Contact image sensor and image forming apparatus

An image forming apparatus comprising:

• an image reading device including a housing, a light source provided on an upper part of the housing to irradiate light to a document, lenses arranged in the housing at least on an entering side and an outgoing side to focus reflected light from a reading position of the document, an aperture angle regulation member having an inclined surface to reflect a part of light irradiated from the light source at the document reading position and an aperture portion to permit the reflected light to enter directly to regulate an aperture angle to permit the reflected light passing through the aperture portion to be irradiated to the lens on the entering side, and a light receiving element array to receive and photoelectrically convert the reflected light focused after passing through the lenses;
• a sheet supply portion to store sheets;
• an image forming portion to form an image read by the image reading device on a sheet supplied from the sheet supply portion;
• and
• a sheet discharge portion to discharge the sheet with the image formed.

An image reading method of a contact image sensor comprising:

• irradiating light from a light source toward a document reading position;
• focusing reflected light from the document reading position via lenses installed at least on an entering side and an outgoing side;
• leading the light from the light source directly to the document reading portion, and reflecting a part of the light from the light source on a inclined surface, which is formed on aperture angle regulation member having an aperture portion to permit the reflected light from the document to enter directly to regulate an aperture angel to permit the reflected light to be irradiated to the lens on the entering side, to lead the light to the document reading portion;
• and
• receiving and photoelectrically converting the reflected light focused when the light led to the document reading position is reflected and passes through the lenses by a light receiving element array.