Canon Kabushiki Kaisha

Takao Kawazu

Atsuya Takahashi

Teruhiko Namiki

Nozomu Nakajima

Yusuke Nakashima

Tetsuya Yamamoto

Hiroshi Mano

Atsushi Iwasaki

Minoru Hayasaki

Ryota Ogura

Shigeo Murayama

Hideyuki Matsubara

Yasuhiro Nakata

Hiroshi Chihara

Kazunari Nishimoto

Takaomi Uezono

Masaki Inagaki

Toshiyuki Ichino

Yuji Fujiwara

A metal frame provides a ground potential. An image forming unit forms a toner image on a sheet. A fixing apparatus fixes the toner image on the sheet. The fixing apparatus comprises a heating element for generating heat by being supplied with power from an alternating current power source. An insulating layer covers the heating element. A conductive layer contacts the insulating layer and insulated from the metal frame. A tube-shaped member is heated by the heating element. A pressing member is arranged opposing the tube-shaped member and forms a nip portion in cooperation with the tube-shaped member. A capacitive element whose one end is connected to the metal frame and whose other end is connected to the conductive layer of the fixing apparatus.

Structure for electrically protecting fixing apparatus provided in image forming apparatus

A heater for use in an image heating apparatus includes a substrate, first and second conductors provided on the substrate, and heating elements. The heating elements are arranged between, and electrically connected in parallel to, the first and second conductors. When n denotes a number of heating elements, connected to one second conductor, in one row of the heating elements, a width L denotes a sum (n×Wh) of widths, as seen in a longitudinal direction of the substrate, of shortest current paths of all respective heating elements connected to the one second conductor plus a sum of widths, as seen in the longitudinal direction, of respective gaps between adjacent shortest current paths, and a ratio R denotes a ratio of the sum (n×Wh) of widths to the width L, the heating elements are configured so as to satisfy 0.54≤the ratio R<1.

Heater and image heating apparatus

A plurality of electric conductors provided on a substrate of a heater of an image heating device has a conductor group A including a plurality of first electric conductors and a conductor group B including a plurality of second electric conductors. The plurality of first electric conductors each have a first portion having a width W1 and a second portion having a width W2 smaller than the width W1, are provided on the substrate to be arranged side by side in a width direction. The plurality of second electric conductors each have a width W3 larger than the width W2, are provided on the substrate to be arranged side by side in a width direction so as to partially overlap the second portion.

Image heating device with first and second groups of conductors having different widths, and image forming apparatus

A triac driving circuit according to an embodiment of the present disclosure includes a phototriac coupler, a first resistive element, and a second resistive element, which are connected in series to a gate terminal of a triac. A minimum resistance of the first resistive element including tolerance is higher than a maximum resistance of the second resistive element including tolerance.

Triac driving circuit and fixing apparatus having resistive elements in series with different characteristics for circuit protection

The power supply apparatus includes a first power supply unit for outputting a first voltage; a second power supply unit for outputting a second voltage different from the first voltage; a switch unit operating with the first voltage, which is disposed in a power supply path connecting to the second power supply unit, for supplying and shutting down power to the second power supply unit; a detection unit for detecting that a predetermined voltage or higher is supplied to the first power supply unit; and a control unit for controlling the switch unit to stop the output of the first voltage from the first power supply unit, when the detection unit detects that the predetermined voltage or higher is supplied to the first power supply unit.

Power supply apparatus and image forming apparatus

The power supply apparatus includes a transformer having a primary and secondary sides, a first line and a second line to which an AC voltage is input from an AC power supply, a rectifying and smoothing unit that rectifies and smoothes the AC voltage, a shut-off unit provided between the first line and the rectifying and smoothing unit, a switching element that switches a current from the rectifying and smoothing unit to the primary side of the transformer, a first overvoltage detection unit that outputs a voltage corresponding to the AC voltage, a second overvoltage detection unit that outputs an overvoltage detection signal; and a control unit that controls the shut-off unit to shut off the input of the AC voltage.

Low power consumption accurate power supply overvoltage detection

An image heating apparatus includes first and second heat generating elements, first and second driving elements provided in a passage from a commercial power source to the heat generating elements, respectively, and a portion controlling the driving elements at a control level depending on a detection temperature. At the control level, a renewing period is two cycles of a waveform of an alternating current of the power source or an integral multiple thereof. The control portion controls, during a period when the control portion controls the driving elements at one control level, the driving elements so that the heat generating element to which the power is to be preferentially supplied is switched from the first to the second driving element and the waveform of the alternating current passing through each of the heat generating elements keeps symmetry of positive and negative half-cycle components with respect to a zero-voltage line.

Image heating apparatus

Image forming apparatus and power supply unit thereof, for controlling conditions of power supply units according to input voltage

An image heating device includes a pressure-changing mechanism configured to change pressure applied to a heating nip. A cam of the pressure-changing mechanism acting on a pressure-applying mechanism is attached to a rotating shaft of a conveying roller that conveys recording materials. With this, an increase in the cost of the device can be regulated.

Image heating device capable of changing pressure applied to heating nip

A period of a first edge, a voltage change in a first direction of a first pulse signal fed from a zero-crossing detecting circuit, is detected. A second edge, a voltage change in a second direction opposite to the first direction, is generated when a time period equal to half the period of the first edge has elapsed from the next first edge. In response to a second pulse signal generated from the first and second edges, phase control of power to be supplied to heating elements is performed by using triacs. In this manner, during power control using a signal from the zero-crossing detecting circuit as a trigger signal, is achieved stable power control which enables tracking even though the power supply frequency fluctuates, and which is impervious to the effect of the positive or negative polarity of an input power supply.

Power supply apparatus and heating apparatus and image forming apparatus

This invention is intended to control the amount of power to be supplied to a fusing heater below a maximum applicable current value. The engine controller supplies electricity to both of two heating bodies at the same fixed duty D1. At a phase angle al corresponding to the fixed duty D1, pulse signals ON1 and ON2 are issued in response to a ZEROX signal as a trigger. A current value I1 is detected based on a HCRRT signal from the current detection circuit. The engine controller calculates an upper limit of applicable power duty Dlimit based on the detected current value I1, the fixed duty D1 and the preset applicable current value Ilimit. Then, a PI temperature control is performed at a duty below the upper-limit duty Dlimit.

Image fusing device with power control and image forming apparatus with same

This invention is intended to control the amount of power to be supplied to a fusing heater below a maximum applicable current value. The engine controller supplies electricity to both of two heating bodies at the same fixed duty DAt a phase angle &#x3b1;corresponding to the fixed duty Dpulse signals ONand ONare issued in response to a ZEROX signal as a trigger. A current value Iis detected based on a HCRRT signal from the current detection circuit. The engine controller calculates an upper limit of applicable power duty Dlimit based on the detected current value Ithe fixed duty Dand the preset applicable current value Ilimit. Then, a PI temperature control is performed at a duty below the upper limit duty Dlimit.

Image fusing device and image forming apparatus

This invention is intended to control the amount of power to be supplied to a fusing heater below a maximum applicable current value. The engine controller supplies electricity to both of two heating bodies at the same fixed duty D. At a phase angle &#x3b1;corresponding to the fixed duty D, pulse signals ONand ONare issued in response to a ZEROX signal as a trigger. A current value Iis detected based on a HCRRT signal from the current detection circuit. The engine controller calculates an upper limit of applicable power duty Dlimit based on the detected current value I, the fixed duty Dand the preset applicable current value Ilimit. Then, a PI temperature control is performed at a duty below the upper limit duty Dlimit.

A thermostatic device has a temperature detecting portion for detecting temperature, the portion including a bimetal and a heat conductive cap for covering the bimetal, and an opening/closing portion for opening and closing electric contact point in accordance with an operation of the temperature detecting portion, and the opening/closing portion is extended long, and a length of the opening/closing portion in the longitudinal direction is greater than a length of the heat conductive cap in the same longitudinal direction.

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Susono, Japan

Takao Kawazu