A closed circuit control device for controlling carrier speed of a scanner. An optical meter is attached to the transparent glass panel of a scanner such that an image of the optical meter is formed on an optical sensor such as a charge couple device or a contact image sensor. Image of the optical meter is converted into sense signals by the optical sensor so that speed of the carrier can be accurately computed. Through the acquisition of an accurate carrier speed, scanning speed and direction can be precisely controlled.

A document transport for a scanner (100) has a flexible, elongated finger (226) disposed adjacent to a document (134), and a force applied to the finger (226) urges teeth (233) on the finger (226) into contact with the document (134) which urges the document (134) along a path through the scanner (100). A piezoelectric plate (222), which applies the force to the finger (226), requires only a small amount of electrical power. To traverse the scanner (100), a document (134) may also be manually fed along a guide (272). First and second speed-sensing detectors (276a and 276b), disposed along the path traversed by the document (134), permit the scanner (100) to determine a speed at which the manually fed document (134) traverses the scanner (100). To conserve electrical energy, the scanner (100) also includes a document-presence detector (274) for activating the scanner (100) when a document (134) to be scanned is present.

An image reader, detachably attached to an electronic apparatus, for functionally expanding the electronic apparatus and for reading an image on a medium, includes an interface connectible to and disconnectible from the electronic apparatus a housing having an image-reading surface that faces the medium, a medium detecting part, provided on the image-reading surface, for detecting the medium, and an image reading part, provided on the image-reading surface and driven based on a detection result by the medium detecting part, for reading the image on the medium.

An optical ruler is provided on the back surface side of the top housing and close to the transparent window along a scanning direction for providing a calibration reference. The optical ruler is formed with black and white blocks alternately arranged in an array. An image sensor which has a width larger than the width of the transparent window is provided for reading the image information of the optical ruler along with a scanned sheet while being progressively driven by a step motor. A determining element computes the actual moving steps of the step motor by calculating the number of black and white pixels from the scanned image of the optical ruler. When the actual moving steps of the step motor are fewer than a predetermined threshold value, or when the frequency of the occurrences of the scan line losses is higher than a predetermined threshold value, the image sensor is driven by the step motor to scan the sheet again. As a result, the step motor can be operated in response to a closed loop control signal depending on the actual moving steps of the step motor.

An optical scanner including a scanner head, a roller engaged by a record, the roller including optically readable marks, light sources and sensor which illuminate and sense both roller and the record, a lens for focusing light from the record onto the sensor, and a lens mirror for focusing light from the roller onto the sensor.