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JP-2026074596-A - Inkjet recording device

JP2026074596AJP 2026074596 AJP2026074596 AJP 2026074596AJP-2026074596-A

Abstract

[Problem] To reduce the number of heaters used to heat the belt and enable each heater to operate at a temperature suitable for its intended use. [Solution] The total duty cycle is calculated according to the temperature difference between the belt temperature detected by the belt temperature sensor and the target temperature (S2), and the heaters to be used for heating operation are determined from among the multiple heaters based on the total duty cycle (S3, S5, S7). The smaller the total duty cycle, that is, the smaller the temperature difference between the belt temperature and the target temperature, the fewer heaters are used for heating operation (S4, S6, S7). A PWM signal with a duty cycle corresponding to the total duty cycle is generated for the heaters to be used for heating operation, and a PWM signal with a duty cycle of "0%" is generated for the heaters that are not used for heating operation, and these are output individually to the corresponding FETs. By outputting a PWM signal with a duty cycle of "0%", the FETs are not turned on and off according to the PWM signal, and the shortening of the heater lifespan can be suppressed. [Selection Diagram] Figure 7

Inventors

  • 山口 悠介
  • 千代田 保▲晴▼
  • 中山 敏則
  • 松浦 大悟
  • 齋藤 秀太郎
  • 青木 孝平
  • 岡田 祐太朗

Assignees

  • キヤノン株式会社

Dates

Publication Date
20260507
Application Date
20241021

Claims (10)

  1. An image forming unit that ejects ink to form an image on a sheet, The endless first belt, An endless second belt that contacts the first belt and forms a nip portion for gripping, transporting, and heating a sheet on which an image has been formed by the image forming unit, A plurality of heating elements are arranged on the inner circumference of the first belt along the sheet conveying direction and heat the first belt, A power supply circuit that supplies power to the plurality of heating elements, A temperature detection unit for detecting the temperature of the first belt, The system includes a control unit that generates a plurality of PWM signals for each of the plurality of heating elements, which control the power supply circuit by pulse width modulation so that the temperature of the first belt detected by the temperature detection unit becomes a predetermined target temperature, and which can individually control the power supplied from the power supply circuit to the plurality of heating elements using the generated plurality of PWM signals, The control unit, based on the plurality of PWM signals, If the temperature difference between the temperature of the first belt and the target temperature is greater than or equal to a threshold, two or more of the heating elements are made to generate heat. When the temperature difference is smaller than the threshold, fewer heating elements are generated than when the temperature difference is greater than or equal to the threshold. An inkjet recording apparatus characterized by the following features.
  2. The control unit generates a plurality of PWM signals with different duty cycles based on at least the temperature difference between the temperature of the first belt and the target temperature. The inkjet recording apparatus according to feature 1.
  3. The control unit generates heat in a predetermined number of heating elements according to the temperature difference. The inkjet recording apparatus according to feature 1.
  4. The control unit generates a PWM signal with a duty cycle of "0%" with respect to the heating element that is not generating heat among the plurality of heating elements. The inkjet recording apparatus according to feature 1.
  5. The control unit generates the PWM signal with the same duty cycle of a predetermined value or more with respect to the heating element that generates heat among the plurality of heating elements, according to the temperature difference. The inkjet recording apparatus according to feature 1.
  6. The aforementioned predetermined value is "30%" or more. The inkjet recording apparatus according to feature 5.
  7. The system includes a timing unit that counts the time each of the multiple heating elements is generating heat and measures the cumulative time. The plurality of heating elements are heated in order from the heating element with the shortest cumulative time measured by the timing unit. The inkjet recording apparatus according to feature 1.
  8. The aforementioned heating element is a halogen heater that emits infrared radiation to generate heat. The inkjet recording apparatus according to feature 1.
  9. The aforementioned multiple heating elements are, firstly, heating elements. The aforementioned power supply circuit is the first power supply circuit, The temperature detection unit is a first temperature detection unit, A plurality of second heating elements are arranged on the inner circumference of the second belt along the sheet conveying direction and heat the second belt, A second power supply circuit that supplies power to the plurality of second heating elements, It comprises a second temperature detection unit that detects the temperature of the second belt, The control unit generates a plurality of second PWM signals for each of the plurality of second heating elements to control the second power supply circuit by pulse width modulation so that the temperature of the second belt detected by the second temperature detection unit becomes the target temperature, and the power supplied from the second power supply circuit to the plurality of second heating elements can be individually controlled by the plurality of second PWM signals generated. The control unit, based on the plurality of second PWM signals, If the temperature difference between the temperature of the second belt and the target temperature is greater than or equal to the threshold, two or more of the second heating elements are made to generate heat. When the temperature difference between the temperature of the second belt and the target temperature is less than the threshold, the second heating element is heated in fewer units than when the temperature difference between the temperature of the second belt and the target temperature is greater than or equal to the threshold. The inkjet recording apparatus according to feature 1.
  10. The control unit generates a plurality of second PWM signals with different duty cycles based on at least the temperature difference between the temperature of the second belt and the target temperature. The inkjet recording apparatus according to feature 9.

Description

This invention relates to an inkjet recording apparatus that forms an image on a sheet using ink. In an inkjet recording device that forms an image on a sheet using ink, a method has been proposed in which heat and pressure are applied to the sheet using a pair of belts that come into contact with each other to fix the ink to the sheet. By using a pair of belts, the nip length of the fixing nip section, which holds and transports the sheet and fixes the ink to the sheet, can be ensured, thereby improving the ink's ability to adhere to the sheet. In inkjet recording devices, a low-heat-capacity belt is directly heated by multiple halogen heaters to raise the belt temperature to the target temperature as quickly as possible. The temperature of these heaters is adjusted as needed according to the results of a temperature sensor that detects the belt temperature. Conventionally, as in the device described in Patent Document 1, the heater temperature is controlled by rapidly switching the switching elements of the power supply circuit that supplies the voltage to operate the heaters on and off according to a PWM (Pulse Width Modulation) signal (PWM control). The heater temperature fluctuates up or down according to the duty cycle of the PWM signal. Japanese Patent Publication No. 2018-77265 A schematic diagram showing the inkjet recording apparatus of this embodiment.A schematic diagram showing the fixing module.A schematic diagram showing the heating section.(a) A diagram showing the heater temperature sensor, (b) A diagram explaining the field of view of the heater temperature sensor, (c) A graph explaining the relationship between temperature measurement accuracy and field of view.(a) A diagram illustrating the heating intensity of the heater at a position in the belt width direction, (b) A graph showing the change in belt temperature over time.(a) Block diagram showing the heater temperature control system, (b) Block diagram showing the power supply circuit that supplies power to the lower heater.A flowchart showing the heater control process of the first embodiment.A flowchart illustrating a conventional heater control process.A graph showing the time variation of belt temperature and the duty cycle of the PWM signal output to each heater in a conventional example.A graph showing the time variation of the belt temperature and the duty cycle of the PWM signal output to each heater in this embodiment.A flowchart showing the heater control process of the second embodiment. [First Embodiment] <Inkjet recording device> Embodiments of the present invention will be described in detail below with reference to the drawings. Figure 1 is a schematic diagram showing an inkjet recording apparatus of this embodiment. The inkjet recording apparatus 1 shown in Figure 1 is a so-called sheet-fed inkjet recording apparatus that forms an ink image on a sheet S using two liquids, a reaction solution and ink. The sheet S can be any recording material that can accept ink, such as paper like plain paper or cardboard, plastic film such as an overhead projector sheet, specially shaped recording material such as an envelope or index paper, or cloth. As shown in Figure 1, the inkjet recording device 1 comprises a paper feed module 1000, a print module 2000, a drying module 3000, a fixing module 4000, a cooling module 5000, a reversing module 6000, and a loading module 7000. The sheets S supplied from the paper feed module 1000 undergo various processing as they are transported along the transport path within each module, and are finally discharged into the loading module 7000. The paper feed module 1000, print module 2000, drying module 3000, fuser module 4000, cooling module 5000, inversion module 6000, and stacking module 7000 may each have separate housings, and these housings may be connected to constitute the inkjet recording device 1. Alternatively, the paper feed module 1000, print module 2000, drying module 3000, fuser module 4000, cooling module 5000, inversion module 6000, and stacking module 7000 may be arranged in a single housing. The paper feed module 1000 has storage compartments 1500a, 1500b, and 1500c for storing sheets S. Storage compartments 1500a to 1500c are retractable towards the front of the device to accommodate the sheets S. Each sheet S is fed one by one from each storage compartment 1500a to 1500c by a separation belt and transport rollers, and then transported to the print module 2000. Note that the storage compartments 1500a to 1500c are not limited to three; there may be one, two, or four or more. The print module 2000, which functions as the image forming unit, comprises a pre-image registration correction unit (not shown), a print belt unit 2010, and a recording unit 2020. The sheet S, transported from the paper feed module 1000, is corrected for tilt and position by the pre-image registration correction unit before being transported to the print belt unit 2010. The recording unit 2020 is positioned op