Optical device, image reading unit, and image forming apparatus correcting a width of a slit for reflected light

An optical device comprising:

• an upper housing that restricts part of reflected light from a target object,
• wherein the upper housing comprises resin, and
• wherein the upper housing has a slit and a hole, the slit extending in a first direction crossing a propagation direction of the reflected light and formed at an upstream end in the propagation direction, the hole extending through the upper housing in the propagation direction;
• at least one lens array configured to transmit the reflected light that has passed through the slit;
• and
• a lower housing that holds the at least one lens array, and that is configured to contact with part of an inner circumferential surface of the hole to correct a width of the slit,
• wherein the lower housing includes a body that holds the at least one lens array in between in a width direction crossing the first direction and the propagation direction, and the body has an outer peripheral surface that faces outward in the width direction, and from which a plurality of projections protrude outward in the width direction,
• wherein the upper housing includes a plurality of covers that cover the projections from an outer side of the width direction and in the first direction, and
• wherein an adhesive is filled in between the projections and the covers.

An optical device comprising:

• an upper housing that restricts part of reflected light from a target object,
• wherein the upper housing comprises resin, and
• wherein the upper housing has a slit and a hole, the slit extending in a first direction crossing a propagation direction of the reflected light and formed at an upstream end in the propagation direction, the hole extending through the upper housing in the propagation direction;
• at least one lens array configured to transmit the reflected light that has passed through the slit;
• and
• a lower housing that holds the at least one lens array, and that is configured to contact with part of an inner circumferential surface of the hole to correct a width of the slit,
• wherein the lower housing includes a body that holds the at least one lens array in between in a width direction crossing the first direction and the propagation direction, and the body has an outer peripheral surface that faces outward in the width direction, and from which a projection protrudes at a center portion in the first direction, and
• wherein the upper housing includes a pair of holders that hold the projection in the first direction.

An optical device comprising:

• an upper housing that restricts part of reflected light from a target object,
• wherein the upper housing comprises resin, and
• wherein the upper housing has a slit and a hole, the slit extending in a first direction crossing a propagation direction of the reflected light and formed at an upstream end in the propagation direction, the hole extending through the upper housing in the propagation direction;
• at least one lens array configured to transmit the reflected light that has passed through the slit;
• and
• a lower housing that holds the at least one lens array, and that is configured to contact with part of an inner circumferential surface of the hole to correct a width of the slit,
• wherein the at least one lens array includes a pair of lens arrays overlapping each other in the propagation direction,
• wherein a second adhesive is applied to the pair of lens arrays from an outer side in a width direction crossing the first direction and the propagation direction at a plurality of portions across the pair of lens arrays, and
• wherein the lower housing includes a body that holds the at least one lens array in between in the width direction and that extends in the first direction, and the body has opposing surfaces that oppose the pair of lens arrays and on which a plurality of recesses are formed to define gaps between the opposing surfaces and the second adhesive.