Abstract: A fixing apparatus can prevent an excessive rise in temperature of a paper non-passage area due to diverted flow of magnetic flux from a paper passage area of a heat-producing element to a paper non-passage area thereof has a small configuration. A center core is rotated by a rotation section, bringing cutaway parts to a magnetic path masking position, and the degree of magnetic coupling between the center core and a heat-producing roller is weakened, suppressing an excessive rise in temperature of paper non-passage areas of the heat-producing roller. With this fixing apparatus, switching of the intensity of magnetic coupling between the center core and heat-producing roller can be performed simply by rotating the center core. Also, with this fixing apparatus, it is not necessary for magnetism suppressing elements to be provided as separate members, enabling the configuration to be made simpler and less expensive.

Abstract: An electromagnetic induced heating roller comprises a core member, an elastic layer, induction heating layer, and a mold release layer in this order from inside to outside. Further, a magnetic shield layer for preventing a magnetic flux from penetrating into the core member is interposed between the induction heating layer and the core member. The production of an alternating magnetic field from a magnetic field generating device, a leakage flux having penetrated through the induction heating layer is trapped by the magnetic shield layer. As a result, most of the impressed alternating magnetic flux is consumed for heating the heating layer, resulting in an improvement in the heating efficiency. A trouble is prevented which is generated by heating the bearing of the core member.

Abstract: A heating apparatus that enables an abnormally high temperature detection section that detects, when a heating element heated by means of electromagnetic induction reaches an abnormally high temperature, this abnormally high temperature, to operate speedily and reliably irrespective of the material and temperature characteristic of the heating element in a low-cost and compact configuration. In this apparatus, thermostat 301 is disposed on the same side as exciting coil 231 with respect to heat generating belt 210 and between winding bundles of a conductor wire of exciting coil 231. This allows coil guide 234 to hold both thermostat 301 and exciting coil 231 and allows these wires and terminals to be concentrated on one location, thus making it possible to reduce the number of parts and assembling man-hours and configure the body of the apparatus in a low-cost and compact configuration.

Abstract: A fixing apparatus can prevent an excessive rise in temperature of a paper non-passage area due to diverted flow of magnetic flux from a paper passage area of a heat-producing element to a paper non-passage area thereof has a small configuration, A center core is rotated by a rotation section, bringing cutaway parts to a magnetic path masking position, and the degree of magnetic coupling between the center core and a heat-producing roller is weakened, suppressing an excessive rise in temperature of paper non-passage areas of the heat-producing roller. With this fixing apparatus, switching of the intensity of magnetic coupling between the center core and heat-producing roller can be performed simply by rotating the center core. Also, with this fixing apparatus, it is not necessary for magnetism suppressing elements to be provided as separate members, enabling the configuration to be made simpler and less expensive.

Abstract: In a fixing apparatus using an induction heating type of heating apparatus, there are provided an excitation apparatus that generates magnetic flux, an opposed core located opposite the excitation apparatus, a fixing belt that is induction-heated by the aforementioned magnetic flux, and magnetism masking elements that block magnetic paths corresponding to paper non-passage areas of fixing belt between the excitation apparatus and the opposed core. By blocking magnetic paths between the excitation apparatus and the opposed core by the magnetism masking elements, magnetic flux that induction-heats the fixing belt is effectively masked, and an excessive rise in temperature of paper non-passage areas of fixing belt is prevented.

Abstract: In an optical scanning device using two polygon mirrors, the present invention achieves both a simplification of the device and a reduction of vibrations. An optical scanning device is provided with a first optical system including a polygon mirror and a second optical system including a polygon mirror. The polygon mirror provided in the first optical system and the polygon mirror provided in the second optical system are configured such that they rotate in mutually opposite directions. Further, the optical scanning device is provided with one BD sensor for detecting laser beams that are scanned with the polygon mirrors. Slits with mutually different widths are arranged between the BD sensor and the respective polygon mirrors of the first and second optical systems.

Abstract: In an overfilled optical scanner in which a plurality of light beams are used, a uniform luminous-energy distribution is achieved on a scanning plane to be scanned. The optical scanner includes: a light source 3 for producing a first light beam L1 and a second light beam L2; a polygon mirror; a first image formation optical system for leading the light beams L1 and L2 to a deflecting plane of the polygon mirror and for forming, on the deflecting plane, a line image whose width is greater than the plane width of the deflecting plane; and a second image formation optical system for leading the light beams L1 and L2 from the polygon mirror to the scanning plane of a photosensitive drum and forming an image on the scanning plane. The first image formation optical system is adjusted so that the optical axes A1 and A2 of the first and second light beams L1 and L2 are approximately symmetrical about the optical axis A0 of the first image formation optical system.

Abstract: A heating roller (21) includes a heat generating layer (22) that generates heat by electromagnetic induction, a heat insulating layer (23), and a supporting layer (24), which are provided inwardly in this order. The supporting layer (24) is formed of a material having a specific resistance of 1×10?5 ?m or higher. Therefore, even when the heat generating layer (22) has a thickness smaller than a skin depth, i.e. a thickness defined by a flow of an induction current, so that magnetic flux penetrates the heat generating layer (22) and even reaches the supporting layer (24), heat generation of the supporting layer (24) under an eddy current can be suppressed. Thus, the heat generating layer (22) can be decreased in thermal capacity, and heat generation of the supporting layer (24) is suppressed, so that only the heat generating layer (22) can be heated efficiently. As a result, a warm-up time can be reduced. Further, breakage by heat of, for example, bearings supporting the heating roller (21) can be prevented.

Abstract: An image heating device according to an embodiment of the present invention includes a heat generator that has an outer surface and that generates heat by induction heating and a heater positioned close to the outer surface of the heat generator, the heater being configured to heat the heat generator by induction heating. A positioner is located close to an end of the heater, the positioner being configured to position the heater with respect to the heat generator. A vibration absorber is attached to the positioner and is configured, in one embodiment, to viscoelasticly absorb vibration of the heater produced by a vibration caused by an electromagnetic repulsive force acting between the heat generator and the heater when the heater heats the heat generator by induction heating.

Abstract: An image heating apparatus is provided that enables the entire width of a heat-producing medium to be heated uniformly and an excessive rise in temperature to be prevented, without making the configuration complex. In a fixing unit 19 in which this apparatus is applied, a fixing belt 112 is an annular member that has an inner peripheral surface and an outer peripheral surface, and produces heat through the action of magnetic flux. An exciting coil 120 is located in proximity to the outer peripheral surface of fixing belt 112, and generates magnetic flux that acts upon fixing belt 112. A suppression member 650 is located in proximity to inner peripheral surface of fixing belt 112, and reduces, of the magnetic flux generated by exciting coil 120, magnetic flux that acts upon a paper non-passage area of fixing belt 112.

Abstract: A fixing unit is provided with a fixing belt that heats recording paper that bears and moves a toner image, an exciting coil that generates magnetic flux in the fixing belt and causes the fixing belt to produce heat by electromagnetic induction, and a heat production adjustment section that adjusts the calorific value distribution of the fixing belt by adjusting the magnetic flux acting upon the fixing belt.

Abstract: In an optical scanning device using two polygon mirrors, the present invention achieves both a simplification of the device and a reduction of vibrations. An optical scanning device is provided with a first optical system including a polygon mirror and a second optical system including a polygon mirror. The polygon mirror provided in the first optical system and the polygon mirror provided in the second optical system are configured such that they rotate in mutually opposite directions. Further, the optical scanning device is provided with one BD sensor for detecting laser beams that are scanned with the polygon mirrors. Slits with mutually different widths are arranged between the BD sensor and the respective polygon mirrors of the first and second optical systems.

Abstract: A heat-fixing apparatus is provided that enables a rise in temperature of a heating member to be closely tracked, and an excessive rise in temperature of the heating member to be obviated, a simple configuration and irrespective of differences in the operating mode, such as immediately after a rise in temperature or during continuous operation. Different threshold values are set in accordance with different modes, such as a warm-up mode and a fixing operation mode. Threshold decisions on a switching frequency controlled by a frequency control section are made using different threshold values, according to the mode. A switching frequency of switching elements are varied so that power necessary in each mode is supplied to an exciting coil. An excessive rise in temperature is prevented in each mode by halting a switching element drive in accordance with the threshold decision.

Abstract: A heating roller (21) includes a heat generating layer (22) that generates heat by electromagnetic induction, a heat insulating layer (23), and a supporting layer (24), which are provided inwardly in this order. The heat generating layer (22) is composed of at least two layers that are a first heat generating layer of a magnetic material and a second heat generating layer of a non-magnetic material. The first heat generating layer has a specific resistance higher than a specific resistance of the second heat generating layer and a thickness larger than a thickness of the second heat generating layer. This allows the second heat generating layer to function effectively as a heat generating part that generates heat by electromagnetic induction. Thus, compared with the case where the heat generating layer (22) is formed only of a single layer of a magnetic material, heat generation efficiency is increased, thereby allowing warm-up time to be reduced.

Abstract: A temperature determining device is composed of a temperature detecting unit that detects a temperature of a determination object member based on an intensity of infrared rays from the object member, a unit for determining a temperature for correction that determines a temperature of an opposing member opposed to the object member or a temperature of a member whose temperature changes in correlation to a change in the temperature of the opposing member, and a calculating unit that corrects the detected temperature obtained by the temperature detecting unit using the temperature as the temperature for correction obtained by the unit for determining a temperature for correction. Thus, stable temperature determination can be performed accurately without being influenced by infrared rays from around a determination object member.

Abstract: An ultrasonic vibration tool is made of a block of substantially rectangular parallelepiped form, and has its one end face formed as an output end face, and has its other end face opposite the output end face formed as an input end face. An ultrasonic oscillator is connected to the input end face for transmitting a longitudinal standing wave to the output end face. Peripheries of the input and output end faces of the block constitute mass portions. Between the mass portions are formed slits at a pitch less than a half of an oscillation wavelength, whereby a plurality of elastic portions are obtained. The mass portion on the input end face side has a protrusion having a height equal to or less than a quarter of the oscillation wavelength, thereby obtaining a mass distribution. Hence, a uniform amplitude distribution is achieved in the output end face.

Abstract: An electromagnetic induced heating roller (21) comprises a core member (24), an elastic layer (23), induction heating layer (22), and a mold release layer in this order from inside to outside. Further, a magnetic shield layer for preventing a magnetic flux from penetrating into the core member (24) is interposed between the induction heating layer (22) and the core member (24). Out of an alternating magnetic field from a magnetic field generating means, a leakage flux having penetrated through the induction heating layer (22) is trapped by the magnetic shield layer. As a result, most of the impressed alternating magnetic flux is consumed for heating the heating layer (22), resulting in an improvement in the heating efficiency. A trouble is prevented which is generated by heating the bearing of the core member (24).

Abstract: A maximum likelihood encoding apparatus is provided, which is constructed to be compatible with a plurality of signals reproduced from a plurality of recording media having a plurality of types. The apparatus comprises a path metric value generation section for generating a plurality of path metric values corresponding to a recording medium having one of the plurality of types based on a type signal indicating the one of the plurality of types, and a path memory section for detecting digital information from a signal reproduced from the recording medium having the one of the plurality of types based on the plurality of path metric values.

Abstract: A reflector 10 is formed so as to have a long side along a scanning direction of a ray bundle. The reflector 10 includes a thin-plate-shaped reflector body having one plane to be a reflection plane 20 and upper and lower ribs 21a and 21b each extending from the reflector body in a back side. The reflector plane 20 is formed of a curved plane having positive power at least in the scanning direction, i.e., a so called free-form plane. The reflector 10 is supported by protrusions 31, 32 and 33 at three points, i.e., first, second and third support points S1, S2 and S3 located in the vicinities of one end portion of the reflector, the other end of thereof, and a center portion thereof, respectively. A distance L1 between an imaginary straight line V1 joining the first and second support points S1 and S2 and the third support point S3 is larger than a sag L2 of the reflector 20.

Abstract: In an overfilled optical scanner in which a plurality of light beams are used, a uniform luminous-energy distribution is achieved on a scanning plane to be scanned. The optical scanner includes: a light source 3 for producing a first light beam L1 and a second light beam L2; a polygon mirror; a first image formation optical system for leading the light beams L1 and L2 to a deflecting plane of the polygon mirror and for forming, on the deflecting plane, a line image whose width is greater than the plane width of the deflecting plane; and a second image formation optical system for leading the light beams L1 and L2 from the polygon mirror to the scanning plane of a photosensitive drum and forming an image on the scanning plane. The first image formation optical system is adjusted so that the optical axes A1 and A2 of the first and second light beams L1 and L2 are approximately symmetrical about the optical axis A0 of the first image formation optical system.