| 摘要 |
PURPOSE:To keep the quantity of light from a light source constant at any time by accurately detecting the quantity of the light by exercising control over the quantity of the light while detecting the quantity of the light from the light source, by detecting the quantity of reflected light from a rotary mirror directly in an optical reader which reads core information. CONSTITUTION:Light from light source 1 reaches code information appended to article 7 placed on scanning window 6 by way of reflecting plate 2, rotary mirror 4, and fixed mirrors 5a-5n arranged on a semicircle track centering on rotary mirror 4, and the information is read. Light-quantity detecting method 12, arranged among fixed mirrors 5a-5n, detects the quantity of light arriving via rotary mirror 4 and its detection signal is input to light-quantity control method 14 via sample holding and feedback circuit 13 to control the quantity of the light of light source 1. Consequently, the quantity of the light can accurately be detected without any loss of the arrival light and the quantity of the light of the light source can be kept constant at any time. |
