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US-20260126743-A1 - TEMPERATURE CONTROL DEVICE AND IMAGE FORMING APPARATUS INCLUDING TEMPERATURE CONTROL DEVICE

US20260126743A1US 20260126743 A1US20260126743 A1US 20260126743A1US-20260126743-A1

Abstract

A temperature control device controls power supplied to a heater based on a temperature estimate value estimated over time so that a temperature control target to which heat propagates from the heater of the fixing unit reaches a preset target temperature. The temperature control device includes a temperature sensor, first and second storage circuits, a temperature difference detection circuit, and a target temperature correction circuit. The temperature sensor detects a temperature of the heater. The first storage circuit stores the temperature estimate value. The second storage circuit stores a sensor temperature. The temperature difference detection circuit calculates an actual temperature rise amount from a temperature difference between the temperature estimate value and the temperature of the heater from the respective storage circuits. The temperature correction circuit performs control such that a target temperature is lowered in accordance with the actual temperature rise amount.

Inventors

  • Takeshi Kojima

Assignees

  • TOSHIBA TEC KABUSHIKI KAISHA

Dates

Publication Date
20260507
Application Date
20251222
Priority Date
20230601

Claims (16)

  1. 1 - 14 . (canceled)
  2. 15 . A temperature controller configured to control power supplied to a heater based on a temperature estimate value estimated over time so that a temperature control target, to which heat propagates from the heater of a fixer, reaches a preset target temperature, the temperature controller comprising: a temperature sensor configured to detect a temperature of the heater; a first storage circuit configured to store the temperature estimate value acquired at a random time and obtained by weighted average control; a second storage circuit configured to store a sensor temperature detected by the temperature sensor; a temperature difference detection circuit configured to calculate an actual temperature rise amount from a temperature difference between the temperature estimate value read from the first storage circuit and the temperature of the heater read from the second storage circuit; and a target temperature correction circuit configured to lower a target temperature in accordance with the actual temperature rise amount.
  3. 16 . The temperature controller of claim 15 , wherein the target temperature correction circuit has a plurality of control correction temperatures correlated to the actual temperature rise amount calculated from differences between temperatures of (i) a normal temperature control target during a rise of the temperature of the heater and (ii) a present actual temperature of the temperature control target, and the target temperature correction circuit is configured to generate a correction target temperature corrected by subtracting the control correction temperature in accordance with the actual temperature rise amount from a presently set target temperature.
  4. 17 . The temperature controller of claim 15 , wherein the temperature difference detection circuit has a temperature characteristic in which a first temperature rise amount, the first temperature rise amount calculated from a difference between the temperature estimate value and the sensor temperature, and the actual temperature rise amount are associated with each other, and is configured to estimate the actual temperature rise amount from the temperature characteristic based on the acquired temperature estimate value and the sensor temperature.
  5. 18 . The temperature controller of claim 15 , further comprising a temperature estimation circuit configured to estimate the temperature estimate value of the temperature control target from thermal capacity of the heater and thermal resistance of the fixer based on electrification to the heater.
  6. 19 . An image forming apparatus comprising the temperature controller of claim 15 .
  7. 20 . The image forming apparatus of claim 19 , wherein the image forming apparatus is a multi-function peripheral.
  8. 21 . The temperature controller of claim 15 , wherein the temperature sensor includes a plurality of temperature sensors, each of the plurality of temperature sensors contacting a different region of the heater.
  9. 22 . A method of controlling power supplied to a heater based on a temperature estimate value estimated over time so that a temperature control target, to which heat propagates from the heater of a fixer, reaches a preset target temperature, the method comprising: storing, by a first storage circuit, the temperature estimate value acquired at a random time; storing, by a second storage circuit, a temperature of the heater detected by a temperature sensor; calculating an actual temperature rise amount from a temperature difference between the temperature estimate value read from the first storage circuit and the temperature of the heater read from the second storage circuit; calculating a plurality of control correction temperatures correlated to the actual temperature rise amount from differences between temperatures of (i) a normal temperature control target during a rise of the temperature of the heater and (ii) a present actual temperature of the temperature control target; and lowering a target temperature by generating a correction target temperature corrected by subtracting the control correction temperature in accordance with the actual temperature rise amount from a presently set target temperature.
  10. 23 . The method of claim 22 , wherein calculating the actual temperature rise amount includes: estimating the actual temperature rise amount from a temperature characteristic based on the acquired temperature estimate value and the sensor temperature, wherein in the temperature characteristic a first temperature rise amount, the first temperature rise amount being calculated from a difference between the temperature estimate value and the sensor temperature, and the actual temperature rise amount are associated with each other.
  11. 24 . The method of claim 22 , wherein the sensor temperature is a first sensor temperature and the temperature sensor is a first temperature sensor of a plurality of temperature sensors, each of the plurality of temperature sensors contacting a different region of the heater, further comprising: storing, by the second storage circuit, a second sensor temperature detected by a second temperature sensor of the plurality of temperature sensors.
  12. 25 . The method of claim 22 , further comprising: estimating the temperature estimate value of the temperature control target by weighted average control.
  13. 26 . The method of claim 22 , further comprising: estimating the temperature estimate value of the temperature control target from a thermal capacity of the heater and thermal resistance of the fixer based on electrification to the heater.
  14. 27 . A method of controlling power supplied to a heater based on a temperature estimate value estimated over time so that a temperature control target, to which heat propagates from the heater of a fixer, reaches a preset target temperature, the method comprising: estimating the temperature estimate value of the temperature control target from a thermal capacity of the heater and thermal resistance of the fixer based on electrification to the heater; storing, by a first storage circuit, the temperature estimate value acquired at a random time; storing, by a second storage circuit, a temperature of the heater detected by a temperature sensor; calculating an actual temperature rise amount from a temperature difference between the temperature estimate value read from the first storage circuit and the temperature of the heater read from the second storage circuit; and lowering a target temperature by in accordance with the actual temperature rise amount.
  15. 28 . The method of claim 27 , wherein calculating the actual temperature rise amount includes: estimating the actual temperature rise amount from a temperature characteristic based on the acquired temperature estimate value and the sensor temperature, wherein in the temperature characteristic a first temperature rise amount, the first temperature rise amount being calculated from a difference between the temperature estimate value and the sensor temperature, and the actual temperature rise amount are associated with each other.
  16. 29 . The method of claim 27 , wherein the sensor temperature is a first sensor temperature and the temperature sensor is a first temperature sensor of a plurality of temperature sensors, each of the plurality of temperature sensors contacting a different region of the heater, further comprising: storing, by the second storage circuit, a second sensor temperature detected by a second temperature sensor of the plurality of temperature sensors.

Description

CROSS-REFERENCE TO RELATED APPLICATION This application is based upon and claims the benefit of priority from Japanese Patent Application No. 2023-090901, filed on Jun. 1, 2023, the entire contents of which are incorporated herein by reference. FIELD Embodiments described herein relate generally to a temperature control device and an image forming apparatus including the temperature control device. BACKGROUND An image forming apparatus placed on a workplace or the like includes a fixing unit that fixes a toner image to a recording medium to which the toner image was transferred by applying heat and pressure to the recording medium. The fixing unit includes a temperature sensor that detects a temperature of the surface of a heat roller (fixing member). The fixing unit performs control so that a surface temperature of the heat roller reaches a target value by increasing or decreasing an amount of power supplied to a heat member (a lamp, an IH heater, or the like) based on a detection signal of the temperature sensor. As recognized by the inventor of the present application, when foreign matters are inserted between the temperature sensor and the heat roller or dirt of toner is adhered to the temperature sensor, the fixing unit may not detect an accurate temperature even if the temperature sensor itself is normal. When the temperature sensor cannot detect an accurate temperature, a difference may occur between a temperature of the heat roller and a temperature detected by the temperature sensor, an inappropriate target value is set, and the temperature is controlled. As a result, the temperature of the fixing unit increases, which causes hot offset and a service call, and thus the image forming apparatus cannot operate temporarily in some situations. DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram conceptually illustrating an overall configuration example of an image forming apparatus according to at least one embodiment; FIG. 2 is a block diagram illustrating a configuration example of a temperature control device; FIG. 3 is a diagram illustrating a configuration example of a heater unit in a fixing unit; FIG. 4 is a flowchart illustrating a weighted average with estimate of temperature (WAE) control; FIG. 5 is a diagram illustrating an actually measured temperature and a temperature of a temperature estimate value when a clearance is left at a center; FIG. 6 is a diagram illustrating an actually measured temperature and a temperature of a temperature estimate value when a clearance is left in a side; FIG. 7 is a diagram illustrating a temperature characteristic of a temperature estimate value WAE at the center, an actual temperature of the heat roller, and a sensor temperature; FIG. 8 is a diagram illustrating a temperature characteristic of a temperature estimate value WAE at the side, actual temperature of the heat roller, and a sensor temperature; FIG. 9 is a diagram illustrating a correlation of a temperature rise amount based on the temperature characteristic at the center; FIG. 10 is a diagram illustrating a correlation of a temperature rise amount based on the temperature characteristic at the side; FIG. 11 is a diagram illustrating setting of a control correction temperature with respect to an actual temperature rise amount of the heat roller; FIG. 12 is a diagram illustrating a correlation among an actual temperature rise amount of the heat roller, a first temperature rise amount center, and a control correction temperature; FIG. 13 is a diagram illustrating a correlation among the actual temperature rise amount of the heat roller, a first temperature rise amount side, and the control correction temperature; FIG. 14 is a flowchart illustrating temperature control of the fixing unit; FIG. 15 is a diagram illustrating a second configuration example of the fixing unit; FIG. 16 is a diagram illustrating a configuration example of the heater unit in the fixing unit of the second configuration example; FIG. 17 is a diagram illustrating a third configuration example of the fixing unit; FIG. 18 is a diagram illustrating a configuration example of the heater unit in the fixing unit of the third configuration example; FIG. 19 is a diagram illustrating a fourth configuration example of the fixing unit; FIG. 20 is a diagram illustrating a configuration example of the heater unit in the fixing unit of the fourth configuration example; FIG. 21 is a diagram illustrating a fifth configuration example of the fixing unit; and FIG. 22 is a diagram illustrating a configuration example of the heater unit in the fixing unit of the fifth configuration example. DETAILED DESCRIPTION In general, according to at least one embodiment, provided are a temperature control device (temperature controller) and an image forming apparatus including the temperature control device that determines a failure of a detected temperature from a correlation between a calculated temperature estimate value and a sensor temperature and performs t