| 摘要 |
<p>A laser recorder for recording images on a substrate in response to a video signal (36) having a frequency which defines a pixel time (during which a single pixel is imaged) includes a duty cycle modulating digital to analog (D/A) converter (32) which outputs a variable duty cycle high frequency signal, based upon an intensity controlling N-bit input (34), to a power controller (26) which then controls the intensity of a light beam output by a laser based upon the variable duty cycle high frequency signal. The duty cycle modulating D/A converter outputs a high frequency variable duty cycle bitstream including a repeating cycle of fixed amplitude pulses, a total duration of all of the pulses in each cycle varying based upon the N-bit input signal. The high frequency of the variable duty cycle is sufficiently high so that the cycle of fixed amplitude pulses repeats multiple times within each pixel time, so that the intensity level with which pixels are formed on a substrate varies based upon the number of pulses output during each pixel time and the total duration of all pulses in each cycle. Preferably, the laser, power controller, and duty cycle modulating D/A converter are formed in a common semiconductive substrate. A detector (24) for detecting the intensity of light output by the laser is also preferably formed in the common semiconductive substrate, and provides feedback to the power controller. In a preferred embodiment, the duty cycle modulating D/A converter varies the total duration of the fixed amplitude pulse within a cycle by varying a number of fixed amplitude, fixed width pulses output during each cycle based upon the N-bit input signal. <IMAGE></p> |
