JP2001100590A - Temperature controller for fixing device and controlling method for the controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a temperature controller for a fixing device which safely and surely detects abnormality of temperature detection of the fixing device. SOLUTION: If a digital conversion value outputted from an A/D conversion means for abnormality detection is abnormal as room temperature after the resistance of a voltage dividing resistor is switched by a voltage dividing resistance switching means so that a temperature/voltage conversion signal for abnormality detection having temperature/voltage characteristics suitable for temperature detection of the room temperature or its neighborhood may be obtained, abnormality of temperature detection due to the thermistor is decided to perform processing coping with abnormality.

Description

【発明の詳細な説明】DETAILED DESCRIPTION OF THE INVENTION

【０００１】[0001]

【発明の属する技術分野】本発明は、定着器を加熱する
ヒータへの供給電力を制御することにより前記定着器の
温度を制御する、定着器の温度制御装置及びその制御方
法に関する。[0001] 1. Field of the Invention [0002] The present invention relates to a fixing device temperature control device and a control method for controlling the temperature of the fixing device by controlling the power supplied to a heater for heating the fixing device.

【０００２】[0002]

【従来の技術】複写機、ファクシミリ装置、プリンタ装
置等の画像記録装置に使用される定着器は、記録紙に転
写されたトナー像をその記録紙に熱定着させるために所
定の高温（定着温度）である必要がある。そのため、従
来の定着器の温度制御装置は、定着器の近傍にサーミス
タを配置し、そのサーミスタの定着器の温度に応じた抵
抗値の変化を電圧の変化に変換して検出することによ
り、定着器の温度を検出し、その検出される温度が前記
定着温度になるように、前記定着器を加熱するヒータに
供給する電力量を制御している。2. Description of the Related Art A fixing device used in an image recording apparatus such as a copying machine, a facsimile machine, a printer, or the like, has a predetermined high temperature (fixing temperature) for thermally fixing a toner image transferred to a recording sheet onto the recording sheet. ). For this reason, the conventional temperature control device for a fixing device arranges a thermistor in the vicinity of the fixing device, and converts a change in resistance value of the thermistor according to the temperature of the fixing device into a change in voltage to detect the change. The temperature of the fixing device is detected, and the amount of electric power supplied to the heater for heating the fixing device is controlled so that the detected temperature becomes the fixing temperature.

【０００３】しかし、サーミスタの断線やコネクタ抜け
等により定着器の実際の温度を温度制御装置が正しく検
出できなくなると、定着器の温度を定着温度に保持する
とができなくなるばかりでなく、前記定着器の温度が実
際には高くなっているのに低いものと誤検出されて前記
ヒータに電力が供給され続けてしまい、前記定着器が異
常な高温となって火災発生の危険が生じうる。However, if the temperature control device cannot correctly detect the actual temperature of the fixing device due to disconnection of the thermistor, disconnection of the connector, etc., not only can the temperature of the fixing device not be maintained at the fixing temperature, but also the fixing device cannot be maintained. Although the temperature is actually high, it is erroneously detected that the temperature is low, and the power is continuously supplied to the heater, so that the fixing unit becomes abnormally high and there is a danger of fire.

【０００４】したがって、サーミスタが正常に機能して
いるかを知ることは、定着器の温度制御装置にとっては
トナー像の確実な定着のためのみならず、装置の安全性
の確保のためにも非常に重要である。Therefore, knowing whether the thermistor is functioning properly is very important not only for the fixing of the toner image but also for the security of the device for the temperature control device of the fixing device. is important.

【０００５】サーミスタを温度検出センサとして使用す
る場合、温度変化により抵抗値が変化しない抵抗器を直
列接続して合成抵抗を構成し、その合成抵抗に安定な基
準電圧を印可してその合成抵抗の接続点から電圧を、温
度／電圧変換信号として得るようにしている。When a thermistor is used as a temperature detection sensor, a resistor whose resistance value does not change due to a temperature change is connected in series to form a combined resistor, and a stable reference voltage is applied to the combined resistor, and the combined resistor is connected to the resistor. A voltage is obtained from the connection point as a temperature / voltage conversion signal.

【０００６】しかし、サーミスタは、低温から比較的高
温までの温度検出な可能な温度検出素子ではあるが、温
度変化に対する抵抗値の変化が非線形であるため直列接
続される分圧抵抗の抵抗値に応じて、温度変化に対する
温度／電圧変換信号の変化量が大きな温度範囲、すなわ
ち、温度を精度よく検出できる範囲が遷移する。However, the thermistor is a temperature detecting element capable of detecting a temperature from a low temperature to a relatively high temperature. However, since the change in the resistance value with respect to the temperature change is non-linear, the resistance value of the voltage-dividing resistor connected in series is limited. Accordingly, the temperature range in which the amount of change of the temperature / voltage conversion signal with respect to the temperature change is large, that is, the range in which the temperature can be detected with high accuracy is changed.

【０００７】したがって、サーミスタを、例えば１８０
℃度等の比較的高温な定着温度の制御のために使用する
場合には、分圧抵抗の抵抗値は、定着温度付近の温度を
精度よく検出できる値に設定されることになる。Therefore, a thermistor, for example, 180
When used for controlling a relatively high fixing temperature such as degrees Celsius, the resistance value of the voltage dividing resistor is set to a value that can accurately detect a temperature near the fixing temperature.

【０００８】一方、サーミスタにより、断線やコネクタ
抜け等の温度検出の異常を精度よく検知するためには、
定着器が取り得る温度範囲と、断線やコネクタ抜け等に
よる見かけ上検出される異常に低い温度とを精度よく区
別して検出できる必要がある。On the other hand, in order to accurately detect an abnormality in temperature detection such as disconnection or disconnection of a connector by a thermistor,
It is necessary to be able to accurately distinguish and detect a temperature range that can be taken by the fixing device and an abnormally low temperature that is apparently detected due to disconnection or disconnection of a connector.

【０００９】定着器のとりうる温度範囲は、室温（例え
ば１０℃〜３０℃）から定着温度付近までであるが、従
来、前記サーミスタは、定着温度付近の温度を精度よく
検出できる値に分圧抵抗の抵抗値が設定されていたた
め、室温付近の温度の検出精度は低く、断線やコネクタ
抜け等による見かけ上検出される異常に低い温度と室温
とを精度よく区別するのが難しかった。The temperature range that the fixing device can take is from room temperature (for example, 10 ° C. to 30 ° C.) to the vicinity of the fixing temperature. Conventionally, the thermistor has a partial pressure that can accurately detect the temperature around the fixing temperature. Since the resistance value of the resistor is set, the detection accuracy of the temperature near the room temperature is low, and it is difficult to accurately distinguish the abnormally low temperature apparently detected due to disconnection, disconnection of the connector, etc. from the room temperature.

【００１０】[0010]

【発明が解決しようとする課題】そのため、定着温度付
近の温度を精度よく検出できる値に分圧抵抗の抵抗値が
設定されたサーミスタにより、室温からヒータを加熱す
るのに先だって、温度検出の異常の有無を検知しようと
した場合に、実際には室温の範囲内にある定着器の温度
を、誤って断線やコネクタ抜け等に相当する異常に低い
温度と誤検出してしまって、故障でもないのにヒータ加
熱を停止して装置動作を止めてしまうという問題点があ
った。Therefore, prior to heating the heater from room temperature, a thermistor in which the resistance value of the voltage dividing resistor is set to a value at which the temperature near the fixing temperature can be detected accurately can be detected abnormally. If you try to detect the presence or absence of the fuser, the temperature of the fixing unit actually within the room temperature range is erroneously detected as an abnormally low temperature corresponding to disconnection, disconnection of the connector, etc. However, there is a problem that the operation of the apparatus is stopped by stopping the heating of the heater.

【００１１】そのような問題を解決する従来技術として
は、特開平６−８３２２０号公報記載の「加熱定着装置
及び画像形成装置」がある。その従来技術では、定着ヒ
ーター（加熱体）を一定時間かつ暴走にならない領域で
加熱することで、室温よりは高温の比較的精度よく定着
器の温度を検出できる温度領域で、ヒータの断線検知や
温度検知素子の故障検知を行うようにするしている。As a conventional technique for solving such a problem, there is a "heat fixing device and an image forming apparatus" described in JP-A-6-83220. In the prior art, the fixing heater (heating body) is heated for a certain period of time and in a region where runaway does not occur, so that the temperature of the fixing device can be relatively accurately detected at a temperature higher than room temperature. The failure detection of the temperature detection element is performed.

【００１２】しかしながら、この方式の場合一定時間加
熱するので、一定時間が経過する前に装置電源ＯＦＦ等
の強制終了と電源再投入が繰り返し行われた場合、一定
時間の加熱してから温度検知素子系の不具合（コネクタ
が抜け・断線）を検知する制御手順が繰り返し初期化さ
れて、一定時間の加熱が繰り返し行われてしまい、それ
によりヒータが過熱し結果として装置を破壊してしまう
おそれがある問題がある。However, in this method, since the heating is performed for a certain period of time, if forcible termination such as turning off the power of the apparatus and re-turning on the power are repeated before the predetermined period of time elapses, the temperature detecting element is heated for a certain period of time. A control procedure for detecting a system failure (connector disconnection / disconnection) is repeatedly initialized, and heating for a certain period of time is repeatedly performed. As a result, the heater may be overheated and the apparatus may be destroyed as a result. There's a problem.

【００１３】本発明は係る事情に鑑みてなされたもので
あり、定着器の温度検出の異常の有無を安全かつ確実に
検出することができる定着器の温度制御装置及びその制
御方法を提供することを目的とする。SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and provides a fixing device temperature control device and a control method thereof capable of safely and reliably detecting the presence or absence of an abnormality in the temperature detection of the fixing device. With the goal.

【００１４】[0014]

【課題を解決するための手段】請求項１に記載の定着器
の温度制御装置は、定着器を加熱するヒータへの供給電
力を制御することにより前記定着器の温度を定着温度に
制御する定着器の温度制御装置において、前記定着器の
温度変化に応じてその抵抗値が変化するサーミスタと、
前記サーミスタに直列接続され抵抗値が可変に構成され
た分圧抵抗器と、前記サーミスタと前記分圧抵抗器とを
直列接続して構成される合成抵抗の両端に所定の電圧を
印加してその接続点から得られる温度／電圧変換信号
が、前記定着温度付近の温度を精度よく検出できる温度
／電圧特性の定着制御用温度／電圧変換信号、または、
室温付近の温度を精度よく検出できる温度／電圧特性の
異常検出用温度／電圧変換信号になるよう前記分圧抵抗
器の抵抗値を切り換える分圧抵抗値切換手段と、前記定
着制御用温度／電圧変換信号をアナログ／デジタル変換
する定着制御用Ａ／Ｄ変換手段と、異常検出用温度／電
圧変換信号をアナログ／デジタル変換する異常検出用Ａ
／Ｄ変換手段と、前記分圧抵抗値切換手段により前記定
着温度付近の温度検出に適した温度／電圧特性の定着制
御用温度／電圧変換信号になるよう前記分圧抵抗器の抵
抗値を切り換えた上で前記定着制御用Ａ／Ｄ変換手段か
ら出力されるデジタル変換値が、前記定着温度に対応し
た所定の値になるよう前記定着器を加熱するヒータへの
供給電力を制御して前記定着器の温度を前記定着温度に
制御する定着温度制御手段と、前記分圧抵抗値切換手段
により室温付近の温度検出に適した温度／電圧特性の異
常検出用温度／電圧変換信号になるよう前記分圧抵抗器
の抵抗値を切り換えた上で前記異常検出用Ａ／Ｄ変換手
段から出力されるデジタル変換値が室温としては異常な
値である場合に、前記サーミスタによる温度検出の異常
と判定し異常対応処理を行う温度検出異常検出手段とを
備えたことを特徴とする。According to a first aspect of the present invention, there is provided a fixing device temperature control apparatus for controlling the temperature of the fixing unit to a fixing temperature by controlling power supplied to a heater for heating the fixing unit. A temperature controller for the fixing device, wherein a resistance value of the thermistor changes according to a temperature change of the fixing device;
A voltage dividing resistor that is connected in series to the thermistor and has a variable resistance value, and a predetermined voltage is applied to both ends of a combined resistor formed by connecting the thermistor and the voltage dividing resistor in series. The temperature / voltage conversion signal obtained from the connection point is a temperature / voltage conversion signal for fixing control having a temperature / voltage characteristic capable of accurately detecting a temperature near the fixing temperature, or
Voltage-dividing resistance value switching means for switching the resistance value of the voltage-dividing resistor so as to become a temperature / voltage conversion signal for abnormality detection of temperature / voltage characteristics capable of accurately detecting a temperature near room temperature; and the fixing control temperature / voltage. A / D conversion means for fixing control for analog / digital conversion of a conversion signal, and A for abnormality detection for analog / digital conversion of a temperature / voltage conversion signal for abnormality detection
The resistance value of the voltage-dividing resistor is switched by the / D conversion means and the voltage-dividing resistance value switching means so that the temperature / voltage conversion signal for fixing control has a temperature / voltage characteristic suitable for detecting the temperature near the fixing temperature. The power supply to the heater for heating the fixing unit is controlled so that the digital conversion value output from the fixing control A / D conversion unit becomes a predetermined value corresponding to the fixing temperature. A fixing temperature control means for controlling the temperature of the fixing device to the fixing temperature; and a temperature / voltage conversion signal for abnormality detection of temperature / voltage characteristics suitable for temperature detection near room temperature by the voltage dividing resistance value switching means. If the digital conversion value output from the abnormality detection A / D conversion means after switching the resistance value of the piezoresistor is an abnormal value for room temperature, it is determined that the temperature detection by the thermistor is abnormal and abnormal. Correspondence Characterized by comprising a temperature detecting abnormality detecting means for performing management.

【００１５】請求項２に記載の定着器の温度制御装置の
制御方法は、定着器を加熱するヒータへの供給電力を制
御することにより前記定着器の温度を定着温度に制御す
る定着器の温度制御装置の制御方法において、前記定着
器の温度変化に応じてその抵抗値が変化するサーミスタ
と、前記サーミスタに直列接続され抵抗値が可変に構成
された分圧抵抗器と、前記サーミスタと前記分圧抵抗器
とを直列接続して構成される合成抵抗の両端に所定の電
圧を印加してその接続点から得られる温度／電圧変換信
号が、前記定着温度付近の温度を精度よく検出できる温
度／電圧特性の定着制御用温度／電圧変換信号、また
は、室温付近の温度を精度よく検出できる温度／電圧特
性の異常検出用温度／電圧変換信号になるよう前記分圧
抵抗器の抵抗値を切り換える分圧抵抗値切換手段と、前
記定着制御用温度／電圧変換信号をアナログ／デジタル
変換する定着制御用Ａ／Ｄ変換手段と、異常検出用温度
／電圧変換信号をアナログ／デジタル変換する異常検出
用Ａ／Ｄ変換手段とを有し、前記分圧抵抗値切換手段に
より前記定着温度付近の温度検出に適した温度／電圧特
性の定着制御用温度／電圧変換信号になるよう前記分圧
抵抗器の抵抗値を切り換えた上で前記定着制御用Ａ／Ｄ
変換手段から出力されるデジタル変換値が、前記定着温
度に対応した所定の値になるよう前記定着器を加熱する
ヒータへの供給電力を制御して前記定着器の温度を前記
定着温度に制御する一方、前記分圧抵抗値切換手段によ
り室温付近の温度検出に適した温度／電圧特性の異常検
出用温度／電圧変換信号になるよう前記分圧抵抗器の抵
抗値を切り換えた上で前記異常検出用Ａ／Ｄ変換手段か
ら出力されるデジタル変換値が室温としては異常な値で
ある場合に、前記サーミスタによる温度検出の異常と判
定し異常対応処理を行うことを特徴とする。According to a second aspect of the present invention, there is provided a method for controlling a temperature of a fixing device, wherein the temperature of the fixing device is controlled to a fixing temperature by controlling power supplied to a heater for heating the fixing device. In the control method of the control device, a thermistor whose resistance value changes according to a temperature change of the fixing device; a voltage-dividing resistor connected in series to the thermistor and having a variable resistance value; A temperature / voltage conversion signal obtained by applying a predetermined voltage to both ends of a combined resistor configured by connecting a piezoresistor in series to obtain a temperature / voltage conversion signal that can accurately detect a temperature near the fixing temperature. The resistance value of the voltage-dividing resistor is cut off so as to become a fixing / temperature conversion signal for fixing control of a voltage characteristic or a temperature / voltage conversion signal for abnormality detection of a temperature / voltage characteristic capable of accurately detecting a temperature near room temperature. A voltage dividing resistance switching means for changing, a fixing control A / D converting means for analog / digital conversion of the fixing control temperature / voltage conversion signal, and an abnormality detection for analog / digital conversion of the abnormality detecting temperature / voltage conversion signal. A / D conversion means, and the voltage-dividing resistor so that the voltage-dividing resistance switching means becomes a fixing control temperature / voltage conversion signal having a temperature / voltage characteristic suitable for detecting a temperature near the fixing temperature. A / D for fixing control after switching the resistance value of
The temperature of the fixing unit is controlled to the fixing temperature by controlling power supplied to a heater for heating the fixing unit so that the digital conversion value output from the converting unit becomes a predetermined value corresponding to the fixing temperature. On the other hand, the resistance value of the voltage-dividing resistor is switched by the voltage-dividing resistance value switching means so as to provide a temperature / voltage conversion signal for abnormality detection of temperature / voltage characteristics suitable for temperature detection around room temperature, and then the abnormality detection is performed. When the digital conversion value output from the A / D converter for use is an abnormal value at room temperature, it is determined that the temperature detection by the thermistor is abnormal, and an abnormality handling process is performed.

【００１６】請求項３に記載の定着器の温度制御装置
は、定着器を加熱するヒータへの供給電力を制御するこ
とにより前記定着器の温度を定着温度に制御する定着器
の温度制御装置において、前記定着器の温度変化に応じ
てその抵抗値が変化するサーミスタと、前記サーミスタ
に直列接続され抵抗値が可変に構成された分圧抵抗器
と、前記サーミスタと前記分圧抵抗器とを直列接続して
構成される合成抵抗の両端に所定の電圧を印加してその
接続点から得られる温度／電圧変換信号が、前記定着温
度付近の温度を精度よく検出できる温度／電圧特性の定
着制御用温度／電圧変換信号、または、室温付近の温度
を精度よく検出できる温度／電圧特性の異常検出用温度
／電圧変換信号になるよう前記分圧抵抗器の抵抗値を切
り換える分圧抵抗値切換手段と、前記定着制御用温度／
電圧変換信号及び前記異常検出用温度／電圧変換信号を
時分割で切り換えてアナログ／デジタル変換するＡ／Ｄ
変換手段と、前記分圧抵抗値切換手段により前記定着温
度付近の温度検出に適した温度／電圧特性の定着制御用
温度／電圧変換信号になるよう前記分圧抵抗器の抵抗値
を切り換えた上で前記Ａ／Ｄ変換手段から出力されるデ
ジタル変換値が、前記定着温度に対応した所定の値にな
るよう前記定着器を加熱するヒータへの供給電力を制御
して前記定着器の温度を前記定着温度に制御する定着温
度制御手段と、前記分圧抵抗値切換手段により室温付近
の温度検出に適した温度／電圧特性の異常検出用温度／
電圧変換信号になるよう前記分圧抵抗器の抵抗値を切り
換えた上で前記Ａ／Ｄ変換手段から出力されるデジタル
変換値が室温としては異常な値である場合に、前記サー
ミスタによる温度検出の異常と判定し異常対応処理を行
う温度検出異常検出手段とを備えたことを特徴とする。According to a third aspect of the present invention, there is provided a temperature control device for a fixing device, wherein the temperature of the fixing device is controlled to a fixing temperature by controlling power supplied to a heater for heating the fixing device. A thermistor whose resistance value changes according to a temperature change of the fixing device, a voltage-dividing resistor connected in series to the thermistor and having a variable resistance value, and the thermistor and the voltage-dividing resistor connected in series. A temperature / voltage conversion signal obtained by applying a predetermined voltage to both ends of a combined resistor formed by connection and obtained from the connection point is used for fixing control of temperature / voltage characteristics capable of accurately detecting a temperature near the fixing temperature. Switching the resistance value of the voltage-dividing resistor so that it becomes a temperature / voltage conversion signal or a temperature / voltage conversion signal for abnormality detection of temperature / voltage characteristics that can accurately detect a temperature near room temperature. Means, the fixing control temperature /
A / D for performing analog / digital conversion by switching the voltage conversion signal and the abnormality detection temperature / voltage conversion signal in a time division manner
The resistance value of the voltage-dividing resistor is switched by the conversion means and the voltage-dividing resistance value switching means so that the temperature / voltage conversion signal for fixing control has a temperature / voltage characteristic suitable for detecting the temperature near the fixing temperature. And controlling the power supplied to the heater for heating the fixing unit so that the digital conversion value output from the A / D conversion unit becomes a predetermined value corresponding to the fixing temperature. Fixing temperature control means for controlling to a fixing temperature, and temperature / temperature for abnormality detection of voltage / voltage characteristics suitable for detecting a temperature near room temperature by the voltage dividing resistance value switching means.
After the resistance value of the voltage dividing resistor is switched so as to become a voltage conversion signal, if the digital conversion value output from the A / D conversion means is an abnormal value as room temperature, the temperature detection by the thermistor is performed. A temperature detecting abnormality detecting means for performing an abnormality responding process by judging an abnormality.

【００１７】請求項４に記載の定着器の温度制御装置の
制御方法は、定着器を加熱するヒータへの供給電力を制
御することにより前記定着器の温度を定着温度に制御す
る定着器の温度制御装置の制御方法において、前記定着
器の温度変化に応じてその抵抗値が変化するサーミスタ
と、前記サーミスタに直列接続され抵抗値が可変に構成
された分圧抵抗器と、前記サーミスタと前記分圧抵抗器
とを直列接続して構成される合成抵抗の両端に所定の電
圧を印加してその接続点から得られる温度／電圧変換信
号が、前記定着温度付近の温度を精度よく検出できる温
度／電圧特性の定着制御用温度／電圧変換信号、また
は、室温付近の温度を精度よく検出できる温度／電圧特
性の異常検出用温度／電圧変換信号になるよう前記分圧
抵抗器の抵抗値を切り換える分圧抵抗値切換手段と、前
記定着制御用温度／電圧変換信号及び前記異常検出用温
度／電圧変換信号を時分割で切り換えてアナログ／デジ
タル変換するＡ／Ｄ変換手段とを有し、前記分圧抵抗値
切換手段により前記定着温度付近の温度検出に適した温
度／電圧特性の定着制御用温度／電圧変換信号になるよ
う前記分圧抵抗器の抵抗値を切り換えた上で前記Ａ／Ｄ
変換手段から出力されるデジタル変換値が、前記定着温
度に対応した所定の値になるよう前記定着器を加熱する
ヒータへの供給電力を制御して前記定着器の温度を前記
定着温度に制御する一方、前記分圧抵抗値切換手段によ
り室温付近の温度検出に適した温度／電圧特性の異常検
出用温度／電圧変換信号になるよう前記分圧抵抗器の抵
抗値を切り換えた上で前記Ａ／Ｄ変換手段から出力され
るデジタル変換値が室温としては異常な値である場合
に、前記サーミスタによる温度検出の異常と判定し異常
対応処理を行うことを特徴とする。According to a fourth aspect of the present invention, there is provided a method of controlling a temperature of a fixing device, wherein the temperature of the fixing device is controlled to a fixing temperature by controlling power supplied to a heater for heating the fixing device. In the control method of the control device, a thermistor whose resistance value changes according to a temperature change of the fixing device; a voltage-dividing resistor connected in series to the thermistor and having a variable resistance value; A temperature / voltage conversion signal obtained by applying a predetermined voltage to both ends of a combined resistor configured by connecting a piezoresistor in series to obtain a temperature / voltage conversion signal that can accurately detect a temperature near the fixing temperature. The resistance value of the voltage-dividing resistor is cut off so as to become a fixing / temperature conversion signal for fixing control of a voltage characteristic or a temperature / voltage conversion signal for abnormality detection of a temperature / voltage characteristic capable of accurately detecting a temperature near room temperature. Voltage dividing resistance value switching means for changing the temperature / voltage conversion signal for fixing control and the temperature / voltage conversion signal for abnormality detection and performing A / D conversion means for analog / digital conversion by time division. The resistance value of the voltage-dividing resistor is switched by a voltage-dividing resistance value switching means so that the temperature / voltage conversion signal for fixing control has a temperature / voltage characteristic suitable for detecting the temperature near the fixing temperature, and then the A / D is switched.
The temperature of the fixing unit is controlled to the fixing temperature by controlling power supplied to a heater for heating the fixing unit so that the digital conversion value output from the converting unit becomes a predetermined value corresponding to the fixing temperature. On the other hand, after the resistance value of the voltage-dividing resistor is switched by the voltage-dividing resistance value switching means so as to obtain a temperature / voltage conversion signal for abnormality detection of temperature / voltage characteristics suitable for temperature detection around room temperature, When the digital conversion value output from the D conversion means is an abnormal value at room temperature, it is determined that the temperature detection by the thermistor is abnormal, and an abnormality handling process is performed.

【００１８】請求項５に記載の定着器の温度制御装置
は、請求項１に記載の定着器の温度制御装置において、
前記温度検出異常検出手段は、前記分圧抵抗値切換手段
により前記定着温度付近の温度検出に適した温度／電圧
特性の定着制御用温度／電圧変換信号になるよう前記分
圧抵抗器の抵抗値を切り換えた上で前記定着制御用Ａ／
Ｄ変換手段から出力されるデジタル変換値が、所定の下
限値以下の場合にのみ、前記分圧抵抗値切換手段により
室温付近の温度検出に適した温度／電圧特性の異常検出
用温度／電圧変換信号になるよう前記分圧抵抗器の抵抗
値を切り換えて、前記異常検出用Ａ／Ｄ変換手段から出
力されるデジタル変換値が室温としては異常な値である
場合に、温度検出異常と判定し異常対応処理を行うこと
を特徴とする。According to a fifth aspect of the present invention, there is provided a temperature control device for a fixing device according to the first aspect.
The temperature detection abnormality detecting means includes a resistance value of the voltage-dividing resistor which becomes a temperature / voltage conversion signal for fixing control having a temperature / voltage characteristic suitable for temperature detection near the fixing temperature by the voltage-dividing resistance value switching means. And then the fixing control A /
Only when the digital conversion value output from the D conversion means is equal to or less than a predetermined lower limit value, is the temperature / voltage conversion for abnormality detection of temperature / voltage characteristics suitable for temperature detection near room temperature by the voltage dividing resistance value switching means. The resistance value of the voltage dividing resistor is switched so as to become a signal, and when the digital conversion value output from the A / D converter for abnormality detection is an abnormal value as room temperature, it is determined that the temperature detection is abnormal. An abnormality handling process is performed.

【００１９】請求項６に記載の定着器の温度制御装置の
制御方法は、請求項２に記載の定着器の温度制御装置の
制御方法において、前記前記分圧抵抗値切換手段により
前記定着温度付近の温度検出に適した温度／電圧特性の
定着制御用温度／電圧変換信号になるよう前記分圧抵抗
器の抵抗値を切り換えた上で前記定着制御用Ａ／Ｄ変換
手段から出力されるデジタル変換値が、所定の下限値以
下の場合にのみ、前記分圧抵抗値切換手段により室温付
近の温度検出に適した温度／電圧特性の異常検出用温度
／電圧変換信号になるよう前記分圧抵抗器の抵抗値を切
り換えて、前記異常検出用Ａ／Ｄ変換手段から出力され
るデジタル変換値が室温としては異常な値である場合
に、温度検出異常と判定し異常対応処理を行うことを特
徴とする。According to a sixth aspect of the present invention, there is provided a method of controlling a temperature control device for a fixing unit according to the second aspect of the present invention. The digital conversion output from the fixing control A / D conversion means after switching the resistance value of the voltage dividing resistor so as to obtain a fixing control temperature / voltage conversion signal having a temperature / voltage characteristic suitable for temperature detection Only when the value is equal to or less than a predetermined lower limit value, the voltage-dividing resistor is changed to a temperature / voltage conversion signal for abnormality detection of temperature / voltage characteristics suitable for temperature detection near room temperature by the voltage-dividing resistance switching means. And when the digital conversion value output from the abnormality detection A / D conversion means is an abnormal value as room temperature, it is determined that the temperature is abnormal and an abnormality handling process is performed. I do.

【００２０】請求項７に記載の定着器の温度制御装置
は、請求項３に記載の定着器の温度制御装置において、
前記温度検出異常検出手段は、前記分圧抵抗値切換手段
により前記定着温度付近の温度検出に適した温度／電圧
特性の定着制御用温度／電圧変換信号になるよう前記分
圧抵抗器の抵抗値を切り換えた上で前記Ａ／Ｄ変換手段
から出力されるデジタル変換値が、所定の下限値以下の
場合にのみ、前記分圧抵抗値切換手段により室温付近の
温度検出に適した温度／電圧特性の異常検出用温度／電
圧変換信号になるよう前記分圧抵抗器の抵抗値を切り換
えて、前記Ａ／Ｄ変換手段から出力されるデジタル変換
値が室温としては異常な値である場合に、温度検出異常
と判定し異常対応処理を行うことを特徴とする。According to a seventh aspect of the present invention, there is provided the fixing device temperature control device according to the third aspect.
The temperature detection abnormality detecting means includes a resistance value of the voltage-dividing resistor which becomes a temperature / voltage conversion signal for fixing control having a temperature / voltage characteristic suitable for temperature detection near the fixing temperature by the voltage-dividing resistance value switching means. And the voltage / voltage characteristic suitable for detecting the temperature near room temperature by the voltage dividing resistance value switching means only when the digital conversion value output from the A / D conversion means after the switching is smaller than a predetermined lower limit value. The resistance value of the voltage-dividing resistor is switched so as to obtain an abnormal detection temperature / voltage conversion signal. If the digital conversion value output from the A / D conversion means is an abnormal value for room temperature, It is characterized in that a detection abnormality is determined and an abnormality handling process is performed.

【００２１】請求項８に記載の定着器の温度制御装置の
制御方法は、請求項４に記載の定着器の温度制御装置の
制御方法において、前記分圧抵抗値切換手段により前記
定着温度付近の温度検出に適した温度／電圧特性の定着
制御用温度／電圧変換信号になるよう前記分圧抵抗器の
抵抗値を切り換えた上で前記Ａ／Ｄ変換手段から出力さ
れるデジタル変換値が、所定の下限値以下の場合にの
み、前記分圧抵抗値切換手段により室温付近の温度検出
に適した温度／電圧特性の異常検出用温度／電圧変換信
号になるよう前記分圧抵抗器の抵抗値を切り換えて、前
記Ａ／Ｄ変換手段から出力されるデジタル変換値が室温
としては異常な値である場合に、温度検出異常と判定し
異常対応処理を行うことを特徴とする。According to a eighth aspect of the present invention, there is provided a method of controlling a temperature control device for a fixing device according to the fourth aspect of the present invention, wherein the voltage dividing resistance value switching means controls the temperature around the fixing temperature. After the resistance value of the voltage-dividing resistor is switched so as to obtain a fixing-control temperature / voltage conversion signal having a temperature / voltage characteristic suitable for temperature detection, the digital conversion value output from the A / D conversion unit becomes a predetermined value. The resistance value of the voltage-dividing resistor is changed by the voltage-dividing resistance value switching means to a temperature / voltage conversion signal for abnormality detection of temperature / voltage characteristics suitable for temperature detection near room temperature only when the voltage is equal to or less than the lower limit value of When the digital conversion value output from the A / D conversion means is an abnormal value as room temperature, it is determined that the temperature is abnormal and an abnormality handling process is performed.

【００２２】[0022]

【発明の実施の形態】以下、添付図面を参照しながら、
本発明の実施の形態を詳細に説明する。BRIEF DESCRIPTION OF THE DRAWINGS FIG.
An embodiment of the present invention will be described in detail.

【００２３】図１は、画像記録装置に内蔵され、本発明
に係る温度制御装置によりその温度が制御される定着装
置の概略構成を示している。同図において、図示しない
感光体ドラムから顕画像が転写された記録紙２５は、矢
印Ｂ方向にガイド板２４により案内され、定着器である
定着ローラ２１と、外周面がその定着ローラ２１に当接
可能に配設された加圧ローラ２２とからなるローラ対に
挾持されつつ移動する。その際に、定着ローラ２１内の
ヒータ２３により所定温度に加熱されている定着ローラ
２１からの熱と、ローラ対より受ける圧力により顕画像
が記録紙に定着される。FIG. 1 shows a schematic configuration of a fixing device which is built in an image recording apparatus and whose temperature is controlled by a temperature control device according to the present invention. In the figure, a recording paper 25 onto which a visible image has been transferred from a photosensitive drum (not shown) is guided by a guide plate 24 in the direction of arrow B, and a fixing roller 21 as a fixing device and an outer peripheral surface of the recording paper 25 contact the fixing roller 21. It moves while being pinched by a roller pair consisting of a pressure roller 22 which is provided so as to be able to contact. At this time, the visible image is fixed on the recording paper by the heat from the fixing roller 21 heated to a predetermined temperature by the heater 23 in the fixing roller 21 and the pressure received from the roller pair.

【００２４】顕画像を記録紙に確実かつ一定に定着させ
るために、定着ローラ２１の温度は、定着動作時は、所
定の定着温度（本実施の形態では１８０℃）に保持する
必要がある。そのため、定着ローラ２１の近傍には、温
度の変化により抵抗が変化する特性を持つ素子であるサ
ーミスタＲｔが配置されている。In order to fix the visible image reliably and constantly on the recording paper, the temperature of the fixing roller 21 must be maintained at a predetermined fixing temperature (180 ° C. in this embodiment) during the fixing operation. Therefore, in the vicinity of the fixing roller 21, a thermistor Rt, which is an element having a characteristic that the resistance changes with a change in temperature, is arranged.

【００２５】定着ローラ２１の温度変化に応じたサーミ
スタＲｔの抵抗値の変化は、図２に示される本発明に係
る温度制御装置１により電圧信号に変換されて処理さ
れ、温度制御装置１は、その電圧信号に応じてヒータ２
３をＯＮ／ＯＦＦ制御することにより定着ローラ２１の
温度を一定に保持する。The change in the resistance value of the thermistor Rt according to the change in the temperature of the fixing roller 21 is converted into a voltage signal by the temperature control device 1 according to the present invention shown in FIG. 2 and processed. The heater 2 according to the voltage signal
By controlling ON / OFF of 3, the temperature of the fixing roller 21 is kept constant.

【００２６】図２に示す画像処理装置において、装置制
御部２は、ＲＯＭ３に書き込まれた制御プログラムにし
たがって、ＲＡＭ４を作業領域として使用しながら定着
温度制御を行うマイクロコンピュータである。In the image processing apparatus shown in FIG. 2, the apparatus control section 2 is a microcomputer that controls the fixing temperature while using the RAM 4 as a work area in accordance with a control program written in the ROM 3.

【００２７】ＲＯＭ３は、前述したように、装置制御部
２の動作に必要な制御プログラムが書き込まれたリード
オンリメモリである。ＲＡＭ４は、前述したように、装
置制御部２の作業領域となるランダムアクセスメモリで
ある。As described above, the ROM 3 is a read-only memory in which a control program necessary for the operation of the device control unit 2 is written. The RAM 4 is a random access memory serving as a work area of the device control unit 2 as described above.

【００２８】ヒータ制御部７は、装置制御部２からのＯ
Ｎ／ＯＦＦ指示に応じて図示しない電源から前述したヒ
ータ２３への電力供給をＯＮ／ＯＦＦ制御するもので、
機械的なリレーや、トライアック等により電気的な断続
回路により構成されるものである。The heater control unit 7 receives the O from the device control unit 2.
The ON / OFF control of the power supply from the power source (not shown) to the heater 23 described above is performed in response to the N / OFF instruction.
It is configured by an electrical intermittent circuit such as a mechanical relay or a triac.

【００２９】サーミスタＲｔは、図１に示したように定
着ローラ２１の近傍に配置されて定着ローラ２１を温度
を検出するものである。抵抗Ｒ２はサーミスタＲｔと直
列接続されて、基準電圧発生部６が発生する基準電圧Ｖ
ｒｅｆを分圧するものである。また、抵抗Ｒ２とサーミ
スタＲｔとの接続点からは、温度／電圧変換信号が取り
出されたＡ／Ｄコンバータ５に入力される。また、抵抗
Ｒ２とサーミスタＲｔとの接続点には、スイッチＳＷを
介してていこうＲ１が接続されている。スイッチＳＷ
は、装置制御部２からの制御によりＯＮ／ＯＦＦされ
る。The thermistor Rt is disposed near the fixing roller 21 as shown in FIG. 1 and detects the temperature of the fixing roller 21. The resistor R2 is connected in series with the thermistor Rt, and the reference voltage V
ref is divided. Further, from a connection point between the resistor R2 and the thermistor Rt, a temperature / voltage conversion signal is input to the A / D converter 5 from which the temperature / voltage conversion signal is extracted. A connection point R1 between the resistor R2 and the thermistor Rt is connected via a switch SW. Switch SW
Is turned ON / OFF under the control of the device control unit 2.

【００３０】したがって、スイッチＳＷがＯＦＦのとき
には、抵抗Ｒ２は、サーミスタＲｔと共に基準電圧を分
圧する分圧抵抗を構成し、スイッチＳＷがＯＮのときに
は、抵抗Ｒ２と抵抗Ｒ１との並列接続が、サーミスタＲ
ｔと共に基準電圧を分圧する分圧抵抗を構成することに
なる。Therefore, when the switch SW is OFF, the resistor R2 constitutes a voltage dividing resistor for dividing the reference voltage together with the thermistor Rt. When the switch SW is ON, the parallel connection of the resistor R2 and the resistor R1 is connected to the thermistor R1. R
A voltage dividing resistor that divides the reference voltage together with t is configured.

【００３１】ここで、スイッチＳＷがＯＮの場合の抵抗
Ｒ２及び抵抗Ｒ１とサーミスタＲｔとの接続点から取り
出される温度／電圧変換信号を、定着制御用温度／電圧
変換信号Ｖｈと称し、スイッチＳＷがＯＦＦの場合の抵
抗Ｒ２とサーミスタＲｔとの接続点から取り出される温
度／電圧変換信号を、異常検出用温度／電圧変換信号Ｖ
ｌと称するものとする。Here, the temperature / voltage conversion signal taken out from the connection point between the resistors R2 and R1 and the thermistor Rt when the switch SW is ON is referred to as a fixing control temperature / voltage conversion signal Vh. The temperature / voltage conversion signal taken out from the connection point between the resistor R2 and the thermistor Rt in the OFF state is converted into the abnormality detection temperature / voltage conversion signal V
It shall be called l.

【００３２】Ａ／Ｄコンバータ５は、入力される温度／
電圧変換信号を０Ｖから基準電圧発生部６が発生するＶ
ｒｅｆの範囲内で８ビット２５６階調の値０ないし値２
５５までのデジタル変換値にアナログ／デジタル変換す
るものである。The A / D converter 5 receives the input temperature /
When the voltage conversion signal is changed from 0V to V
Within the range of ref, 8-bit 256 gradation values 0 to 2
It performs analog / digital conversion to digital conversion values up to 55.

【００３３】ここで、定着制御用温度／電圧変換信号Ｖ
ｈをＡ／Ｄ変換して出力されるデジタル変換値を変換値
Ａ／Ｄｈと称し、異常検出用温度／電圧変換信号Ｖｌを
Ａ／Ｄ変換して出力されるデジタル変換値を変換値Ａ／
Ｄｌと称するものとする。Here, the fixing control temperature / voltage conversion signal V
The digital conversion value output after A / D conversion of h is referred to as a conversion value A / Dh, and the digital conversion value output after A / D conversion of the abnormality detection temperature / voltage conversion signal Vl is converted value A / Dh.
Dl.

【００３４】また、本実施の形態では、基準電圧発生部
６が発生し、Ａ／Ｄコンバータ５に基準電圧として供給
されると共にサーミスタＲｔとＲ２（及びＲ１）との直
列抵抗に供給されるＶｒｅｆは３Ｖであるとし、抵抗Ｒ
２の抵抗値は、３３ｋΩであるとし、抵抗Ｒ１の抵抗値
は、１．７４ｋΩであるとする。スイッチＳＷがＯＮさ
れた場合の抵抗Ｒ２と抵抗Ｒ１との並列接続による分圧
抵抗の抵抗値は、１．６５３ｋΩとなる。In this embodiment, the reference voltage generator 6 generates the reference voltage Vref which is supplied to the A / D converter 5 as a reference voltage and supplied to the series resistor of the thermistors Rt and R2 (and R1). Is 3V and the resistance R
2 has a resistance of 33 kΩ, and the resistance of the resistor R1 has a resistance of 1.74 kΩ. When the switch SW is turned on, the resistance value of the voltage dividing resistor due to the parallel connection of the resistor R2 and the resistor R1 is 1.653 kΩ.

【００３５】図３に、サーミスタＲｔの温度と、定着制
御用温度／電圧変換信号Ｖｈ及び異常検出用温度／電圧
変換信号Ｖｌとの関係を示す。FIG. 3 shows the relationship between the temperature of the thermistor Rt, the fixing control temperature / voltage conversion signal Vh, and the abnormality detection temperature / voltage conversion signal Vl.

【００３６】また、図４に、−１０℃から３００℃の範
囲のサーミスタＲｔの温度と、サーミスタＲｔの抵抗値
と、定着制御用温度／電圧変換信号Ｖｈと、変換値Ａ／
Ｄｈと、異常検出用温度／電圧変換信号Ｖｌと、変換値
Ａ／Ｄｌとの対応について示す。FIG. 4 shows the temperature of the thermistor Rt in the range of -10 ° C. to 300 ° C., the resistance value of the thermistor Rt, the fixing control temperature / voltage conversion signal Vh, and the conversion value A /
The correspondence between Dh, the abnormality detection temperature / voltage conversion signal Vl, and the conversion value A / Dl will be described.

【００３７】図４に示されるように、サーミスタＲｔの
抵抗値は、温度が低くなるにつれて急激に値が大きくな
っていく一方、温度が高くなるにつれて急激に値が小さ
くなる非線形な特性を示す。As shown in FIG. 4, the resistance value of the thermistor Rt has a nonlinear characteristic in which the value increases rapidly as the temperature decreases, and decreases rapidly as the temperature increases.

【００３８】したがって、図３に示すように、分圧抵抗
値の違い（Ｖｈの場合には３３ｋΩ、Ｖｌの場合には
１．６５３ｋΩ）によって、温度／電圧変換信号の温度
／電圧特性が大きくことなる。Therefore, as shown in FIG. 3, the temperature / voltage characteristic of the temperature / voltage conversion signal is large due to the difference in the voltage dividing resistance (33 kΩ for Vh, 1.653 kΩ for Vl). Become.

【００３９】図３を見て明らかなように、定着制御用温
度／電圧変換信号Ｖｈの温度／電圧特性は、定着温度
（１８０℃）付近での傾きが大きく、温度変化に対する
電圧変化が大きい反面、０℃ないし３０℃の室温付近で
は、ほとんど０Ｖ付近でわずかに変化するだけで、温度
変化に対する電圧変化が非常に小さい。As is apparent from FIG. 3, the temperature / voltage characteristic of the fixing control temperature / voltage conversion signal Vh has a large gradient near the fixing temperature (180 ° C.), and the voltage change with respect to the temperature change is large. In the vicinity of room temperature between 0.degree. C. and 30.degree. C., there is only a slight change near 0 V, and the voltage change with respect to the temperature change is very small.

【００４０】一方、定着制御用温度／電圧変換信号Ｖｌ
の温度／電圧特性は、室温付近での傾きが大きく、温度
変化に対する電圧変化が大きい反面、定着温度（１８０
℃）付近では、ほとんど３Ｖ付近でわずかに変化するだ
けで、温度変化に対する電圧変化が非常に小さい。On the other hand, the fixing control temperature / voltage conversion signal Vl
The temperature / voltage characteristic has a large slope near room temperature and a large voltage change with respect to a temperature change.
In the vicinity of (° C.), there is only a slight change at around 3 V, and the voltage change with respect to the temperature change is very small.

【００４１】そのため、図４に示すように変換値Ａ／Ｄ
ｈは、室温では０ないし２の値しかとらず、仮に、定着
制御用温度／電圧変換信号Ｖｈにより室温付近の温度を
検出しようとすると、変換値Ａ／Ｄｈの値が、サーミス
タＲｔの断線やコネクタ抜けが発生した際に出力される
値である０付近の値とほとんど区別がつかず、サーミス
タＲｔの断線やコネクタ抜け等の温度検出の異常を正確
に検出することできない。Therefore, as shown in FIG.
h takes only a value of 0 to 2 at room temperature. If an attempt is made to detect a temperature near room temperature by the fixing control temperature / voltage conversion signal Vh, the value of the conversion value A / Dh may be determined by the disconnection of the thermistor Rt or the like. It is almost indistinguishable from a value near 0 which is a value output when a connector disconnection occurs, and it is not possible to accurately detect abnormalities in temperature detection such as disconnection of the thermistor Rt or disconnection of the connector.

【００４２】しかし、図４に示すように変換値Ａ／Ｄｌ
は、室温では１０ないし３７の値をとり、異常検出用温
度／電圧変換信号Ｖｌにより室温付近の温度を検出すれ
ば、変換値Ａ／Ｄｈの値が、サーミスタＲｔの断線やコ
ネクタ抜けが発生した際に出力される値である０とはっ
きり区別でき、サーミスタＲｔの断線やコネクタ抜け等
の温度検出の異常を正確に検出することができることに
なる。However, as shown in FIG.
Takes a value of 10 to 37 at room temperature, and if the temperature around room temperature is detected by the abnormality detection temperature / voltage conversion signal Vl, the converted value A / Dh may cause disconnection of the thermistor Rt or disconnection of the connector. In this case, the output value can be clearly distinguished from 0, which means that an abnormality in temperature detection such as disconnection of the thermistor Rt or disconnection of the connector can be accurately detected.

【００４３】そこで、温度制御装置１は、図５に示す定
着温度制御を行う。Therefore, the temperature control device 1 performs the fixing temperature control shown in FIG.

【００４４】同図において、温度制御装置１の装置制御
部２は、装置電源が投入されると定着温度制御を開始す
る。その場合、サーミスタＲｔが検出する定着ローラ２
１の温度は、前回の電源断から相当時間が経過していれ
ば室温まで低下しており、前回の電源断から間がなけれ
ば、室温以上定着温度以下の温度になっているはずであ
る。In FIG. 1, the apparatus control section 2 of the temperature control apparatus 1 starts fixing temperature control when the apparatus power is turned on. In that case, the fixing roller 2 detected by the thermistor Rt
The temperature of 1 should have dropped to room temperature if a considerable time has elapsed since the previous power-off, and if it has not been long since the previous power-off, it should have been between room temperature and the fixing temperature.

【００４５】装置制御部２は、先ず、スイッチＳＷをＯ
ＦＦして（処理１０１）、Ａ／Ｄコンバータ５に異常検
出用温度／電圧変換信号Ｖｌが入力されるようにして、
信号ＶｌのＡ／Ｄ変換値Ａ／Ｄｌを読み取り（処理１０
２）、変換値Ａ／Ｄｌの値が６以下か、すなわち、図４
に示すように、温度に換算して−１０℃以下に相当す
る、サーミスタＲｔが検出する定着ローラ２１の温度と
してはあり得ないほど低温であるか否かを判断する（判
断１０３）。The device control unit 2 first sets the switch SW to O
FF (process 101), so that the temperature / voltage conversion signal Vl for abnormality detection is input to the A / D converter 5,
The A / D conversion value A / Dl of the signal Vl is read (processing 10
2) Whether the value of the conversion value A / Dl is 6 or less, that is, FIG.
As shown in (3), it is determined whether or not the temperature of the fixing roller 21 detected by the thermistor Rt, which is equivalent to -10 ° C. or less, is so low as to be impossible (decision 103).

【００４６】変換値Ａ／Ｄｌの値が６以下である場合は
（判断１０３のＹｅｓ）、ヒータ２３をＯＮすることな
く装置動作を止めて、警告表示を行う等の温度検出異常
に対応したエラー処理を行う（処理１０９）。If the value of the conversion value A / Dl is 6 or less (Yes in the judgment 103), an error corresponding to the temperature detection abnormality such as stopping the operation of the apparatus without turning on the heater 23 and displaying a warning is displayed. Processing is performed (processing 109).

【００４７】変換値Ａ／Ｄｌの値が６以上である場合は
（判断１０３のＮｏ）、サーミスタＲｔに断線やコネク
タ抜けがなく、定着ローラ２１の温度ら正しく検出して
いるといえるため、スイッチＳＷをＯＮして（処理１０
４）、Ａ／Ｄコンバータ５に定着制御用温度／電圧変換
信号Ｖｈが入力されるようにして、信号ＶｈのＡ／Ｄ変
換値Ａ／Ｄｈを読み取り（処理１０５）、変換値Ａ／Ｄ
ｈの値が、図４に示すように、温度１８０℃に相当する
値１２６以下か否かを判断し、値１２６以下であれば
（判断１０６のＹｅｓ）、ヒータ２３をＯＮし（処理１
０７）、値１２６以上であれば（判断１０６のＮｏ）、
ヒータ２３をＯＦＦして（処理１０７）、処理１０１に
戻る。なお、判断１０６がＹｅｓとなって処理１０７で
ヒータがＯＮしてからの次のループでまた判断１０６が
Ｙｅｓとなった場合には、処理１０７ではヒータＯＮ状
態が継続されることを意味する。同様に、判断１０６が
Ｎｏとなって処理１０８でヒータがＯＦＦしてからの次
のループでまた判断１０６がＮｏとなった場合には、処
理１０７ではヒータＯＦＦ状態が継続されることを意味
する。If the value of the conversion value A / Dl is 6 or more (No in decision 103), it can be said that there is no disconnection or disconnection of the connector in the thermistor Rt and the temperature of the fixing roller 21 is correctly detected. Turn on the SW (Process 10
4) The A / D converter 5 reads the A / D conversion value A / Dh of the signal Vh by inputting the fixing control temperature / voltage conversion signal Vh to the A / D converter 5 (processing 105).
As shown in FIG. 4, it is determined whether or not the value of h is equal to or less than a value 126 corresponding to a temperature of 180 ° C. If the value of h is equal to or less than 126 (Yes in determination 106), the heater 23 is turned on (processing 1).
07) If the value is equal to or greater than 126 (No in decision 106),
The heater 23 is turned off (Step 107), and the process returns to Step 101. Note that if the determination 106 becomes Yes in the next loop after the heater is turned on in the process 107 after the determination 106 becomes Yes, it means that the heater ON state is continued in the process 107. Similarly, if the determination 106 is No in the next loop after the determination 106 is No and the heater is turned off in the processing 108, it means that the heater OFF state is continued in the processing 107. .

【００４８】図５に示す定着温度制御手順に代えて、図
６に示す定着温度制御手順を行うようにしてもよい。Instead of the fixing temperature control procedure shown in FIG. 5, a fixing temperature control procedure shown in FIG. 6 may be performed.

【００４９】図６において、装置制御部２は、先ず、ス
イッチＳＷをＯＮして（処理２０１）、Ａ／Ｄコンバー
タ５に定着制御用温度／電圧変換信号Ｖｈが入力される
ようにして、信号ＶｈのＡ／Ｄ変換値Ａ／Ｄｈを読み取
り（処理２０２）、変換値Ａ／Ｄｈの値が、図４に示す
ように、値３０以上か否かを判断し、値３０以下であれ
ば（判断２０３のＹｅｓ）、判断２０９に移行して、定
着温度の制御を行う。これは、室温では温度検出精度が
低い定着制御用温度／電圧変換信号Ｖｈではあるが、温
度にして１０５℃に相当する、サーミスタＲｔの断線や
コネクタ抜けに起因する極端に小さな値と十分区別可能
な大きな値３０を、変換値Ａ／Ｄｈとして出力すれば、
異常検出用温度／電圧変換信号Ｖｌによる温度検出を行
うまでもなく、サーミスタＲｔの断線やコネクタ抜けは
発生してしないといえるため、わざわざ、スイッチＳＷ
をＯＮ／ＯＦＦして定着制御用温度／電圧変換信号Ｖｌ
を読み取る必要がないためである。そのように、不必要
な信号Ｖｌを読み取りを省くことで、処理手順を簡単化
できると共に、スイッチＳＷのＯＮ／ＯＦＦ回数を最小
限にでき、スイッチＳＷの寿命をのばすことができる。In FIG. 6, first, the apparatus control section 2 turns on the switch SW (step 201), so that the fixing control temperature / voltage conversion signal Vh is inputted to the A / D converter 5, and The A / D conversion value A / Dh of Vh is read (process 202), and it is determined whether or not the value of the conversion value A / Dh is 30 or more as shown in FIG. The determination 203 is Yes), and the process proceeds to the determination 209 to control the fixing temperature. This is a fixing control temperature / voltage conversion signal Vh whose temperature detection accuracy is low at room temperature, but can be sufficiently distinguished from an extremely small value corresponding to 105 ° C. in temperature due to disconnection of the thermistor Rt or disconnection of the connector. By outputting a very large value 30 as the conversion value A / Dh,
Since it can be said that disconnection of the thermistor Rt and disconnection of the connector do not occur without performing temperature detection using the abnormality detection temperature / voltage conversion signal Vl, the switch SW is bothersome.
Is turned ON / OFF to change the fixing control temperature / voltage conversion signal Vl.
This is because there is no need to read. By omitting the reading of the unnecessary signal Vl, the processing procedure can be simplified, the number of ON / OFF operations of the switch SW can be minimized, and the life of the switch SW can be extended.

【００５０】値３０以下であれば（判断２０３のＮ
ｏ）、ヒータ２３をＯＦＦして（処理２０４）、Ａ／Ｄ
コンバータ５に異常検出用温度／電圧変換信号Ｖｌが入
力されるようにして、信号ＶｌのＡ／Ｄ変換値Ａ／Ｄｌ
を読み取り（処理２０５）、変換値Ａ／Ｄｌの値が６以
下か、すなわち、図４に示すように、温度に換算して−
１０℃以下に相当する、サーミスタＲｔが検出する定着
ローラ２１の温度としてはあり得ないほど低温であるか
否かを判断する（判断２０６）。If the value is 30 or less (N in decision 203)
o), the heater 23 is turned off (process 204), and the A / D
The temperature / voltage conversion signal Vl for abnormality detection is input to the converter 5 so that the A / D conversion value A / Dl
Is read (process 205), and whether the value of the conversion value A / Dl is 6 or less, that is, as shown in FIG.
It is determined whether the temperature of the fixing roller 21 detected by the thermistor Rt, which is equal to or less than 10 ° C., is so low as to be impossible (decision 206).

【００５１】変換値Ａ／Ｄｌの値が６以下である場合は
（判断２０６のＹｅｓ）、ヒータ２３をＯＮすることな
く装置動作を止めて、警告表示を行う等の温度検出異常
に対応したエラー処理を行う（処理２１２）。If the value of the conversion value A / Dl is 6 or less (Yes in decision 206), an error corresponding to the temperature detection abnormality such as stopping the device operation without turning on the heater 23 and displaying a warning is displayed. Processing is performed (processing 212).

【００５２】変換値Ａ／Ｄｌの値が６以上である場合は
（判断２０７のＮｏ）、サーミスタＲｔに断線やコネク
タ抜けがなく、定着ローラ２１の温度ら正しく検出して
いるといえるため、スイッチＳＷをＯＮして（処理２０
７）、Ａ／Ｄコンバータ５に定着制御用温度／電圧変換
信号Ｖｈが入力されるようにして、信号ＶｈのＡ／Ｄ変
換値Ａ／Ｄｈを読み取り（処理２０８）、判断２０９に
移行する。If the value of the conversion value A / Dl is 6 or more (No in decision 207), it can be said that there is no disconnection or disconnection of the connector in the thermistor Rt and the temperature of the fixing roller 21 is correctly detected. Turn on the SW (processing 20
7) The A / D converter 5 reads the A / D conversion value A / Dh of the signal Vh so that the fixing control temperature / voltage conversion signal Vh is input to the A / D converter 5 (processing 208), and proceeds to the judgment 209.

【００５３】判断２０９では、変換値Ａ／Ｄｈの値が、
図４に示すように、温度１８０℃に相当する値１２６以
下か否かを判断し、値１２６以下であれば（判断２０９
のＹｅｓ）、ヒータ２３をＯＮし（処理２１０）、値１
２６以上であれば（判断２０９のＮｏ）、ヒータ２３を
ＯＦＦして（処理２１１）、処理２０１に戻る。In the judgment 209, the value of the conversion value A / Dh is
As shown in FIG. 4, it is determined whether or not the value is equal to or less than a value 126 corresponding to a temperature of 180 ° C.
Yes), the heater 23 is turned on (process 210), and the value 1
If it is equal to or greater than 26 (No in decision 209), the heater 23 is turned off (process 211) and the process returns to process 201.

【００５４】このように本実施の形態によれば、サーミ
スタＲｔの断線やコネクタ抜け等の温度検出の異常を安
全かつ確実に検出できるようになる。As described above, according to the present embodiment, abnormalities in temperature detection such as disconnection of the thermistor Rt and disconnection of the connector can be detected safely and reliably.

【００５５】なお、以上説明した実施の形態では、Ａ／
Ｄコンバータ５に入力される温度／電圧変換信号の特性
を、定着制御用温度／電圧変換信号Ｖｈまたは異常検出
用温度／電圧変換信号Ｖｌにするために、抵抗Ｒ２に必
要に応じて抵抗Ｒ１をスイッチＳＷを介して並列接続す
ることにより、サーミスタＲｔの分圧抵抗の抵抗値を３
３ｋΩまたは１．６５３ｋΩになるようにしたが、本発
明は、サーミスタＲｔの分圧抵抗の抵抗値の変更方法に
より限定されるものではなく、例えば、３３ｋΩの抵抗
器と、１．６５３ｋΩの抵抗器とを選択的にサーミスタ
Ｒｔに接続するような構成や、可変抵抗器の抵抗値の変
更による方法に対しても同様に適用可能なものである。
また、本実施の形態では、室温が０℃ないし３０℃で、
定着温度が１８０℃である場合に適応するように、サー
ミスタＲｔの特性と分圧抵抗の抵抗値の組合せを設定し
て、定着制御用温度／電圧変換信号Ｖｈや異常検出用温
度／電圧変換信号Ｖｌの特性を実現したが、室温の温度
範囲や、定着温度に応じて、サーミスタＲｔの特性と分
圧抵抗の抵抗値の組合せは最適に設定されるべきもので
ある。In the embodiment described above, A /
In order to change the characteristics of the temperature / voltage conversion signal input to the D converter 5 to the fixing control temperature / voltage conversion signal Vh or the abnormality detection temperature / voltage conversion signal Vl, the resistor R1 may be replaced with the resistor R1 as necessary. By connecting in parallel via the switch SW, the resistance value of the voltage-dividing resistor of the thermistor Rt becomes 3
Although the resistance is set to 3 kΩ or 1.653 kΩ, the present invention is not limited by the method of changing the resistance value of the voltage dividing resistance of the thermistor Rt. For example, a 33 kΩ resistor and a 1.653 kΩ resistor Can be similarly applied to a configuration in which is selectively connected to the thermistor Rt or a method in which the resistance value of the variable resistor is changed.
In the present embodiment, the room temperature is 0 ° C. to 30 ° C.,
The combination of the characteristics of the thermistor Rt and the resistance value of the voltage dividing resistor is set so as to adapt to the case where the fixing temperature is 180 ° C., and the fixing control temperature / voltage conversion signal Vh and the abnormality detection temperature / voltage conversion signal are set. Although the characteristic of Vl is realized, the combination of the characteristic of the thermistor Rt and the resistance value of the voltage dividing resistor should be set optimally according to the temperature range of the room temperature and the fixing temperature.

【００５６】[0056]

【発明の効果】請求項１または２に係る発明によれば、
本来定着温度制御用の前記サーミスタの分圧抵抗の抵抗
値を、室温付近の温度を精度よく検出できる温度／電圧
特性の異常検出用温度／電圧変換信号になるよう切り換
えて、温度検出するようにしたため、異常検出用温度／
電圧変換信号は、室温を正しく検出した場合には相当レ
ベルとなり、前記サーミスタの断線やコネクタ抜けの発
生に起因する温度検出以上の発生の際に前記温度／電圧
変換信号として出力されるほとんど０レベルの信号と明
確に区別できるようになる。したがって、定着器の温度
検出の異常の有無を安全かつ確実に検出することができ
るようになるという効果が得られる。According to the first or second aspect of the present invention,
The resistance value of the voltage dividing resistor of the thermistor for controlling the fixing temperature is switched so as to be a temperature / voltage conversion signal for abnormality detection of a temperature / voltage characteristic capable of accurately detecting a temperature around room temperature so as to detect the temperature. The temperature for abnormality detection /
The voltage conversion signal has a considerable level when the room temperature is correctly detected, and is almost zero level which is output as the temperature / voltage conversion signal when the temperature is detected beyond the temperature detection caused by disconnection of the thermistor or disconnection of the connector. Signals can be clearly distinguished. Therefore, an effect is obtained that the presence or absence of abnormality in the temperature detection of the fixing device can be detected safely and reliably.

【００５７】請求項３または４に係る発明によれば、前
記定着制御用温度／電圧変換信号及び前記異常検出用温
度／電圧変換信号が同時に生じることがないことに鑑み
て１つのＡ／Ｄ変換手段により時分割でＡ／Ｄ変換して
デジタル変換値を得るようにしたため、その分構成の簡
略化及び低コスト化が可能となる効果が得られる。According to the third or fourth aspect of the present invention, one A / D converter takes into account that the fixing control temperature / voltage conversion signal and the abnormality detection temperature / voltage conversion signal do not occur simultaneously. Since the digitally converted value is obtained by performing A / D conversion in a time-division manner by means, an effect that the configuration can be simplified and the cost can be reduced accordingly.

【００５８】請求項５または６に係る発明によれば、室
温では温度検出精度が低い前記定着制御用温度／電圧変
換信号ではあるが、室温よりかなり高温になれば、サー
ミスタの断線やコネクタ抜けに起因する極端に小さな信
号レベルと十分区別可能な大きなレベルの信号を出力す
ることになるため、前記異常検出用温度／電圧変換信号
による温度検出を行うまでもなく、サーミスタの断線や
コネクタ抜けは発生してしないといえることに鑑みて、
わざわざ、前記定着制御用温度／電圧変換信号により温
度検出の異常発生の有無の検出処理の実行を最低限に抑
えることができる。したがって、処理手順を簡単化でき
ると共に、分圧抵抗値切換手段により抵抗値切換回数が
最低限にできかの切換回路の長寿命化を図ることが可能
となる効果が得られる。According to the fifth or sixth aspect of the present invention, although the temperature / voltage conversion signal for fixing control has a low temperature detection accuracy at room temperature, if the temperature becomes considerably higher than room temperature, the thermistor may be disconnected or the connector may be disconnected. Since a signal of a large level that can be sufficiently distinguished from an extremely small signal level due to the output is output, disconnection of the thermistor and disconnection of the connector occur without performing temperature detection by the abnormality detection temperature / voltage conversion signal. In light of what you can't do,
It is possible to minimize the execution of the process of detecting the occurrence of an abnormality in the temperature detection by the fixing control temperature / voltage conversion signal. Therefore, the processing procedure can be simplified, and the effect of extending the life of the switching circuit, which can be minimized by the number of resistance value switching by the voltage dividing resistance value switching means, can be obtained.

【００５９】請求項７または８に係る発明によれば、室
温では温度検出精度が低い前記定着制御用温度／電圧変
換信号ではあるが、室温よりかなり高温になれば、サー
ミスタの断線やコネクタ抜けに起因する極端に小さな信
号レベルと十分区別可能な大きなレベルの信号を出力す
ることになるため、前記異常検出用温度／電圧変換信号
による温度検出を行うまでもなく、サーミスタの断線や
コネクタ抜けは発生してしないといえることに鑑みて、
わざわざ、前記定着制御用温度／電圧変換信号により温
度検出の異常発生の有無の検出処理の実行を最低限に抑
えることができる。したがって、処理手順を簡単化でき
ると共に、分圧抵抗値切換手段により抵抗値切換回数が
最低限にできかの切換回路の長寿命化を図ることが可能
となる効果が得られる。According to the seventh or eighth aspect of the present invention, although the temperature / voltage conversion signal for fixing control has a low temperature detection accuracy at room temperature, if the temperature becomes significantly higher than room temperature, the thermistor may be disconnected or the connector may be disconnected. Since a signal of a large level that can be sufficiently distinguished from an extremely small signal level due to the output is output, disconnection of the thermistor and disconnection of the connector occur without performing temperature detection by the abnormality detection temperature / voltage conversion signal. In light of what you can't do,
It is possible to minimize the execution of the process of detecting the occurrence of an abnormality in the temperature detection by the fixing control temperature / voltage conversion signal. Therefore, the processing procedure can be simplified, and the effect of extending the life of the switching circuit, which can be minimized by the number of resistance value switching by the voltage dividing resistance value switching means, can be obtained.

【図面の簡単な説明】[Brief description of the drawings]

【図１】本発明の実施の形態に係る温度制御装置により
温度制御される定着装置を示す図である。FIG. 1 is a diagram showing a fixing device whose temperature is controlled by a temperature control device according to an embodiment of the present invention.

【図２】本発明の実施の形態に係る温度制御装置の構成
について示す図である。FIG. 2 is a diagram showing a configuration of a temperature control device according to an embodiment of the present invention.

【図３】本発明の実施の形態に係る温度制御装置におけ
る定着制御用温度／電圧変換信号及び異常検出用温度／
電圧変換信号の温度−電圧特性を示す図である。FIG. 3 shows a fixing control temperature / voltage conversion signal and an abnormality detection temperature / temperature in the temperature control device according to the embodiment of the present invention.
FIG. 4 is a diagram illustrating a temperature-voltage characteristic of a voltage conversion signal.

【図４】本発明の実施の形態に係る温度制御装置におけ
る定着ローラの温度、サーミスタ抵抗値、定着制御用温
度／電圧変換信号、そのデジタル変換値、異常検出用温
度／電圧変換信号、及び、そのデジタル変換値の対応に
ついて示す図である。FIG. 4 shows a fixing roller temperature, a thermistor resistance value, a fixing control temperature / voltage conversion signal, a digital conversion value thereof, an abnormality detection temperature / voltage conversion signal, and a fixing roller temperature control device according to an embodiment of the present invention. It is a figure showing the correspondence of the digital conversion value.

【図５】本発明の実施の形態に係る温度制御装置におけ
る定着温度制御処理手順の第１例について示すフローチ
ャートである。FIG. 5 is a flowchart illustrating a first example of a fixing temperature control processing procedure in the temperature control device according to the embodiment of the present invention.

【図６】本発明の実施の形態に係る温度制御装置におけ
る定着温度制御処理手順の第２例について示すフローチ
ャートである。FIG. 6 is a flowchart illustrating a second example of a fixing temperature control processing procedure in the temperature control device according to the embodiment of the present invention.

【符号の説明】[Explanation of symbols]

１ 温度制御装置 ２ 装置制御部 ３ ＲＯＭ ４ ＲＡＭ ５ Ａ／Ｄコンバータ ６ 基準電圧発生部 ７ ヒータ制御部 ２１ 定着ローラ ２２ 加圧ローラ ２３ ヒータ ２４ ガイド板 ２５ 記録紙 Ｒ１、Ｒ２ 抵抗 Ｒｔ サーミスタ ＳＷ スイッチ REFERENCE SIGNS LIST 1 Temperature control device 2 Device control unit 3 ROM 4 RAM 5 A / D converter 6 Reference voltage generation unit 7 Heater control unit 21 Fixing roller 22 Pressure roller 23 Heater 24 Guide plate 25 Recording paper R1, R2 Resistance Rt Thermistor SW switch

Claims (8)

【特許請求の範囲】[Claims] 【請求項１】 定着器を加熱するヒータへの供給電力を
制御することにより前記定着器の温度を定着温度に制御
する定着器の温度制御装置において、 前記定着器の温度変化に応じてその抵抗値が変化するサ
ーミスタと、前記サーミスタに直列接続され抵抗値が可
変に構成された分圧抵抗器と、前記サーミスタと前記分
圧抵抗器とを直列接続して構成される合成抵抗の両端に
所定の電圧を印加してその接続点から得られる温度／電
圧変換信号が、前記定着温度付近の温度を精度よく検出
できる温度／電圧特性の定着制御用温度／電圧変換信
号、または、室温付近の温度を精度よく検出できる温度
／電圧特性の異常検出用温度／電圧変換信号になるよう
前記分圧抵抗器の抵抗値を切り換える分圧抵抗値切換手
段と、前記定着制御用温度／電圧変換信号をアナログ／
デジタル変換する定着制御用Ａ／Ｄ変換手段と、異常検
出用温度／電圧変換信号をアナログ／デジタル変換する
異常検出用Ａ／Ｄ変換手段と、前記分圧抵抗値切換手段
により前記定着温度付近の温度検出に適した温度／電圧
特性の定着制御用温度／電圧変換信号になるよう前記分
圧抵抗器の抵抗値を切り換えた上で前記定着制御用Ａ／
Ｄ変換手段から出力されるデジタル変換値が、前記定着
温度に対応した所定の値になるよう前記定着器を加熱す
るヒータへの供給電力を制御して前記定着器の温度を前
記定着温度に制御する定着温度制御手段と、前記分圧抵
抗値切換手段により室温付近の温度検出に適した温度／
電圧特性の異常検出用温度／電圧変換信号になるよう前
記分圧抵抗器の抵抗値を切り換えた上で前記異常検出用
Ａ／Ｄ変換手段から出力されるデジタル変換値が室温と
しては異常な値である場合に、前記サーミスタによる温
度検出の異常と判定し異常対応処理を行う温度検出異常
検出手段とを備えたことを特徴とする定着器の温度制御
装置。An apparatus for controlling a temperature of a fixing device to a fixing temperature by controlling power supplied to a heater for heating the fixing device, wherein a resistance of the fixing device is controlled in accordance with a temperature change of the fixing device. A thermistor having a variable value, a voltage-dividing resistor connected in series to the thermistor and having a variable resistance value, and a predetermined resistor at both ends of a combined resistor formed by connecting the thermistor and the voltage-dividing resistor in series. Is applied, the temperature / voltage conversion signal obtained from the connection point is a temperature / voltage conversion signal for fixing control having a temperature / voltage characteristic capable of accurately detecting a temperature near the fixing temperature, or a temperature near room temperature. Resistance-value switching means for switching the resistance value of the voltage-dividing resistor so as to provide a temperature / voltage conversion signal for temperature / voltage characteristic abnormality detection capable of accurately detecting the temperature / voltage characteristic, and the fixing control temperature / voltage conversion. Analog the issue /
A / D conversion means for fixing control for digital conversion, A / D conversion means for abnormality detection for analog / digital conversion of a temperature / voltage conversion signal for abnormality detection, The resistance value of the voltage dividing resistor is switched so as to obtain a temperature / voltage conversion signal for fixing control having a temperature / voltage characteristic suitable for temperature detection, and then the fixing control A /
The temperature of the fixing unit is controlled to the fixing temperature by controlling the power supplied to the heater for heating the fixing unit so that the digital conversion value output from the D conversion unit becomes a predetermined value corresponding to the fixing temperature. And a temperature / temperature suitable for detecting a temperature near room temperature by the fixing temperature control means and the voltage dividing resistance value switching means.
After the resistance value of the voltage dividing resistor is switched so as to become a temperature / voltage conversion signal for voltage characteristic abnormality detection, the digital conversion value output from the abnormality detection A / D conversion means is an abnormal value as room temperature. A temperature detection abnormality detecting means for judging an abnormality in the temperature detection by the thermistor and performing an abnormality handling process. 【請求項２】 定着器を加熱するヒータへの供給電力を
制御することにより前記定着器の温度を定着温度に制御
する定着器の温度制御装置の制御方法において、 前記定着器の温度変化に応じてその抵抗値が変化するサ
ーミスタと、前記サーミスタに直列接続され抵抗値が可
変に構成された分圧抵抗器と、前記サーミスタと前記分
圧抵抗器とを直列接続して構成される合成抵抗の両端に
所定の電圧を印加してその接続点から得られる温度／電
圧変換信号が、前記定着温度付近の温度を精度よく検出
できる温度／電圧特性の定着制御用温度／電圧変換信
号、または、室温付近の温度を精度よく検出できる温度
／電圧特性の異常検出用温度／電圧変換信号になるよう
前記分圧抵抗器の抵抗値を切り換える分圧抵抗値切換手
段と、前記定着制御用温度／電圧変換信号をアナログ／
デジタル変換する定着制御用Ａ／Ｄ変換手段と、異常検
出用温度／電圧変換信号をアナログ／デジタル変換する
異常検出用Ａ／Ｄ変換手段とを有し、前記分圧抵抗値切
換手段により前記定着温度付近の温度検出に適した温度
／電圧特性の定着制御用温度／電圧変換信号になるよう
前記分圧抵抗器の抵抗値を切り換えた上で前記定着制御
用Ａ／Ｄ変換手段から出力されるデジタル変換値が、前
記定着温度に対応した所定の値になるよう前記定着器を
加熱するヒータへの供給電力を制御して前記定着器の温
度を前記定着温度に制御する一方、前記分圧抵抗値切換
手段により室温付近の温度検出に適した温度／電圧特性
の異常検出用温度／電圧変換信号になるよう前記分圧抵
抗器の抵抗値を切り換えた上で前記異常検出用Ａ／Ｄ変
換手段から出力されるデジタル変換値が室温としては異
常な値である場合に、前記サーミスタによる温度検出の
異常と判定し異常対応処理を行うことを特徴とする定着
器の温度制御装置の制御方法。2. A method for controlling a temperature control device of a fixing device, wherein a temperature of the fixing device is controlled to a fixing temperature by controlling a power supplied to a heater for heating the fixing device, the method comprising: The thermistor having a variable resistance value, a voltage-dividing resistor connected in series to the thermistor and having a variable resistance value, and a combined resistor formed by connecting the thermistor and the voltage-dividing resistor in series. A temperature / voltage conversion signal obtained from a connection point by applying a predetermined voltage to both ends is a temperature / voltage conversion signal for fixing control having a temperature / voltage characteristic capable of accurately detecting a temperature near the fixing temperature, or room temperature. Voltage dividing resistance value switching means for switching the resistance value of the voltage dividing resistor so as to be a temperature / voltage conversion signal for temperature / voltage characteristic abnormality detection capable of accurately detecting a nearby temperature; and the fixing control temperature. Analog voltage conversion signal /
A / D conversion means for fixing control for digital conversion, and A / D conversion means for abnormality detection for analog / digital conversion of a temperature / voltage conversion signal for abnormality detection, and the fixing by the voltage dividing resistance value switching means. The resistance value of the voltage dividing resistor is switched so as to obtain a temperature / voltage conversion signal for fixing control having a temperature / voltage characteristic suitable for detecting a temperature near the temperature, and then output from the A / D conversion means for fixing control. The temperature of the fixing unit is controlled to the fixing temperature by controlling power supplied to a heater for heating the fixing unit so that the digital conversion value becomes a predetermined value corresponding to the fixing temperature, while the voltage dividing resistance is adjusted. The resistance value of the voltage dividing resistor is switched by a value switching means so as to provide a temperature / voltage conversion signal for abnormality detection of temperature / voltage characteristics suitable for detecting a temperature near room temperature, and then the A / D conversion means for abnormality detection Output from That when the digital conversion value is an abnormal value as a room temperature, a control method of the fixing device of temperature controller and performs abnormality judgment anomaly correction of the temperature detected by the thermistor. 【請求項３】 定着器を加熱するヒータへの供給電力を
制御することにより前記定着器の温度を定着温度に制御
する定着器の温度制御装置において、 前記定着器の温度変化に応じてその抵抗値が変化するサ
ーミスタと、前記サーミスタに直列接続され抵抗値が可
変に構成された分圧抵抗器と、前記サーミスタと前記分
圧抵抗器とを直列接続して構成される合成抵抗の両端に
所定の電圧を印加してその接続点から得られる温度／電
圧変換信号が、前記定着温度付近の温度を精度よく検出
できる温度／電圧特性の定着制御用温度／電圧変換信
号、または、室温付近の温度を精度よく検出できる温度
／電圧特性の異常検出用温度／電圧変換信号になるよう
前記分圧抵抗器の抵抗値を切り換える分圧抵抗値切換手
段と、前記定着制御用温度／電圧変換信号及び前記異常
検出用温度／電圧変換信号を時分割で切り換えてアナロ
グ／デジタル変換するＡ／Ｄ変換手段と、前記分圧抵抗
値切換手段により前記定着温度付近の温度検出に適した
温度／電圧特性の定着制御用温度／電圧変換信号になる
よう前記分圧抵抗器の抵抗値を切り換えた上で前記Ａ／
Ｄ変換手段から出力されるデジタル変換値が、前記定着
温度に対応した所定の値になるよう前記定着器を加熱す
るヒータへの供給電力を制御して前記定着器の温度を前
記定着温度に制御する定着温度制御手段と、前記分圧抵
抗値切換手段により室温付近の温度検出に適した温度／
電圧特性の異常検出用温度／電圧変換信号になるよう前
記分圧抵抗器の抵抗値を切り換えた上で前記Ａ／Ｄ変換
手段から出力されるデジタル変換値が室温としては異常
な値である場合に、前記サーミスタによる温度検出の異
常と判定し異常対応処理を行う温度検出異常検出手段と
を備えたことを特徴とする定着器の温度制御装置。3. A fixing device temperature control device for controlling the temperature of the fixing device to a fixing temperature by controlling electric power supplied to a heater for heating the fixing device, wherein a resistance of the fixing device in response to a temperature change of the fixing device. A thermistor having a variable value, a voltage-dividing resistor connected in series to the thermistor and having a variable resistance value, and a predetermined resistor at both ends of a combined resistor formed by connecting the thermistor and the voltage-dividing resistor in series. Is applied, the temperature / voltage conversion signal obtained from the connection point is a temperature / voltage conversion signal for fixing control having a temperature / voltage characteristic capable of accurately detecting a temperature near the fixing temperature, or a temperature near room temperature. Resistance-value switching means for switching the resistance value of the voltage-dividing resistor so as to provide a temperature / voltage conversion signal for temperature / voltage characteristic abnormality detection capable of accurately detecting the temperature / voltage characteristic, and the fixing control temperature / voltage conversion. A / D conversion means for switching the signal and the abnormality detection temperature / voltage conversion signal in a time-division manner to perform analog / digital conversion, and a temperature / voltage suitable for detecting a temperature near the fixing temperature by the voltage dividing resistance value switching means. The resistance value of the voltage-dividing resistor is switched so as to obtain a temperature / voltage conversion signal for fixing control having characteristics, and then the A / A
The temperature of the fixing unit is controlled to the fixing temperature by controlling the power supplied to the heater for heating the fixing unit so that the digital conversion value output from the D conversion unit becomes a predetermined value corresponding to the fixing temperature. And a temperature / temperature suitable for detecting a temperature near room temperature by the fixing temperature control means and the voltage dividing resistance value switching means.
When the digital conversion value output from the A / D conversion means is an abnormal value as room temperature after switching the resistance value of the voltage dividing resistor so as to be a temperature / voltage conversion signal for voltage characteristic abnormality detection. And a temperature detection abnormality detecting means for determining an abnormality in temperature detection by the thermistor and performing an abnormality handling process. 【請求項４】 定着器を加熱するヒータへの供給電力を
制御することにより前記定着器の温度を定着温度に制御
する定着器の温度制御装置の制御方法において、 前記定着器の温度変化に応じてその抵抗値が変化するサ
ーミスタと、前記サーミスタに直列接続され抵抗値が可
変に構成された分圧抵抗器と、前記サーミスタと前記分
圧抵抗器とを直列接続して構成される合成抵抗の両端に
所定の電圧を印加してその接続点から得られる温度／電
圧変換信号が、前記定着温度付近の温度を精度よく検出
できる温度／電圧特性の定着制御用温度／電圧変換信
号、または、室温付近の温度を精度よく検出できる温度
／電圧特性の異常検出用温度／電圧変換信号になるよう
前記分圧抵抗器の抵抗値を切り換える分圧抵抗値切換手
段と、前記定着制御用温度／電圧変換信号及び前記異常
検出用温度／電圧変換信号を時分割で切り換えてアナロ
グ／デジタル変換するＡ／Ｄ変換手段とを有し、前記分
圧抵抗値切換手段により前記定着温度付近の温度検出に
適した温度／電圧特性の定着制御用温度／電圧変換信号
になるよう前記分圧抵抗器の抵抗値を切り換えた上で前
記Ａ／Ｄ変換手段から出力されるデジタル変換値が、前
記定着温度に対応した所定の値になるよう前記定着器を
加熱するヒータへの供給電力を制御して前記定着器の温
度を前記定着温度に制御する一方、前記分圧抵抗値切換
手段により室温付近の温度検出に適した温度／電圧特性
の異常検出用温度／電圧変換信号になるよう前記分圧抵
抗器の抵抗値を切り換えた上で前記Ａ／Ｄ変換手段から
出力されるデジタル変換値が室温としては異常な値であ
る場合に、前記サーミスタによる温度検出の異常と判定
し異常対応処理を行うことを特徴とする定着器の温度制
御装置の制御方法。4. A control method of a temperature control device of a fixing device for controlling a temperature of the fixing device to a fixing temperature by controlling a power supplied to a heater for heating the fixing device, the method comprising: The thermistor having a variable resistance value, a voltage-dividing resistor connected in series to the thermistor and having a variable resistance value, and a combined resistor formed by connecting the thermistor and the voltage-dividing resistor in series. A temperature / voltage conversion signal obtained from a connection point by applying a predetermined voltage to both ends is a temperature / voltage conversion signal for fixing control having a temperature / voltage characteristic capable of accurately detecting a temperature near the fixing temperature, or room temperature. Voltage dividing resistance value switching means for switching the resistance value of the voltage dividing resistor so as to be a temperature / voltage conversion signal for temperature / voltage characteristic abnormality detection capable of accurately detecting a nearby temperature; and the fixing control temperature. A / D conversion means for switching the voltage conversion signal and the abnormality detection temperature / voltage conversion signal in a time-division manner to perform analog / digital conversion, and the voltage-dividing resistance switching means detects a temperature near the fixing temperature. After the resistance value of the voltage-dividing resistor is switched so as to obtain a fixing control temperature / voltage conversion signal having suitable temperature / voltage characteristics, the digital conversion value output from the A / D conversion means is adjusted to the fixing temperature. The temperature of the fixing device is controlled to the fixing temperature by controlling the power supplied to the heater for heating the fixing device so as to have a corresponding predetermined value, while the temperature near the room temperature is detected by the voltage dividing resistance switching means. After the resistance value of the voltage dividing resistor is switched so as to obtain a temperature / voltage conversion signal for detecting an abnormality in temperature / voltage characteristics suitable for the temperature, the digital conversion value output from the A / D conversion means is abnormal at room temperature. And determining whether the temperature is abnormal by the thermistor and performing an abnormality handling process when the value is a reasonable value. 【請求項５】 前記温度検出異常検出手段は、前記分圧
抵抗値切換手段により前記定着温度付近の温度検出に適
した温度／電圧特性の定着制御用温度／電圧変換信号に
なるよう前記分圧抵抗器の抵抗値を切り換えた上で前記
定着制御用Ａ／Ｄ変換手段から出力されるデジタル変換
値が、所定の下限値以下の場合にのみ、前記分圧抵抗値
切換手段により室温付近の温度検出に適した温度／電圧
特性の異常検出用温度／電圧変換信号になるよう前記分
圧抵抗器の抵抗値を切り換えて、前記異常検出用Ａ／Ｄ
変換手段から出力されるデジタル変換値が室温としては
異常な値である場合に、温度検出異常と判定し異常対応
処理を行うことを特徴とする請求項１に記載の定着器の
温度制御装置。5. The temperature detecting abnormality detecting means, wherein the voltage dividing resistance value switching means provides a voltage / voltage conversion signal for fixing control having a temperature / voltage characteristic suitable for detecting a temperature near the fixing temperature. Only when the digital conversion value output from the A / D conversion means for fixing control after switching the resistance value of the resistor is equal to or less than a predetermined lower limit value, the voltage dividing resistance value changing means changes the temperature around room temperature. The resistance value of the voltage-dividing resistor is switched so as to obtain a temperature / voltage conversion signal for temperature / voltage characteristics abnormality detection suitable for detection, and the abnormality detection A / D
2. The temperature control device for a fixing device according to claim 1, wherein when the digital conversion value output from the conversion unit is an abnormal value as room temperature, it is determined that the temperature detection is abnormal and an abnormality handling process is performed. 【請求項６】 前記前記分圧抵抗値切換手段により前記
定着温度付近の温度検出に適した温度／電圧特性の定着
制御用温度／電圧変換信号になるよう前記分圧抵抗器の
抵抗値を切り換えた上で前記定着制御用Ａ／Ｄ変換手段
から出力されるデジタル変換値が、所定の下限値以下の
場合にのみ、前記分圧抵抗値切換手段により室温付近の
温度検出に適した温度／電圧特性の異常検出用温度／電
圧変換信号になるよう前記分圧抵抗器の抵抗値を切り換
えて、前記異常検出用Ａ／Ｄ変換手段から出力されるデ
ジタル変換値が室温としては異常な値である場合に、温
度検出異常と判定し異常対応処理を行うことを特徴とす
る請求項２に記載の定着器の温度制御装置の制御方法。6. The resistance value of the voltage dividing resistor is switched by the voltage dividing resistance value switching means so that a temperature / voltage conversion signal for fixing control having a temperature / voltage characteristic suitable for temperature detection near the fixing temperature is obtained. Only when the digital conversion value output from the fixing control A / D conversion means is equal to or less than a predetermined lower limit value, the temperature / voltage suitable for detecting a temperature around room temperature by the voltage dividing resistance value switching means. The resistance value of the voltage-dividing resistor is switched so as to be a temperature / voltage conversion signal for characteristic abnormality detection, and the digital conversion value output from the abnormality detection A / D conversion means is an abnormal value as room temperature. 3. The method according to claim 2, wherein in the case, the temperature detection is determined to be abnormal and an abnormality handling process is performed. 【請求項７】 前記温度検出異常検出手段は、前記分圧
抵抗値切換手段により前記定着温度付近の温度検出に適
した温度／電圧特性の定着制御用温度／電圧変換信号に
なるよう前記分圧抵抗器の抵抗値を切り換えた上で前記
Ａ／Ｄ変換手段から出力されるデジタル変換値が、所定
の下限値以下の場合にのみ、前記分圧抵抗値切換手段に
より室温付近の温度検出に適した温度／電圧特性の異常
検出用温度／電圧変換信号になるよう前記分圧抵抗器の
抵抗値を切り換えて、前記Ａ／Ｄ変換手段から出力され
るデジタル変換値が室温としては異常な値である場合
に、温度検出異常と判定し異常対応処理を行うことを特
徴とする請求項３に記載の定着器の温度制御装置。7. The temperature detecting abnormality detecting means, wherein the voltage dividing resistance value switching means provides a voltage / voltage conversion signal for fixing control having a temperature / voltage characteristic suitable for detecting a temperature near the fixing temperature. Only when the digital conversion value output from the A / D conversion means after switching the resistance value of the resistor is equal to or less than a predetermined lower limit value, the voltage dividing resistance value switching means is suitable for detecting a temperature near room temperature. The resistance value of the voltage-dividing resistor is switched so as to obtain a temperature / voltage conversion signal for detecting abnormalities in the temperature / voltage characteristics, and the digital conversion value output from the A / D conversion means is an abnormal value for room temperature. 4. The temperature control device for a fixing device according to claim 3, wherein in a certain case, it is determined that the temperature detection is abnormal and an abnormality handling process is performed. 【請求項８】 前記分圧抵抗値切換手段により前記定着
温度付近の温度検出に適した温度／電圧特性の定着制御
用温度／電圧変換信号になるよう前記分圧抵抗器の抵抗
値を切り換えた上で前記Ａ／Ｄ変換手段から出力される
デジタル変換値が、所定の下限値以下の場合にのみ、前
記分圧抵抗値切換手段により室温付近の温度検出に適し
た温度／電圧特性の異常検出用温度／電圧変換信号にな
るよう前記分圧抵抗器の抵抗値を切り換えて、前記Ａ／
Ｄ変換手段から出力されるデジタル変換値が室温として
は異常な値である場合に、温度検出異常と判定し異常対
応処理を行うことを特徴とする請求項４に記載の定着器
の温度制御装置の制御方法。8. The resistance value of the voltage-dividing resistor is switched by the voltage-dividing resistance value switching means so as to obtain a temperature / voltage conversion signal for fixing control having a temperature / voltage characteristic suitable for detecting a temperature near the fixing temperature. Only when the digital conversion value output from the A / D conversion means is equal to or less than a predetermined lower limit value, is the temperature / voltage characteristic abnormality suitable for temperature detection near room temperature detected by the voltage dividing resistance value switching means. The resistance value of the voltage-dividing resistor is switched so as to obtain a temperature / voltage conversion signal for the A / A conversion.
5. The temperature control device for a fixing device according to claim 4, wherein when the digital conversion value output from the D conversion unit is an abnormal value as the room temperature, it is determined that the temperature detection is abnormal and an abnormality handling process is performed. Control method.