Abstract: In a scanner, a pulse generator generates a pulse signal, a transmissive optical sensor includes a light projector that projects pulsed light corresponding to the pulse signal and a light receiver disposed so as to face the light projector, a peak hold circuit holds a peak value of a voltage value indicating a light reception amount of the pulsed light in the light receiver, and a first current supply circuit increases a light projection amount of the pulsed light projected from the light projector by increasing a current supplied to the light projector when the peak value is smaller than a reference value and decreases the light projection amount of the pulsed light projected from the light projector by decreasing the current supplied to the light projector when the peak value is larger than the reference value.

Abstract: In a scanner, a pulse generator generates a pulse signal, a transmissive optical sensor includes a light projector that projects pulsed light corresponding to the pulse signal and a light receiver disposed so as to face the light projector, a peak hold circuit holds a peak value of a voltage value indicating a light reception amount of the pulsed light in the light receiver, and a first current supply circuit increases a light projection amount of the pulsed light projected from the light projector by increasing a current supplied to the light projector when the peak value is smaller than a reference value and decreases the light projection amount of the pulsed light projected from the light projector by decreasing the current supplied to the light projector when the peak value is larger than the reference value.

Abstract: A scanner includes: a pulse generator that generates a pulse signal; a transmissive optical sensor including a photo transmitter that projects pulsed light in response to the pulse signal and a photo receiver facing the photo transmitter; a charge-discharge unit capable of storing an electric charge of the pulse signal and discharging the stored electric charge; and a controller that causes the charge-discharge unit to discharge the electric charge when the photo receiver receives the pulsed light, causes the charge-discharge unit to store the electric charge when the photo receiver does not receive the pulsed light, and that starts supply of power to a CPU when an amount of the electric charge is at or above a threshold.

Abstract: A scanner includes: a pulse generator that generates a pulse signal; a transmissive optical sensor including a photo transmitter that projects pulsed light in response to the pulse signal and a photo receiver facing the photo transmitter; a charge-discharge unit capable of storing an electric charge of the pulse signal and discharging the stored electric charge; and a controller that causes the charge-discharge unit to discharge the electric charge when the photo receiver receives the pulsed light, causes the charge-discharge unit to store the electric charge when the photo receiver does not receive the pulsed light, and that starts supply of power to a CPU when an amount of the electric charge is at or above a threshold.