Heat protection of photosensitive elements in image formation apparatus

An image formation apparatus, comprising:

• a continuous form photosensitive member positioned to move along a predefined transfer path;
• exposure means disposed along said transfer path for exposing an image onto a portion of said photosensitive member;
• heat developing means disposed along said transfer path for heating said exposed image portion and for intercepting heat to an unexposed portion of said photosensitive member, said heat developing means comprising
• a cylindrical housing having (1) a heated portion arranged along a longitudinal axis of said cylindrical housing and having a heating element in surface contact with and for heating exposed portions of said photosensitive member, the longitudinal axis being positioned transverse to said transfer path and (2) an unheated portion arranged along the longitudinal axis of said cylindrical housing and separated from said heated portion by a thermally insulative material, and
• a thermal shield selectively movable along said transfer path in synchronization with and in the direction of transfer of said photosensitive member between at least one heat shielding position and one non-heat shielding position for protecting and preserving unexposed portions of said photosensitive member, said thermal shield comprising a curved heat shield positioned adjacent to said heating element and being movable concentric about said longitudinal axis between the heat shielding position between said heating element and said photosensitive member and the non-heat shielding position;
• and
• pressure transfer means for superposing, under pressure, said exposed image portion of said photosensitive member and an image transfer member.

An image formation apparatus comprising:

• exposure devices for exposing a photosensitive member having, on a supporting body, a microcapsule in which at least a photosensitive substance and a coloring material are sealed;
• a heat developing device for heating exposed image portions of said photosensitive member, said heat developing device comprising
• a cylindrical housing having (1) a heated portion arranged along a longitudinal axis of said cylindrical housing and having a heating element in surface contact with and for heating exposed portions of said photosensitive member, the longitudinal axis being positioned transverse to said transfer path and (2) an unheated portion arranged along the longitudinal axis of said cylindrical housing and separated from said heated portion by a thermally insulative material, and
• thermal shielding selectively movable in synchronization with said photosensitive member, between at least one heat shielding position and one non-heat shielding position for protecting and preserving unexposed portions of said photosensitive member, said thermal shield comprising a curved heat shield positioned adjacent to said heating element and being movable concentric about said longitudinal axis between the heat shielding position between said heating element and said photosensitive member and the non-heat shielding position;
• a pressure transfer device for superposing under pressure said photosensitive member and a transfer member;
• and
• a carrying device for carrying said photosensitive member, so that (1) said heat developing device is selectively switchable from a heated state to a non-heated state and the non-heated state to the heated state, (2) said pressure transfer device is selectively switchable from a pressurized state to a non-pressurized state and a non-pressured state to a pressured state, and (3) the direction in which said photosensitive member is carried by said carrying device is changeable.

A method of forming an image with an image formation apparatus, comprising the steps of:

• moving a photosensitive member along a predefined transfer path;
• exposing predefined portions of said photosensitive member to an image;
• providing a heat developer having a cylindrical housing having (1) a heated portion arranged along a longitudinal axis of said cylindrical housing and having a heating element in surface contact with and for heating exposed portions of said photosensitive member, the longitudinal axis being positioned transverse to said transfer path and (2) an unheated portion arranged along the longitudinal axis of said cylindrical housing and separated from said heated portion by a thermally insulative material, and
• heat developing said exposed portions of said photosensitive member so as to form an image through application of heat by said heat developer to said portions;
• carrying said photosensitive member in a positive feed direction while being heated during image development;
• shielding unused portions of said photosensitive member from exposure to heat so as to preserve a usable photosensitive state;
• and
• carrying said photosensitive member in a reverse direction at completion of image formation.