Drive mechanism of optical scanner

A drive mechanism of optical scanner, includes an image pick-up device, a delivery device, a first motor and a second motor, the said image pick-up device can move back and forth in the scan path provided by optical scanner so as to perform image scan. The said delivery device consists of a actuating wheel, a passive wheel and a circular conveyor belt; the circular conveyor belt is harnessed on two rotating wheels and is connected to image pick-up device. The above-mentioned two motors provide rotational power of different rotational speed (torque) to propel the delivery device and rotate, so the image pick-up device is led into the scan path and scans back and forth. Then the scope of scan speed is enlarged to fit in with the required scan speed of the scanner under various resolutions.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Refer to FIG. 2 , diagrammatically represents a first embodiment of the drive mechanism according to optical scanner of the present invention, the drive mechanism comprises an image pick-up device 31 , delivery device 32 , a first motor 33 , a second motor 34 and a controller 35 . The image pick-up device 31 may be an optical path device with a Charged Couple Device (CCD) or a Contact Image Sensor (CIS), it has a guide hole 311 and a roller 312 , the scan path 21 provided by optical scanner 1 consists of two guide bars 211 that parallel each other and guide rail 212 , the image pick-up device matches with guide bars 211 and guide rail respectively by means of guide hole 311 and roller 312 so that it can move back and forth in the scan path 21 to scan the document. The delivery device 32 consists of actuating wheel 321 , passive wheel 322 and a annular conveyor belt 323 ; the above-mentioned two rotating wheels 321 , 322 may be two fixed pulleys or two gears, and annular conveyor belt 323 may be a annular rope sheave (pulley) or annular gear are set in the two ends of scan path 21 , and the annular conveyor belt is harnessed on two rotating wheels 321 , 322 , wherein the annular conveyor belt is parallel with scan path 21 and connects to image pick-up device 31 , furthermore a reduction gear set is set in the axis of actuating gear and a appropriate reduction ratio is provided. The first motor 33 may be a DC motor or stepping motor, on its output shaft the motor 33 is combined with a gear 331 that engages with a set of reduction gear 36 . The first motor 33 provides rotational power of the first rotational speed and the power can drive reduction gear set 36 to promote rotation of delivery device 32 so that the image pick-up device 31 moves back and forth in the scan path 21 in order to scan the document. The second motor 34 may be a DC motor or stepping motor, on its output shaft the motor 34 is combined with a gear 341 that engages with a set of reduction gear 36 . The second motor 34 provides rotational power of the second rotational speed and the power can drive reduction gear set 36 to promote rotation of delivery device 32 so that the image pick-up device 31 moves back and forth in the scan path 21 in order to scan the document. The controller 35 is connected to the first motor 33 and the second motor 34 respectively in the electrical connection way, the drive mechanism 3 is drove only by one of the two motors at the same time and the other motor is controlled in the idle running through control of the controller 35 . Hence according to the invention, the scope of rotational speed (torque) provided by the first motor 33 or second motor 34 is served as the rotational speed (torque) scope of drive mechanism 3 and the rotational speed (torque) scope of drive mechanism 3 is further widened. Due to drive mechanism 3 outputs larger rotational speed (torque) scope according to the invention, thus how the resolution of optical scanner is designed in any case, a appropriate rotational speed (torque) could be found in the drive mechanism 3 to match with optical scanner 1 , so the application scope of drive mechanism 3 of optical scanner 1 is widened relatively. Refer to FIG. 3, a second embodiment of the drive mechanism according to optical scanner of the present invention. Most components within the embodiment are the same as the first embodiment and thus given unnecessary details no more, here only the differences are described. The greatest difference according to the embodiment is that rotational speed (torque) output of the first motor 33 equals to rotational speed (torque) output of the second motor 34 , but different reduction ratio could be created by means of different size of gear combination so that enable two identical motors 33 , 34 to create different scope of rotational speed (torque). For example, the different diameter gears 331 , 341 are mounted on the output shaft of first and second motor 33 , 34 , or a reduction gear set 361 is set between reduction gear ser 36 and the first motor, thus enable the two motors of identical rotational speed (torque) to create larger scope output of rotational speed (torque). Refer to FIG. 4, a third embodiment of the drive mechanism according to optical scanner of the present invention. Besides a reduction gear set 36 is installed on the axis of the actuating wheel 221 according to the embodiment, a reduction gear set 37 is installed on the axis of the actuating wheel 222 simultaneously and enable the output shaft's gear 331 of first motor 33 to engage with the reduction gear set 36 of actuating wheel 321 while the output shaft's gear 341 of second motor 34 to engage with the reduction gear set 37 of actuating wheel 322 . Controller 35 controls both the above-mentioned motors 33 , 34 , now reduction ratios of reduction gear sets 36 , 37 which are installed on the actuating wheel 321 and passive wheel 322 respectively may be identical and motor of different rotational speed (torque) is used, or different reduction ratio of reduction gear sets 36 , 37 and motor of identical rotational speed (torque) is used. It is worthy to mention that although the motor which is used by the above three embodiments may be a DC motor or stepping motor, but a encoder must be added if a DC motor is used so as to track the position of image pick-up device at any time in the scan path. Of course, the drive mechanism of optical scanner according to the present invention has been described above by taking the case as better embodiment, but implementation scope of the present invention is not really limited to the scope of the embodiment described. All of the modifications, which are made by those whose familiar with the art without departing from the spirit of the invention, are belong to the scope of the present invention. Thus the protective scope of the invention is based on the following claims.