Patent ID: 8910937

Claim:
A sheet medium detection device, comprising: a light guide bar provided on one side of a medium conveying passage and provided with a plurality of reflection surfaces arranged with intervals along a length direction of the light guide bar, wherein each of the reflection surfaces reflects the light within the light guide bar to the other side of the medium conveying passage; a plurality of light receivers, each of which, being opposite to a reflection surface of the light guide bar, is provided on the other side of the medium conveying passage; and a point light source; wherein two ends of the light guide bar are provided with the point light source respectively; the reflection surface is formed by a cutting groove inside the light guide bar; the start point of the cutting groove is located at the side of the light guide bar far from the medium conveying passage, the end point of the cutting groove is located inside the light guide bar; a distance between the end point and the point light source corresponding to the end point is greater than a distance between the start point and the point light source corresponding to the start point, so that an angle from a side of the point light source directly facing the reflection surface to the plane of the medium conveying passage is an obtuse angle.