Pixel clock and pulse-modulation-signal generating device, optical scanner, and image forming apparatus

A pixel clock and pulse-modulation-signal generating device, comprising:

• a high-frequency-clock generating unit that generates a high-frequency clock;
• a modulation-data generating unit configured to receive and use pixel control data that assigns a pixel length and image data to generate phase data that indicates a transition timing of a pixel clock and modulation data that indicates a desired bit pattern that corresponds to the image data;
• a pixel-clock generating unit configured to receive and use the high-frequency clock, the phase data and a horizontal synchronization signal to generate the pixel clock with the transition timing indicated by the phase data;
• and
• a serial-modulation-signal generating unit configured to receive and use the modulation data, the high-frequency clock, and the pixel clock to output a pulse modulation signal in a serial pulse string based on the high-frequency clock, wherein
• the modulation-data generating unit adds data to or deletes data from the modulation data based on the pixel control data, and
• data at an arbitrary position in the modulation data is deleted when a length of a pixel is to be shortened.