Electric heating – Heating devices – Combined with diverse-type art device
Reexamination Certificate
2000-02-25
2001-08-14
Pelham, Joseph (Department: 3742)
Electric heating
Heating devices
Combined with diverse-type art device
C219S469000, C399S165000, C198S808000, C198S816000
Reexamination Certificate
active
06274846
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a belt conveying apparatus in which a belt entrained about a plurality of rollers is rotated by receiving a rotational driving force imparted by at least one driving roller, and to an image forming apparatus in which a photosensitive material and an image receiving material are superposed on each other and heat developed in a heat developing processing section of the apparatus.
2. Description of the Related Art
An image forming apparatus is proposed which records an image on a photosensitive material, carries out thermal developing processing in a state in which the photosensitive material having an image recorded thereon and an image receiving material are superimposed, and transfers the image to an image receiving material.
In the thermal developing processing, the two sheet materials, which are formed by laminating the photosensitive material and the image receiving material in the presence of an image forming solvent (for example, water), are wound about the circumferential surface of a heating drum, and are then conveyed while being held by a belt. The heating drum is provided with a halogen lamp, as a heating source, in a shaft core thereof. Heat generated when the halogen lamp is lit heats the circumferential surface of the heating drum. The photosensitive material and the image receiving material undergoes thermal development transfer processing due to this heat, so that an image on the photosensitive material is transferred to the image receiving material.
The belt is entrained about a plurality of rollers. One roller among the plurality of rollers is a driving roller. The belt circles about the plurality of rollers in synchronism with rotational speed of the heating drum, due to rotational driving force of the driving roller. The problem of the belt moving sideways as it is conveyed about the plurality of rollers cannot be ignored. The image forming apparatus is for originals of a comparatively large size (for example, 841 mm×1189 mm, or 728 mm×1030 mm) and width of the belt has become larger in accordance with the size of the original. The amount the belt moves sideways during conveyance increases as the transverse dimension of the belt increases. This sideways movement is caused by the flatness of the circumferential surface of the rollers about which the belt is entrained (the rollers have the same radius throughout in the axial direction).
As a result, it has been proposed to make each of the driven rollers, which are the rollers other than the driving roller, in a trapezoidal form, by tapering a portion in a vicinity of both ends in the axial direction thereof (for an example, refer to Japanese Patent Application Laid-Open (JP-A) No. 2-66036). Due to this structure, the belt that moves sideways onto the tapered portions increases in speed, since the tapered portions have an increased linear speed due to an increased diameter. As a result, the belt returns to its original position. Accordingly, sideways movement is prevented from worsening.
However, with the above-described prior art, since the tapered portions and the driven roller that is the base body for the tapered portions rotate integrally, the force apt to move the belt sideways and the force apt to reverse the sideways movement may balance each other. As a result, even if sustained sideways movement is not caused, the belt moves in the transverse direction at certain positions, which causes the photosensitive material and the image receiving material to become out of registration. At this time, uneven transfer occurs, which reduces image quality.
In the prior art, there is disclosed a technology wherein, in cases where sideways movement occurs, positions of both ends of some of the driven rollers are independently adjusted in the axial direction. Namely, by inclining the axial line of the driven roller in the direction opposite to the direction of the sideways movement, the sideways movement can be reversed.
However, since the direction of inclination is also inclined such that the axial line is inclined in the direction the belt is conveyed, excessive torsion takes place and the belt may form slack. Due to this slack, force holding the photosensitive material and the image receiving material varies across the transverse direction thereof, and uneven transfer may occur as a result.
SUMMARY OF THE INVENTION
In light of the above-described circumstances, an object of the present invention is to achieve a belt conveying apparatus wherein, when the belt moves sideways, the belt can be returned to its original position easily.
Another object of the present invention is to achieve a belt conveying apparatus that can inhibit sideways movement by setting inclination of a driven roller so as to prevent the belt from moving sideways.
Still another object of the present invention is to achieve a belt conveying apparatus in which, in cases where an image on an photosensitive material is transferred to an image receiving material by heating the photosensitive material and the image receiving material in a state in which they are laminated together, reduction of image quality can be inhibited by preventing uneven transfer caused by the belt moving sideways.
A first aspect of the present invention is a belt conveying apparatus for rotating a belt entrained on a plurality of rollers, comprising: at least one driving roller among the plurality of rollers, for imparting rotational driving force to the belt; at least one driven roller among the plurality of rollers, which does not impart rotational driving force to the belt; auxiliary rollers attached to the at least one driven roller, which driven roller is a base body thereof, so as to be able to undergo rotation relative to the driven roller, the diameter of each of the auxiliary rollers gradually increasing from an end portion of the auxiliary roller at an end portion of the driven roller towards the other end portion of the auxiliary roller in the axial direction.
According to the first aspect, the auxiliary roller is provided at each of two ends of the driven roller in the axial direction. The auxiliary roller is in a tapered from and rotates relatively to the driven roller, which is the base body of the auxiliary roller. Accordingly, the auxiliary roller is rotated by the conveying force of the belt when the belt reaches the auxiliary roller (namely, when the belt moves sideways). At this time, since the auxiliary roller is in the in the tapered form, linear speeds of portions in the axial direction differ from each other. The closer to the outer side of the auxiliary roller, the faster the linear speed of the roller. Therefore, the belt is easily returned to its original position. Namely, the auxiliary roller rotates irrespective of rotation of the driven roller that is the base body thereof and rotates only by conveying force of the belt. Accordingly, the drawback in which the force moving the belt sideways and the force returning the belt to its original position equally balance each other such that the belt is maintained in a displaced state is avoided.
A second aspect of the present invention is a belt conveying apparatus for rotating a belt entrained on a plurality of rollers, comprising: at least one driving roller among the plurality of rollers, for imparting rotational driving force to the belt; at least one driven roller among the plurality of rollers, which does not impart rotational driving force to the belt; a driven roller-miving mechanism, which allows two end portions of the driven roller in the axial direction to move independently from each other in a direction perpendicular to a rotational axis of the driven roller and along a line connecting a center point of a wound dimension of the belt wound on the driven roller and the rotational axis of the driven roller; and a positioning—and fixing-mechanism, for positioning and fixing beforehand both end portions of the belt in the axial direction at respedtive positions at which sideways movement of the be
Ono Tsukasa
Tomimizu Masaaki
Fuji Photo Film Co. , Ltd.
Pelham Joseph
Sughrue Mion Zinn Macpeak & Seas, PLLC
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