Abstract: A fixing device has a heating rotor, a pressure belt, a sheet member, first and second pressurizing members, a motor and a control unit. The control unit controls the motor to rotate the heating rotor and the pressure belt in a direction opposite to a conveyance direction of a recording material at startup time after jam treatment of the recording material. Contact positions of the sheet member with respect to the first and second pressurizing members are changed, so that the sheet member is prevented from obstructing independent actions of each of the first and second pressurizing members, which allows the nip portion N to maintain proper nip width and proper nip pressure. Thus, the fixing device has excellent stability at the nip portion to improve fixability and conveyability of the recording material with a simple construction.

Abstract: A belt-nip system fixing apparatus reduces the frequency of replacing a pressure belt or a sliding sheet. In accordance with a sheet measurement in a roller axis direction, the fixing apparatus switches a pressure distribution in the roller axis direction between a low-pressure load distribution in which pressure is greatest at a center pressure switching projection of a hard pad, and pressure gradually lessens towards pressure switching projections near the ends of the hard pad, and the pressure in a range of 216 [mm] in a center in the roller axis direction is greater than or equal to a necessary pressure for fixing (a predetermined value Nm) while the pressure in other projections near the ends is below the predetermined value Nm, and a high-pressure load distribution in which the pressure throughout the total area in the roller axis direction equals or exceeds the predetermined value Nm.

Abstract: A belt-nip system fixing apparatus or an image formation apparatus including the fixing apparatus reduces the frequency of replacing a pressure belt or a sliding sheet. In accordance with a sheet measurement in a roller axis direction, the fixing apparatus or image formation apparatus switches a pressure distribution in the roller axis direction between a low-pressure load distribution in which pressure is greatest at a center pressure switching projection (542b) of a hard pad (542), and pressure gradually lessens towards pressure switching projections (543c) near the ends of the hard pad (542), and the pressure in a range of 216 [mm] in a center in the roller axis direction is greater than or equal to a necessary pressure for fixing (a predetermined value Nm) while the pressure in other projections near the ends is below the predetermined value Nm, and a high-pressure load distribution in which the pressure throughout the total area in the roller axis direction equals or exceeds the predetermined value Nm.

Abstract: To realize a mixer with a charge subsampling circuit with which a base band signal can be readily obtained without being affected by noise from wide bandwidth signals or undesired signals. A current generating circuit 8 outputs a current in proportion to the input signal voltage. In response to a control signal from the timing generating block 6, a charge subsampling circuit 7 samples the current at the same sampling frequency as the carrier frequency. In a charge-integrating process accompanying the sampling, weighting is carried out on terms in the transfer function of the FIR filter using a set of selected weights.

Abstract: The ?? AD converter includes: a sampling section for sampling an input signal at each cycle Ts; an AD conversion section for performing AD conversion of the input signal; a DA conversion section for performing DA conversion of an output of the AD conversion section; and a loop filter for integrating a difference obtained by subtracting an output of the DA conversion section from an output of the sampling section so as to output the integrated difference to the AD conversion section, wherein the sampling section includes two sampling circuits disposed parallel to each other, and the two sampling circuits respectively operate at timings different from each other, and each of the sampling circuits delays the input signal so as to output the delayed input signal.

Abstract: A fixing device has a heating rotor, a pressure belt, a sheet member, first and second pressurizing members, a motor and a control unit. The control unit controls the motor to rotate the heating rotor and the pressure belt in a direction opposite to a conveyance direction of a recording material at startup time after jam treatment of the recording material. Contact positions of the sheet member with respect to the first and second pressurizing members are changed, so that the sheet member is prevented from obstructing independent actions of each of the first and second pressurizing members, which allows the nip portion N to maintain proper nip width and proper nip pressure. Thus, the fixing device has excellent stability at the nip portion to improve fixability and conveyability of the recording material with a simple construction.

Abstract: A fixing device has a fixing belt, a trembler coil for heating the fixing belt with magnetic flux, a ferrite core around which the trembler coil is wound, and a heater for heating the ferrite core. The ferrite core has a Curie temperature which is between a fixing temperature of the fixing belt and a smoking start temperature of the fixing belt. The heating of the ferrite core with the heater allows the temperature of the ferrite core to reach the Curie temperature before the temperature of the fixing belt reaches a smoking start temperature. Thereby, an excessive rise in temperature of the fixing belt is suppressed, which prevents the fixing belt from smoking and igniting.

Abstract: A Fixing device has a heat roller, a magnetic flux generating element, and a magnetic flux block section. The magnetic flux block section for blocking magnetic flux flowing from a magnetic flux generating element to a heat roller is moved to a position at which the magnetic flux does not cause the heat roller to generate heat when rotation of the heat roller stops. The magnetic flux block section is moved to a position at which the heat roller generates heat when the heat roller rotates. Therefore, when rotation of the heat roller stops, even if electric current is applied to the magnetic flux generating element to generate magnetic flux from the magnetic flux generating element, heat generation by the magnetic flux generating element is prevented, so that smoking and firing of the heating element is suppressed.

Abstract: A loop delay control circuit is provided between a comparator and a power switch stage. When the amplitude of an input signal is especially high, the loop delay control circuit secures an oscillation threshold value by setting a delay amount at a low value. On the other hand, when the amplitude of the input signal is not so high, the loop delay control circuit reduces an average switching rate by increasing the delay amount, but does not reduce the oscillation threshold value. This makes it possible to provide a delta-sigma modulator allowing realization of both (i) a high oscillation threshold value, i.e., high output power, and (ii) high power efficiency.

Abstract: The ?? AD converter includes: a sampling section for sampling an input signal at each cycle Ts; an AD conversion section for performing AD conversion of the input signal; a DA conversion section for performing DA conversion of an output of the AD conversion section; and a loop filter for integrating a difference obtained by subtracting an output of the DA conversion section from an output of the sampling section so as to output the integrated difference to the AD conversion section, wherein the sampling section includes two sampling circuits disposed parallel to each other, and the two sampling circuits respectively operate at timings different from each other, and each of the sampling circuits delays the input signal so as to output the delayed input signal.

Abstract: A loop delay control circuit is provided between a comparator and a power switch stage. When the amplitude of an input signal is especially high, the loop delay control circuit secures an oscillation threshold value by setting a delay amount at a low value. On the other hand, when the amplitude of the input signal is not so high, the loop delay control circuit reduces an average switching rate by increasing the delay amount, but does not reduce the oscillation threshold value. This makes it possible to provide a delta-sigma modulator allowing realization of both (i) a high oscillation threshold value, i.e., high output power, and (ii) high power efficiency.

Abstract: To realize a mixer with a charge subsampling circuit with which a base band signal can be readily obtained without being affected by noise from wide bandwidth signals or undesired signals. A current generating circuit 8 outputs a current in proportion to the input signal voltage. In response to a control signal from the timing generating block 6, a charge subsampling circuit 7 samples the current at the same sampling frequency as the carrier frequency. In a charge-integrating process accompanying the sampling, weighting is carried out on terms in the transfer function of the FIR filter using a set of selected weights.

Abstract: A fixing device has a fixing belt, a trembler coil for heating the fixing belt with magnetic flux, a ferrite core around which the trembler coil is wound, and a heater for heating the ferrite core. The ferrite core has a Curie temperature which is between a fixing temperature of the fixing belt and a smoking start temperature of the fixing belt. The heating of the ferrite core with the heater allows the temperature of the ferrite core to reach the Curie temperature before the temperature of the fixing belt reaches a smoking start temperature. Thereby, an excessive rise in temperature of the fixing belt is suppressed, which prevents the fixing belt from smoking and igniting.

Abstract: In the hold phase, two negative feedback circuits constituted by the negative feedback capacitors 6p and 6m and two positive feedback circuits constituted by positive feedback capacitors are provided between an input terminal and an output terminal of an operational amplifier. Here, in a sampling phase before a hold phase, charges according an input signal V1p is stored in each of the capacitors, and charges according to an input signal V1p are stored in each of the capacitors. As a result, a gain of the switched capacitor amplifier circuit is derived from (Ca+C)/(Ca?Cx) wherein Ca indicates an electrostatic capacitance of the negative feedback capacitors, and Cx indicates an electrostatic capacitance of the positive feedback capacitors, and thus the gain can be increased without significantly increasing an electrostatic capacitance ratio.

Abstract: In the hold phase, two negative feedback circuits constituted by the negative feedback capacitors 6p and 6m and two positive feedback circuits constituted by positive feedback capacitors are provided between an input terminal and an output terminal of an operational amplifier. Here, in a sampling phase before a hold phase, charges according an input signal V1p is stored in each of the capacitors, and charges according to an input signal V1p are stored in each of the capacitors. As a result, a gain of the switched capacitor amplifier circuit is derived from (Ca+C)/(Ca?Cx) wherein Ca indicates an electrostatic capacitance of the negative feedback capacitors, and Cx indicates an electrostatic capacitance of the positive feedback capacitors, and thus the gain can be increased without significantly increasing an electrostatic capacitance ratio.

Abstract: In the hold phase, two negative feedback circuits constituted by the negative feedback capacitors 6p and 6m and two positive feedback circuits constituted by positive feedback capacitors are provided between an input terminal and an output terminal of an operational amplifier. Here, in a sampling phase before a hold phase, charges according an input signal V1p is stored in each of the capacitors, and charges according to an input signal V1p are stored in each of the capacitors. As a result, a gain of the switched capacitor amplifier circuit is derived from (Ca+C)/(Ca?Cx) wherein Ca indicates an electrostatic capacitance of the negative feedback capacitors, and Cx indicates an electrostatic capacitance of the positive feedback capacitors, and thus the gain can be increased without significantly increasing an electrostatic capacitance ratio.

Abstract: A non-inverting-side first switch is formed in a first area on one of sides of a differential amplifier, meanwhile a non-inverting-side second switch is formed in a second area on the other of sides of the differential amplifier, the non-inverting switches being for resetting a non-inverting input terminal of the differential amplifier. Similarly, An inverting-side first switch is formed in the first area, meanwhile an inverting-side second switch is formed in the second area, the inverting switches being for resetting a non-inverting input terminal of the differential amplifier. Further, a non-inverting-side line connecting the non-inverting-side first switch and the non-inverting input terminal, and an inverting-side line connecting the inverting-side first switch and the inverting-side second switch are provided next to each other. A signal line crossing one of the lines is provided so as to cross the other of the lines.

Abstract: A sample-and-hold amplifier circuit has a switch, provided between an operational amplifier stage and an inverting amplifier stage, for connecting or cutting off the connection of the operational amplifier stage and the inverting amplifier stage. During the first operation phase (&phgr;1), the first and second switches are switched to the &phgr;1 side, the third switch is conductive, and the switch for connecting or cutting off the connection is nonconductive. Thus, sampling can be carried out so that first and second capacitors are charged by predetermined electrical charges. During the second operation phase (&phgr;2), the first and second switches are switched to the &phgr;2 side, the third switch is nonconductive, and the switch for connecting or cutting off the connection is conductive.

Abstract: A non-inverting-side first switch is formed in a first area on one of sides of a differential amplifier, meanwhile a non-inverting-side second switch is formed in a second area on the other of sides of the differential amplifier, the non-inverting switches being for resetting a non-inverting input terminal of the differential amplifier. Similarly, An inverting-side first switch is formed in the first area, meanwhile an inverting-side second switch is formed in the second area, the inverting switches being for resetting a non-inverting input terminal of the differential amplifier. Further, a non-inverting-side line connecting the non-inverting-side first switch and the non-inverting input terminal, and an inverting-side line connecting the inverting-side first switch and the inverting-side second switch are provided next to each other. A signal line crossing one of the lines is provided so as to cross the other of the lines.

Abstract: A sample-and-hold amplifier circuit of the present invention has a switch, provided between an operational amplifier stage and an inverting amplifier stage, for connecting or cutting off the connection of the operational amplifier stage and the inverting amplifier stage. During the first operation phase (&phgr;1), the first and second switches are switched to the &phgr;1 side, the third switch is conductive, and the switch for connecting or cutting off the connection is nonconductive. This allows to carry out the sampling so that the first and second capacitors are charged by predetermined electrical charges. During the second operation phase (&phgr;2), the first and second switches are switched to the &phgr;2 side, the third switch is nonconductive, and the switch for connecting or cutting off the connection is conductive. This allows that the voltage thus sampled is subjected to the operational amplification.