passing it through a nip portion formed by a pair of rollers, the width of the recording material in the conveying direction is small. Therefore, it is necessary to set the temperature of the fixing portion high. This can cause the ink image to evaporate, which can lead to image defects. For this reason, a configuration in which the nip portion is formed between belts has been proposed. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication 2010-201817 Summary of the Invention [Problem to be solved by the invention]

[0006] A fixing device is proposed in which a nip is formed by a first belt that contacts the front side of a recording material on which an ink image is formed and a second belt that contacts the first belt. In the fixing device, it is proposed that a heater, which is a heat source, is disposed on the inner peripheral surface of the first belt.

[0007] Because the nip formed by the belt pair is longer than the roller pair, the recording material and the second belt spend a lot of time absorbing heat from the first belt. This makes it difficult to maintain an appropriate temperature in the nip, as the temperature of the first belt drops easily. This can result in poor fixing, where the ink image cannot be fixed properly to the recording material.

[0008] An object of the present invention is to maintain an appropriate temperature within the nip. [Means for solving the problem]

[0009] In consideration of the above problems, an inkjet recording apparatus according to the present invention is characterized in that it comprises: an ink image forming section which forms an ink image on a recording material; a fixing device which is arranged downstream of the ink image forming section in the transport direction of the recording material and which fixes the ink image onto the recording material while nipping and transporting the recording material; the fixing device comprising: a first belt which is rotatable and contacts the ink image formed by the ink image forming section; a second belt which forms a nip portion by contacting the first belt; a first roller unit which contacts an inner circumferential surface of the first belt and has a plurality of rollers which suspend the first belt; a second roller unit which contacts an inner circumferential surface of the second belt and has a plurality of rollers which suspend the second belt; a first heater unit which is arranged on the inner circumferential surface of the first belt and which heats the nip portion without contact; and a second heater unit which heats the inner circumferential surface of the second belt without contact. Effect of the Invention

[0010] According to the present invention, the temperature in the nip portion can be kept at an appropriate level, and productivity can be improved. [Brief description of the drawings]

[0011] [Figure 1] 1 is a schematic configuration diagram of an image forming system according to an embodiment of the present invention. [Diagram 2] 1 is a diagram showing the overall configuration of a fixing system in an inkjet recording apparatus according to a first embodiment, including a first belt unit 10 and a second belt unit belt 20. FIG. [Diagram 3] FIG. 2 is a diagram showing a configuration of a temperature sensor for adjusting the temperature of the fixing system and a temperature sensor for stopping a heater. [Figure 4] 2 is a hardware block diagram of a first belt unit 10 of the fixing system of the first embodiment. FIG. [Diagram 5] 4 is a flowchart of the first belt unit 10 of the fixing system according to the first embodiment. [Figure 6] 1 is a diagram showing the configuration of a thermostat 510 and a roller 710. FIG. [Figure 7] FIG. 4 is a diagram showing a configuration of a temperature sensor for adjusting the temperature of the lower fixing system and a temperature sensor for stopping a heater. [Figure 8] FIG. 2 is a hardware block diagram of a second belt unit 20 of the fixing system of the first embodiment. [Figure 9] 4 is a flowchart of the second belt unit 20 of the fixing system according to the first embodiment. [Figure 10] This is a diagram showing a thermostat disposed on the outside of the first belt. [Figure 11] This is a diagram showing a thermostat disposed on the outside of the second belt. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] <Example 1> The present embodiment will be described with reference to the drawings. First, a schematic configuration of an image forming system according to the present embodiment will be described with reference to FIG.

[0013] <Image forming system> The inkjet recording apparatus 100 of this embodiment uses an inkjet recording method in which ink is ejected to form an image on a recording material. An ink image is formed on the recording material using two liquids, a reaction liquid and ink. The recording material S may be any recording material capable of receiving ink, such as plain paper, thick paper, plastic film for overhead projectors, specially shaped recording materials such as envelopes and index paper, and cloth.

[0014] 1, an inkjet recording apparatus 100 according to the present embodiment is an example of an image forming apparatus, and includes a feeding module 1000, an ink image forming unit 2000, and a drying module 3000. The inkjet recording apparatus 100 further includes a fixing device 4000, a cooling module 5000, an inverting module 6000, and a stacking module 7000. The recording material S supplied from the feeding module 1000 is subjected to various processes while being transported along a transport path within each module, and is finally discharged to the stacking module 7000.

[0015] The feeding module 1000 to the loading module 7000 may each have a separate housing, and these housings may be connected to configure the inkjet recording apparatus 100. Alternatively, the feeding module 1000 to the loading module 7000 may be arranged in a single housing.

[0016] The feeding module 1000 has storage chambers 1100a, 1100b, and 1100c for storing recording materials S, and the storage chambers 1100a to 1100c are provided so as to be able to be pulled out toward the front side of the apparatus in order to store the recording materials S. The recording materials S are fed one by one in each of the storage chambers 1100a to 1100c by a separation belt and a transport roller, and are transported to the ink image forming unit 2000. Note that the feeding module 1000 is not limited to a configuration having three storage chambers 1100a to 1100c, and may be a configuration having one, two, or four or more storage chambers.

[0017] The ink image forming unit 2000 has a pre-image registration correction unit, a print belt unit 2200, and a recording unit 2300, and ejects ink onto the recording material S to form an ink image. The recording material S conveyed from the feeding module 1000 has its inclination and position corrected by the pre-image registration correction unit, and is conveyed to the print belt unit 2200. The recording unit 2300 is disposed at a position facing the print belt unit 2200 with respect to the conveying path. The recording unit 2300 is an inkjet recording unit that forms an ink image by ejecting ink onto the conveyed recording material S from above using a recording head. A plurality of recording heads that eject ink are arranged along the conveying direction. In this embodiment, in addition to the four colors of Y (yellow), M (magenta), C (cyan), and Bk (black), a total of five line-type recording heads corresponding to the reaction liquid are provided. The recording material S is adsorbed and conveyed by the print belt unit 2200, so that a clearance between the recording head and the recording material S is ensured.

[0018] The number of ink colors and recording heads are not limited to the above five. The inkjet method may be a method using a heating element, a method using a piezoelectric element, a method using an electrostatic element, a method using a MEMS (Micro Electro Mechanical Systems) element, or the like. Each color of ink is supplied to the recording head from an ink tank (not shown) via an ink tube. The ink contains a resin component of "0.1% by mass to 20.0% by mass" based on the total mass of the ink, water, a water-soluble organic solvent, a coloring material, wax, additives, and the like.

[0019] When the recording material S on which an image is formed by the recording section 2300 is transported by the print belt unit 2200, it is detected by an in-line scanner (not shown) arranged downstream of the recording section 2300 in the transport direction of the recording material S. Here, the misalignment and color density of the image formed on the recording material S are detected, and the image formed on the recording material S, density, etc. are corrected based on the misalignment and color density of the image.

[0020] The drying module 3000 is an example of a drying device, and dries the recording material S on which an image is formed by ejecting ink by blowing hot air onto the recording material S. The drying module 3000 has a decoupling section 3200, a drying belt unit 3300, and a hot air blowing unit 3400. The drying module 3000 reduces the liquid content of the ink and reaction liquid applied to the recording material S in order to improve the fixation of the ink to the recording material S by the subsequent fixing device 4000. The recording material S on which the image is formed is transported to the decoupling section 3200 arranged in the drying module 3000. In the decoupling section 3200, a frictional force is generated between the recording material S and the belt by the wind pressure of the wind blown from above, and the recording material S is transported by the belt. In this way, the recording material S placed on the belt is transported by the frictional force, thereby preventing the recording material S from shifting when the recording material S is transported between the print belt unit 2200 and the decoupling section 3200. The recording material S transported from the decoupling section 3200 is adsorbed and transported by the drying belt unit 3300, and the ink and reaction liquid applied to the recording material S are dried by hot air blown onto it from the hot air blowing unit 3400 arranged above the belt.

[0021] In this way, the ink and reaction liquid applied to the recording material S are heated by the drying module 3000, accelerating the evaporation of moisture. This makes it possible to suppress the occurrence of so-called cockling, in which the ink applied to the recording material S absorbs the ink and the paper locally stretches and wrinkles. As a heater for heating the air, heating by, for example, an electric heating wire or an infrared heater is preferable from the standpoint of safety and energy efficiency. Furthermore, the drying method may be configured by combining a method of applying hot air, a method of irradiating the surface of the recording material S with electromagnetic waves (ultraviolet rays, infrared rays, etc.), and a conductive heat transfer method by contact with a heating element.

[0022] The fixing device 4000 has a fixing belt unit 4100. The fixing belt unit 4100 passes the recording material S, on which an image has been formed and which has been conveyed from the drying module 3000, through a nip portion formed between a heated first belt unit and a second belt unit. As a result, the ink image is fixed onto the recording material S.

[0023] The cooling module 5000 has a plurality of cooling sections 5001, which cool the high-temperature recording material S transported from the fixing device 4000. The cooling section 5001, for example, takes in outside air into a cooling box with a fan to increase the pressure inside the cooling box, and cools the recording material S by blowing air from the cooling box through a nozzle due to the pressure onto the recording material S. The cooling sections 5001 are disposed on both sides of the transport path of the recording material S, and cool both sides of the recording material S.

[0024] The cooling module 5000 is provided with a transport path switching unit 5002. The transport path switching unit 5002 switches the transport path of the recording material S depending on whether the recording material S is transported to the reversing module 6000 or to a double-sided transport path for double-sided printing in which images are formed on both sides of the recording material S.

[0025] The inversion module 6000 has an inversion section 6400. The inversion section 6400 inverts the recording material S being conveyed, and changes the orientation of the recording material S when it is discharged to the stacking module 7000. The stacking module 7000 has a top tray 7200 and a stacking section 7500, and stacks the recording material S conveyed from the inversion module 6000.

[0026] During double-sided printing, the recording material S is conveyed to a conveying path below the cooling module 5000 by the conveying path switching unit 5002. Thereafter, the recording material S passes through a double-sided conveying path including the fixing device 4000, the drying module 3000, the ink image forming unit 2000, and the feeding module 1000, and is returned to the ink image forming unit 2000. The double-sided conveying unit of the fixing device 4000 is provided with an inverting unit 4200 that inverts the recording material S. The recording material S returned to the ink image forming unit 2000 has an image formed with ink on the other side on which no image is formed, and is then discharged from the drying module 3000 through the inverting module 6000 to the stacking module 7000.

[0027] <Fixing device> 2 is an overall configuration diagram including a first belt unit 10 and a second belt unit 20 of a fixing device 4000 in an inkjet recording apparatus of the first embodiment. The inkjet recording apparatus prints inkjet onto a recording material S, dries moisture in the inkjet, and fixes the ink. A rotatable first belt 30 of the first belt unit 10 is heated by a heat source, and contacts and heats the recording material S. A rotatable second belt 40 of the second belt unit forms a nip portion by contacting the first belt 30. The first belt 30 and the second belt 40 sandwich and transport the recording material S, and fix the recording material S.

[0028] The first belt 30 and the second belt 40 are rotated by drive motors (not shown) which are their respective drive sources, and the recording material S is transported in the direction of the arrow. A drive motor is connected to the first drive roller 720 and driven to rotate, thereby rotating the first belt 30. A drive motor is connected to the second drive roller 740 and driven to rotate, thereby rotating the second belt 40. The first drive motor and the second drive motor are rubber rollers with rubber surfaces. Being rubber rollers increases the gripping force on the belt, allowing the belt to be transported stably.

[0029] <First belt unit> The first belt unit 10 includes heaters 110, 120, and 130, a first roller unit having a plurality of rollers, temperature sensors 210, 220, and 230, and a temperature sensor 310 that adjusts the temperature of the belt.

[0030] The first belt 30 comes into contact with the front surface of the recording material S on which ink has been applied by the ink image forming unit 2000. In order to heat the ink image on the recording material S, a first heater unit 160 is arranged to heat the inner circumferential surface of the first belt 30 without contact. The first heater unit has heaters 110, 120, and 130 which are halogen heaters, and the heaters 110, 120, and 130 heat the inner circumferential surface of the first belt without contact. The heaters 110, 120, and 130 are arranged side by side along the conveying direction of the recording material S. Furthermore, the heaters 110, 120, and 130 heat the nip portion formed by the first belt 30 and the second belt 40. Therefore, the heaters 110, 120, and 130 arranged on the inner circumferential surface of the first belt are arranged side by side along the conveying direction in the nip portion. The nip portion of this embodiment is configured to be wide in the conveying direction so that it can be arranged along such a conveying direction.

[0031] <Temperature control and safety control of the first belt unit> The rotation detection sensor 410 is a sensor that detects whether the belt is rotating, and is disposed on the driven roller. The reason why the rotation detection sensor 410 is disposed on the driven roller is that if the rotation detection sensor 410 is disposed on the driving roller, the driving roller will rotate if the motor is driven even when the belt 30 is not attached, resulting in a false detection, so the rotation detection sensor 410 is disposed on the driven roller.

[0032] When the belt stops rotating, the rotation detection sensor 410 detects it and stops heating the heaters 110, 120, and 130. The heaters 110, 120, and 130 are covered with reflectors and heat the belt directly below the heaters 110, 120, and 130. The temperature sensors 210, 220, and 230 are safety sensors that detect the temperature of the belt area heated by the heaters 110, 120, and 130 and detect whether the temperature exceeds 150°C. The temperature sensor 310 is a sensor for detecting the temperature of the belt and adjusting the temperature of the heaters 110, 120, and 130. The temperature of 150°C is a temperature set so that the belt does not deform, and is not limited to this because it is a temperature determined according to the material of the belt. The temperature sensor 310 that adjusts the temperature of the belt adjusts the temperature to 100°C downstream of the heaters 110, 120, and 130 to achieve high print quality. The temperature of 100°C is the temperature at which the ink is fixed on the print medium, and is determined according to the material of the ink, so it is not limited to this. However, when the heaters 110, 120, 130 become higher than a predetermined temperature, it takes time for the temperature sensor 310 for adjusting the temperature to stop the heaters. Therefore, when the heaters 110, 120, 130 become higher than a predetermined temperature, the temperature sensors 210, 220, 230 detect the temperature directly below the heaters, and the heaters 110, 120, 130 can be stopped. By providing two types of sensors in this way, even when a long nip configuration is adopted, the temperature of the paper can be accurately adjusted to a predetermined temperature. Furthermore, even when the heaters 110, 120, 130 become higher than a predetermined temperature, it is possible to stop the heaters 110, 120, 130 without deforming the belt. Also, in consideration of the possibility that temperature sensors 210, 220, 230 fail and sensor 310 that regulates the belt temperature also fails, thermostat 510 is placed on first roller 710, closer to heaters 110, 120, 130 in the belt rotation direction. When the belt temperature reaches a certain level or higher, the roller detected by thermostat 510 is also heated, and when the roller temperature reaches a certain level or higher, thermostat 510 cuts off the AC lines to heaters 110, 120, 130.

[0033] 4 is a hardware block diagram of the first belt unit 10. The first belt unit 10 is composed of a CPU 1100, a Relay 1200, FETs 111, 121, and 131, overheating detection hardware 211, 221, and 231, heaters 110, 120, and 130, temperature sensors 210, 220, and 230, and a temperature sensor 310.

[0034] The CPU 1100 controls the FETs 111, 121, and 131 by ON / OFF control, driving the FETs 111, 121, and 131 to control the heaters 110, 120, and 130. The temperature sensors 210, 220, and 230 are connected to overheating detection hardware 211, 221, and 231, and the temperature sensors 210, 220, and 230 detect the temperature of 150°C or higher by a hardware circuit. This temperature of 150°C is a temperature set so that the belt does not deform, and is not limited to this because it is a temperature determined according to the material of the belt. When any of the overheating detection hardware 211, 221, and 231 detects a temperature of 150°C or higher, the control of the corresponding FET 111, 121, and 131 is stopped. When the temperature of the temperature sensor 210 is detected by the overheating detection HW 211, the control of the FET 111 is stopped, but the overheating detection HW 211 does not stop the control of the other FETs 121 and 131 by a hardware circuit. The CPU 1100 detects an interrupt signal from the overheating detection HW 211 and stops the FETs 121 and 131 by software. In this embodiment, the FETs are stopped by the CPU, but they may be stopped by a hardware circuit. The thermostat 510 cuts off the AC line from the Relay 1200 when the temperature exceeds a predetermined temperature.

[0035] 5 is a flowchart of the first belt unit 10. When the fixing control is started, the process proceeds to S101.

[0036] In S101, the CPU 1100 controls the drive motor of the first belt 30 to rotate the first belt 30. The CPU 1100 also turns on the RELAY 1200.

[0037] In S102, the CPU 1100 determines whether the first belt 30 is rotating using the rotation detection sensor 410. If the CPU 1100 determines that the first belt 30 is rotating, the process proceeds to S103, and if the CPU 1100 determines that the first belt 30 is not rotating, the process proceeds to S105.

[0038] In S103, the CPU 1100 controls the temperatures of the heaters 110, 120, and 130 based on the temperature value read from the temperature sensor 310. The CPU 1100 controls the temperatures of the heaters 110, 120, and 130 by controlling the duty width of the PWM control signal for the FETs 111, 121, and 131.

[0039] In S104, if the temperature values ​​read by the CPU 1100 from the temperature sensors 210, 220, 230 are higher than the threshold temperature of 150° C., the process proceeds to S105. In S104, if the temperature values ​​read by the CPU 1100 from the temperature sensors 210, 220, 230 are lower than the threshold temperature of 150° C., the process proceeds to S102.

[0040] In S105, the CPU 1100 stops the heaters 110, 120, and 130.

[0041] As described above, the nip portion of the fixing device 4000 of this embodiment is configured to be long in the conveying direction of the recording material S. Therefore, the first belt 30 contacts the recording material S for a long time. The first belt 30 also contacts the second belt 40 for a long time. As a result, the first belt 30 is heated by the first heater unit 160, but the amount of heat that is taken away is also large. This makes it difficult to maintain the inside of the nip portion at an appropriate temperature. As a result, the recording material S and the ink image on the recording material cannot be raised to a desired temperature, and there is a risk of poor fixing. In this embodiment, a configuration for heating the second belt 40 is provided to maintain the temperature inside the nip portion at an appropriate level. A specific configuration is shown below.

[0042] <Second belt unit> The second belt unit 20 will be described with reference to FIGS.

[0043] In order to heat the recording material S itself on which the ink is applied, the second belt is composed of heaters 140, 150. By performing long nip and heating with both the first belt 30 and the second belt 40, the ink applied to the recording material S penetrates and high print quality is achieved.

[0044] The second belt unit 20 is composed of heaters 140 and 150, a second roller unit having a plurality of rollers, temperature sensors 240 and 250, and a temperature sensor 320 that adjusts the temperature of the belt.

[0045] The second belt 40 comes into contact with the back surface of the recording material S, which is the surface opposite to the front surface on which ink has been applied by the ink image forming unit 2000. In the case of double-sided printing, when the ink image forming unit 2000 forms an ink image on the back surface, the second belt 40 comes into contact with the front surface of the recording material.

[0046] The second belt unit has a second heater unit 170. The second heater unit heats the inner circumferential surface of the second belt 40. A pad member 800 is disposed on the inner circumferential surface of the second belt 40. The pad member 800 functions as a backup member for the second belt 40, since the first belt 30 and the second belt 40 form a nip portion. By disposing the pad member 800, the width of the nip portion in the transport direction can be determined with high precision, and further, the recording material can be transported stably.

[0047] Since the pad member 800 is disposed on the inner peripheral surface of the second belt, the second heater unit heats the inner peripheral surface of the second belt other than the nip portion. When the nip portion of the inner peripheral surface of the second belt is heated, the pad member 800 is directly heated, and the pad member 800 transfers heat to the second belt 40. Since the second belt 40 cannot be efficiently heated, the second heater unit 170 heats the inner peripheral surface of the second belt 40 other than the nip portion. However, in order to keep the nip portion at an appropriate temperature, the second heater unit 170 heats a position close to the nip portion even in a portion other than the nip portion. Specifically, the second heater unit 170 is disposed in a downstream half region in the conveying direction in the circumferential length of the second belt other than the nip portion.

[0048] The second belt unit 20 has heaters 140 and 150. The heaters 140 and 150 are halogen heaters. In this embodiment, the number of halogen heaters included in the first heater unit 160 is greater than the number of heaters included in the second heater unit 170. This is because the first heater unit 160 must heat the ink applied onto the recording material by the ink image forming section 2000. Accordingly, the first heater unit 160 requires a larger amount of heat than the second heater unit 170.

[0049] The rotation detection sensor 420 is a sensor that detects whether the belt is rotating or not, and is disposed on the driven roller. When the belt stops rotating, the rotation detection sensor 420 detects it and causes the heaters 140 and 150 to stop heating.

[0050] The heaters 140 and 150 are covered with reflectors and heat the belt directly below the heaters 140 and 150. The temperature sensors 240 and 250 are safety sensors that detect the temperature of the belt area heated by the heaters 140 and 150 and detect whether the temperature exceeds 150°C. The temperature of 150°C is set so that the belt does not deform, and is not limited to this because it is a temperature determined according to the material of the belt. The reflectors covering the heaters 140 and 150 open toward areas other than the nip portion. This makes it possible to heat a position that avoids the pad member 800.

[0051] The reflectors arranged on the first belt unit 10 and the second belt unit 20 open in the same direction. Arranging all the reflectors in the same direction makes installation easier.

[0052] As described above, by disposing a heater for heating the inner circumferential surface of the first belt 30 and a heater for heating the inner circumferential surface of the second belt 40, the temperature in the nip portion can be kept at an appropriate level even in this embodiment in which a long nip portion is formed, thereby improving productivity.

[0053] <Temperature control and safety control of the second belt unit> The temperature sensor 320 is a sensor for detecting the temperature of the belt and adjusting the temperature of the heaters 140 and 150. The temperature sensor 320 for adjusting the temperature of the belt adjusts the temperature downstream of the heaters 140 and 150 to 100° C., thereby realizing high print quality. This temperature of 100° C. is the temperature at which the ink is fixed to the print medium, and is determined according to the material of the ink, so it is not limited to this. However, when the heaters 140 and 150 reach a temperature higher than a predetermined temperature, it takes time for the temperature sensor 320 for adjusting the temperature to stop the heaters 140 and 150. Therefore, when the heaters 140 and 150 reach a temperature higher than the predetermined temperature, the temperature sensors 240 and 250 can detect the temperature directly below the heaters 140 and 150 to stop the heaters 140 and 150. By providing two types of sensors in this way, even when a long nip configuration is adopted, the temperature of the recording material S can be accurately adjusted to a predetermined temperature. Furthermore, even if the heaters 140, 150 reach a temperature higher than a predetermined temperature, it is possible to stop the heaters 140, 150 without deforming the belt.

[0054] Considering the possibility that temperature sensors 240, 250 and belt temperature sensor 320 also fail, thermostat 520 is arranged downstream of heaters 140, 150 in the belt rotation direction. When the belt temperature reaches a certain level or higher, thermostat 520 also heats the roller on which thermostat 520 is arranged. When the roller temperature reaches a certain level or higher, thermostat 520 cuts off the AC lines to heaters 140, 150. In this way, even if temperature sensors 240, 250, 320 fail, thermostat 520 safely cuts off the AC lines, making it possible to realize a safe fixing system.

[0055] FIG. 7 is a diagram showing the configuration of a temperature sensor.

[0056] The second belt unit 20 is composed of heaters 140, 150, temperature sensors 240, 250, and a temperature sensor 320 that adjusts the temperature of the belt. The heaters 140, 150 are covered with reflectors and heat the belt directly below the heaters 140, 150. The temperature sensors 240, 250 are safety sensors that detect the temperature of the belt area heated by the heaters 140, 150 and check whether the temperature exceeds a certain threshold temperature. The temperature sensor 320 is a sensor that detects the temperature of the belt and adjusts the temperature of the heaters 140, 150.

[0057] 8 is a hardware block diagram of the second belt unit 20. The second belt unit 20 is composed of a CPU 2100, a Relay 2200, FETs 411 and 421, overheating detection hardware 511 and 521, heaters 140 and 150, temperature sensors 510 and 520, and a temperature sensor 320. The CPU 2100 controls the FETs 411 and 421 by ON / OFF control, and drives the FETs 411 and 421 to control the heaters 140 and 150. The temperature sensors 510 and 520 are connected to the overheating detection hardware 511 and 521, and the temperature sensors 510 and 520 detect the temperature of 150° C. or higher by a hardware circuit. The temperature of 150° C. is a temperature set so that the belt does not deform, and is not limited to this because it is a temperature determined according to the material of the belt. When either of the overheat detection HW511, 521 detects a temperature of 150° C. or higher, it stops control of the corresponding FET411, 421. When the overheat detection HW511 detects the temperature of the temperature sensor 320, it stops control of the FET411, but the overheat detection HW511 does not stop control of the other FET421 by hardware circuitry. The CPU2100 detects the interrupt signal of the overheat detection HW511 and stops the FET421 by software. In this patent, the FET is stopped by the CPU, but it may be stopped by hardware circuitry. The thermostat 520 cuts off the AC line from the Relay2200 when the temperature exceeds a predetermined temperature.

[0058] 9 is a flowchart of the second belt unit 20. When the fixing control is started, the process proceeds to S201.

[0059] In S201, the CPU 2100 controls the drive motor of the second belt 40 to rotate the second belt 40. The CPU 2100 also turns on the RELAY 2200.

[0060] In S202, the CPU 2100 determines whether the second belt 40 is rotating using the rotation detection sensor 420. If the CPU 2100 determines that the second belt 40 is rotating, the process proceeds to S203, and if the CPU 2100 determines that the second belt 40 is not rotating, the process proceeds to S205.

[0061] In S203, the CPU 2100 controls the temperatures of the heaters 140, 150 based on the temperature value read from the temperature sensor 320. The CPU 2100 controls the heaters 140, 150 by controlling the temperature of the FETs 141, 151 with the duty width of the PWM control signal.

[0062] In S204, if the temperature value read by the CPU 2100 from the temperature sensors 240, 250 is higher than the threshold temperature of 150° C., the process proceeds to S205. In S204, if the temperature value read by the CPU 2100 from the temperature sensors 240, 250 is lower than the threshold temperature of 150° C., the process proceeds to S202.

[0063] In S205, the CPU 2100 stops the heaters 140 and 150.

[0064] <Example 2> In the second embodiment, a configuration will be described in which a thermostat is provided to quickly detect heater runaway when the runaway occurs.

[0065] A heat source for heating the belt is provided in the fixing device 400. A thermostat is provided in case the heater, which is the heat source, goes out of control. The thermostat is a non-contact temperature detection member, and as described in the first embodiment, cuts off the AC line when it detects a predetermined temperature.

[0066] In the fixing device 4000 of the present embodiment, which forms a long nip in the conveying direction, the distance between the rollers that suspend the belt becomes long. This causes the belt to bend. In such a configuration, when a thermostat tries to detect the temperature of the belt, the distance between the belt and the thermostat varies. This variation may prevent the thermostat from detecting the temperature of the belt with high accuracy, and may prevent the thermostat from detecting the heater runaway promptly.

[0067] To address the above-mentioned issues, a thermostat is provided on the roller in the second embodiment, the details of which are described below.

[0068] FIG. 3 is a diagram showing the configuration of the temperature sensor of the first belt unit 10. As shown in FIG.

[0069] The first belt unit 10 is composed of heaters 110, 120, 130, temperature sensors 210, 220, 230, and a temperature sensor 310 that adjusts the temperature of the belt. The heaters 110, 120, 130 are covered with reflectors and heat the belt directly below the heaters 110, 120, 130. The temperature sensors 210, 220, 230 are safety sensors that detect the temperature of the belt area heated by the heaters 110, 120, 130 and detect whether the temperature exceeds a certain threshold temperature. The temperature sensor 310 is a sensor that detects the temperature of the belt and adjusts the temperature of the heaters 110, 120, 130.

[0070] Thermostat 510 (first temperature detection member) is disposed so as to detect the temperature of the roller that suspends first belt 30. It detects the temperature of first roller 710 shown in FIG. 2 in a non-contact manner. The first roller is disposed downstream of heaters 110, 120, 130 in the conveying direction of the recording material. The area of ​​first belt 30 heated by heaters 110, 120, 130 comes into contact with first roller 710 first. This is because by being disposed in a position close to heaters 110, 120, 130, runaway of heaters 110, 120, 130 can be detected as soon as possible.

[0071] In addition, the first roller 710 is a metal roller with a metal surface. By making the surface metal, the thermal response is improved, and heat is easily transferred from the first belt 30. This makes it possible to quickly detect runaway of the heaters 110, 120, and 130.

[0072] 6 is a diagram showing the configuration of the thermostat 510 and the roller 710. The thermostat 510 detects the temperature of the roller 710 in a non-contact manner. The thermostat 510 is disposed at a certain distance from the roller 710.

[0073] 10 is a diagram showing a thermostat 510 disposed on the outer side of the first belt 30. The thermostat 510 is disposed on the outer side of the first belt 30.

[0074] 11 is a diagram showing a case in which the thermostat 520 is disposed on the outer side of the second belt 40. The thermostat 520 is disposed on the outer side of the second belt 40. [Explanation of symbols]

[0075] 10 First belt unit 20 Second belt unit 30 First Belt 40 Second Belt 100 Inkjet recording device 110, 120, 130, 140, 150 Heater 160 First heater unit 170 Second heater unit 210, 220, 230, 240, 250, 310, 320 Temperature Sensors 510, 520 Thermostat (first temperature detection member) 710 First Roller 800 Pad material 4000 Fixing device

Claims

1. an ink image forming unit that forms an ink image on a recording material; a fixing device disposed downstream of the ink image forming unit in a conveying direction of the recording material, the fixing device fixing the ink image onto the recording material while nipping and conveying the recording material; The fixing device is a first belt that is rotatable and contacts the ink image formed by the ink image forming section; a second belt that contacts the first belt to form a nip portion; a first roller unit having a plurality of rollers that contact an inner circumferential surface of the first belt and suspend the first belt; a second roller unit having a plurality of rollers that contact an inner circumferential surface of the second belt and suspend the second belt; a first heater unit disposed on an inner circumferential surface of the first belt and configured to heat the nip portion in a non-contact manner; a second heater unit that heats an inner circumferential surface of the second belt in a non-contact manner; having 1. An ink jet recording apparatus comprising:

2. the fixing device has a pad member disposed on an inner circumferential surface of the second belt and forming the nip portion together with the first belt via the second belt; 2. The inkjet recording apparatus according to claim 1,

3. the second heater unit heats an inner circumferential surface of the second belt other than the nip portion; 3. The inkjet recording apparatus according to claim 2,

4. The first heater unit has a plurality of halogen heaters, The second heater unit has a plurality of halogen heaters.

4. The inkjet recording apparatus according to claim 3,

5. The halogen heater of the first heater unit is disposed along the transport direction.

5. The inkjet recording apparatus according to claim 4,

6. The number of halogen heaters included in the first heater unit is greater than the number of halogen heaters included in the second heater unit.

6. The inkjet recording apparatus according to claim 5,

7. The first heater unit and the second heater unit each have a reflector.

7. The inkjet recording apparatus according to claim 6,

8. The reflectors of the first heater unit and the second heater unit are open in the same direction.

8. The inkjet recording apparatus according to claim 7,

9. the first roller unit has a first roller disposed downstream of the nip portion in the transport direction, A first temperature detection member that detects the temperature of the first roller.

2. The inkjet recording apparatus according to claim 1,

10. The first temperature detection member is in non-contact with the first roller.

10. The inkjet recording apparatus according to claim 9,

11. The first roller is a metal roller.

11. The inkjet recording apparatus according to claim 10.

12. The first roller unit has a drive roller that is connected to a drive source and is driven to rotate, and the drive roller has a rubber surface.

12. The inkjet recording apparatus according to claim 11.

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