Electronic photograph printer

An electronic photograph printer comprising:

• a photosensitive drum that is rotative relative to a recording paper;
• a static-charging apparatus for statically charging a surface of the photosensitive drum uniformly;
• an exposure apparatus for forming a static latent image on the surface of the photosensitive drum statically charged by the static-charging apparatus;
• a rotative developer roll making contact with the photosensitive drum;
• a developer apparatus for supplying a toner from the developer roll to the photosensitive drum and forming a toner image by visualizing the static latent image onto the surface of the photosensitive drum;
• a roll-support member rotatably supporting the developer roll via a bearing;
• and
• a pressing mechanism for discharging an elastically biasing force to the roll-support member and pressing the developer roll of the developer apparatus onto the photosensitive drum;
• wherein the pressing mechanism comprises:
• an air cylinder apparatus configured to apply the elastically biasing force to the roll-support member;
• an air-pressure-supply line configured to convey air pressure supplied from an air pressure source to the air cylinder apparatus;
• and
• a decompression valve disposed in the air-pressure-supply line;
• and
• wherein the decompression valve is configured to maintain a fixed degree of air pressure between the decompression valve and the air cylinder apparatus, in an air pressure circuit used for supplying air pressure from the air pressure source to the air cylinder apparatus via the air-pressure-supply line;
• the roll-support member is formed as a circular member in which the bearing is placed at a position different from a center position of the circular member, and is configured so that a distance between the bearing and the photosensitive drum is changed by rotating the circular member;
• and
• the air cylinder apparatus is configured to apply the elastically biasing force to rotate the roll-support member.