| 摘要 |
A media sensor 68 includes a cap 85 with a common opening 85 b for restricting the beam spread of light emitted from a light-emitting element 82 and the range of light receivable by a light-receiving element 83 , while suppressing the effects of disturbance. Accordingly, the media sensor 68 can prevent a decline in detection accuracy while using inexpensive elements with low directivity. Since the light-emitting element 82 and light-receiving element 83 are oriented perpendicularly to the paper P, the media sensor 68 is superior to sensors equipped with elements disposed at an angle to the paper P by avoiding a decline in detection accuracy caused by errors in the angular positioning of the elements, errors in angular positioning of the sensor itself, and the like, and by reducing the space required in the sensor to dispose the elements, thereby reducing the size of the sensor.
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