Light source unit of image-reading apparatus and image-reading apparatus with light source unit

An image-reading apparatus comprising:

• a light source unit that includes,
• a light source section on which a plurality of light-emitting elements that emit light toward a medium whose image is read by an image-capturing unit are arranged in a main-scanning direction, and
• a diffusion unit that transmits and diffuses therein the light emitted from the light-emitting elements,
• wherein a pattern for suppressing light emission to an outside is formed at a position opposite each of the plurality of light-emitting elements in the diffusion unit;
• a rib provided in a frame of the image-reading apparatus, the rib being capable of being fitted with the cutout portion when the light source unit is assembled;
• and
• a fixing member for fixing the light source unit to the frame with the cutout portion being fitted with the rib and the light source unit being mounted on the frame, wherein
• the light source section of the light source unit including a connector provided at one end of the main-scanning direction and a cutout portion provided at the other end of the main-scanning direction,
• the diffusion unit of the light source unit having a shape through which the light source section is inserted,
• a size of the diffusion unit in the main-scanning direction being equal to or shorter than a distance between the connector and the cutout portion.