Optical scanner having a variable resolution

Abstract

An optical scanner having a variable resolution wherein an optical detecting unit controlled by a pixel clock signal generates a discrete signal representing pixels scanned in a region. An analog-to-digital converter converts the signal to a digital signal with a preselected resolution controlled by a sample clock generator. The sample clock generator receives the pixel clock signal, and through a counter and a store, operates an addressed, binary data word which is sent to a register. The register is coupled to a further periodic clock generator that controls reading from the register and provides a clock signal with pulses when the bits of the data word assume a first binary state, and no pulses when the bits assume a second binary state. The clock signal is passed to the analog-to-digital converter as a sample clock signal.

I claim:  
     
       1. An optical scanner having a  variable resolution comprising; 
       an optical detecting unit which, controlled by a controller generated pixel clock signal, applies a discrete signal representing pixels in a scanned region;  
       a filter for filtration of the discrete signal; 
       a sample clock generator comprising a counter, a store, and a first register;  
       a clock-controlled analog-to-digital converter connected to receive the discrete signal from the filter, said converter converts  and convert the discrete signal to a digital signalhaving a preselected resolution, said resolution being controlled by the sample clock generator ;  
       said counter receiving the pixel clock signal and generating a multibit signal;  
       said store containing binary data words, said multibit signal from the counter serving as an address signal for the store, an addressed, binary data word generated and read by the store  to read out a binary data word from said store;  
       said first register receiving the read, binary data word from the store and being coupled to a second periodic  clock generator which controls reading from the register so as to provide a sample clock signal having clock pulses when individual bits of the data word assume a first binary state, and having no clock pulses when the individual bits of data word assume a second binary state, said clock signal being passed to the analog-to-digital converter as a sample clock signal  whereby the signal provided by the optical detecting unit is sampled.  
     
     
       2. An optical scanner according to claim  1 , wherein the optical detecting unit comprises a CCD array connected to a sample and hold circuit, and said sample and hold circuit holding signals at levels for a period corresponding to a pixel clock period. 
     
     
       3. An optical scanner according to claim  1 , wherein the optical detecting unit further comprises at least two CCD arrays having signals; at least two sample and hold circuits, each connected to one of the CCD arrays, each sample and hold circuit holding signal levels for a period corresponding to a pixel clock period; and said optical scanner further comprising a multiplexer for multiplexing the signals from the sample and hold circuits, said multiplexer generating an output signal corresponding to a line located transversely to the scanned region. 
     
     
       4. An optical scanner according to claim  3 , wherein the store comprises a RAM containing information on how the signals from the individual CCD arrays are to be multiplexed and including: 
       multiplexed data words generated by the multiplexer; the multiplexed data words having addresses selected by the counter; and  
       said optical scanner further comprising a fourth register to receive the multiplexed data words from the RAM; a decoder connected to the counter to control reading and transferring the multiplexed data words to the forth register; and a correct scanning line determined by the multiplexed data words in the fourth register, said multiplexed data words joining signals from the individual CCD arrays.  
     
     
       5. An optical scanner according to claim  1 , wherein the filter comprises an analog lowpass filter which smooths the discrete signal. 
     
     
       6. An optical scanner according to claim  1 , wherein the analog-to-digital converter converts the discrete signal to a digital signal; the filter comprises a digital filter which uses weighed averaging, and the digital filter averages digital grey level values for a pixel with digital grey level values for adjacent pixels. 
     
     
       7. An optical scanner according to claim  1 , further comprising: 
       a variable gain amplifier connected to the filter  coupled to receive a signal sequence from said optical detecting unit;  
       said detecting unit having light sensitive cells; and  
       the variable gain amplifier regulating an amplitude of a signal sequence from the filter  said optional detecting unit in response to the light sensitive cells.  
     
     
       8. An optical scanner according to claim  7 , wherein the store comprises a RAM having stored therein data words with information on variations of the light-sensitive cells of the detecting unit located transversely to the scanning line, the data words having addresses selected by the counter; and 
       said optical scanner further comprising a third register to receive the data words from the RAM; a decoder connected to the counter to control reading and transferring the data words to the third register; and said variable gain amplifier generating signal sequences of the discrete signal which are regulated by the data words.  
     
     
       9. An optical scanner according to claim  1 , wherein the analog-to digital converter comprises a threshold value comparator which compares a threshold value to a signal received from the filter  optical detecting unit at a sampling time and generates a 1-bit value binary signal. 
     
     
       10. An optical scanner according to claim  9 , wherein the threshold value comparator comprises a digital comparator which compares a digital signal with a digital threshold value. 
     
     
       11. An optical scanner according to claim  9 , wherein the store comprises a RAM having stored therein data words having information on local threshold values located transversely to the scanning line; said data words having addresses selected by the counter; and 
       said optical scanner further comprising a second register to receive the data words from the RAM; a decoder connected to the counter to control reading and transferring the data words, and the threshold value comparator using data words from the second register to generate an actual, local threshold value.  
     
     
       12. An optical scanner according to claim  11 , further comprising a digital-to-analog converter to transfer the data words of the second register to the comparator, and said digital-to-analog converter generating an analog threshold value representation of the data words. 
     
     
       13. An optical scanner according to claim  11 , wherein, the data words of the second register are transferred to the comparator as a multibit threshold value representation. 
     
     
       14. An optical scanner according to claim  1 , wherein the analog-to-digital converter samples the discrete signal and generates a multibit, digital signal controlled by the sample clock generator. 
     
     
       15. An optical scanner according to claim  1 , wherein the counter comprises an incremental counter which counts clock pulses, and the incremental counter generates a multibit signal having information on a position of an actual pixel in a scanning line. 
     
     
       16. An optical scanner according to claim  1 , wherein the store comprises a RAM having stored therein data words selected by the counter; and 
       said optical scanner further comprising a decoder connected to the counter to control reading and transferring the data words to the first register.  
     
     
       17. An optical scanner according to claim  1 , wherein the second clock generator comprises a multiplication means which multiplies the pixel clock signal by N, where N is an integer greater than or equal to 1. 
     
     
       18. An optical scanner according to claim  17 , wherein the multiplication means multiplies the pixel clock signal by two. 
     
     
       19. An optical scanner having a variable resolution comprising: 
       an optical detecting unit which, controlled by a controller generated pixel clock signal, applies a discrete signal representing pixels scanned in a region;  
       an analog filter for lowpass filtration of the discrete signal;  
       a clock-controlled analog-to-digital converter which converts the discrete signal to a digital signal having a preselected resolution, said resolution being controlled by a sample clock generator;  
       said sample clock generator comprising a counter, a store, as well as a first register;  
       said counter receiving the pixel clock signal and generating a multibit signal;  
       said store containing binary data words, said multibit signal from the counter serving as an address signal, an addressed, binary data word generated and read by the store; and  
       said first register receiving the read binary data word from the store and being coupled to a second periodic clock generator which controls reading from the register so as to provide a clock signal having clock pulses when individual bits of the data word assume a first binary state, and having no clock pulses when the individual bits of the data word assume a second binary state, said clock signal being passed to the analog-to-digital converter as a sample clock signal.  
     
     
       20. An optical scanner according to claim  19 , wherein the optical detecting unit comprises a CCD array connected to a sample and hold circuit, and said sample and hold circuit holding signal levels for a period corresponding to a pixel clock period. 
     
     
       21. An optical scanner according to claim  19 , wherein the analog lowpass filter smooths the discrete signal. 
     
     
       22. An optical scanner according to claim  19  further comprising: 
       a variable gain amplifier coupled to the filter;  
       said detecting unit having light sensitive cells; and  
       the variable gain amplifier regulating an amplitude of a signal sequence from the filter in response to the light sensitive cells.  
     
     
       23. An optical scanner according to claim  22 , wherein the store comprises a RAM having stored therein data words with information on variations of the light-sensitive cells of the scanning unit located transversely to the scanning line, the data words having addresses selected by the counter; and 
       said optical scanner further comprising a third register to receive the data words from the RAM; a decoder connected to the counter to control reading and transferring the data words to the third register; and said variable gain amplifier generating signal sequences of the discrete signal which are regulated by the data words.  
     
     
       24. An optical scanner according to claim  19  wherein the analog-to-digital converter comprises a threshold value comparator which compares a threshold value to a signal received from the filter at sampling time and generates a 1-bit value binary signal. 
     
     
       25. An optical scanner according to claim  24   61 , wherein the store comprises a RAM having stored therein data words having information on local threshold values located transversely to the scanning line;, said data words having addresses selected by the counter; and 
       said optical scanner further comprising a second register to receive the data words from the RAM; a decoder connected to the counter to control reading and transferring the data words; and the threshold value comparator using data words from the second register to generate an actual, local threshold value.  
     
     
       26. An optical scanner according to claim  25   42 , further comprising a digital-to-analog converter to transfer the data words of the second register to the comparator, and said digital-to-analog converter generating an analog threshold value representation of the data words. 
     
     
       27. An optical scanner according to claim  19  wherein the analog-to-digital converter samples the discrete signal and generates a multibit, digital signal controlled by the sample clock generator. 
     
     
       28. An optical scanner according to claim  19 , wherein the counter comprises an incremental counter which counts clock pulses, and the incremental counter generates a multibit signal having information on a position of an actual pixel in a scanning line. 
     
     
       29. An optical scanner according to claim  19 , wherein the store comprises a RAM having stored therein data words selected by the counter; and 
       said optical scanner further comprising a decoder connected to the counter to control reading and transferring the data words to the first register.  
     
     
       30. An optical scanner according to claim  19 , wherein the further clock generator comprises a multiplication means which multiplies the pixel clock signal by N, where N is an integer greater than or equal to 1. 
     
     
       31. An optical scanner according to claim  30 , wherein the multiplication means multiplies the pixel clock signal by two. 
     
     
       32. An optical scanner having a variable resolution comprising: 
       an optical detecting unit which, controlled by a controller generated pixel clock signal, applies a discrete signal representing pixels scanned in a region;  
       an analog-to-digital converter for converting the discrete signal to a digital multibit signal;  
       an digital filter for filtration of the multibit signal;  
       a sample clock generator comprising a counter, a store, and a first register;  
       a digital comparator for comparing the filtered signal with a digital threshold value representation received from the first register and said digital comparator generating a digital signal; 
       a clock- controlled analog - to - digital converter connected to receive the discrete signal and convert the discrete signal to a digital signal;    
         a memory into which output data from the analog - to - digital converter are written;   
       said counter receiving the pixel clock signal and generating a multibit signal;  
       said store containing binary data words, said multibit signal from the counter serving as an address signal, an addressed binary data word being read from by store  for reading out a binary data word from said store;  
       said first register receiving the read binary data word from the store and being coupled to a second periodic  clock generator which controls reading from the register so as to provide a sample clock signal having clock pulses when the individual bits of the data word assume a first binary state, and having no clock pulses when the bits of the data word assume a second binary state, said clock signal being passed to the analog-to-digital converter as a sample clock signal  to control writing to the memory.  
     
     
       33. An optical scanner according to claim  32 , wherein the optical detecting unit comprises a CCD array connected to a sample and hold circuit, and said sample and hold circuit holding signals at levels for a period corresponding to a pixel clock period. 
     
     
       34. An optical scanner according to claim  32 , wherein the optical detecting unit further comprises at least two CCD arrays having signals; at least two sample and hold circuits, each connected to one of the CCD arrays, each sample and hold circuit holding respective signal levels for a period corresponding to a pixel clock period; and 
       said optical scanner further comprising a multiplexer for multiplexing the signals from the sample and hold circuits, said multiplexer generating an output signal corresponding to a line located transversely to the scanned region.  
     
     
       35. An optical scanner according to claim  34 , wherein the store comprises a RAM containing information on how the signals from the individual CCD arrays are to be multiplexed and including: 
       multiplexed data words generated by the multiplexer, the multiplexed data words having addressed selected by the counter; and  
       said optical scanner further comprising a fourth register to receive the multiplexed data words from the RAM; a decoder connected to the counter to control reading and transferring the multiplexed data words to the fourth register; and a correct scanning line determined by the multiplexed data words in the fourth register; and said multiplexed data words used for joining signals from the individual CCD arrays.  
     
     
       36. An optical scanner according to claim  32 , wherein the analog-to-digital converter converts the discrete signal to a digital signal; the filter comprises a digital filter which uses weighed averaging, and the digital filter averages digital grey level values for a pixel with digital grey level values for adjacent pixels. 
     
     
       37. An optical scanner according to claim  36 , wherein the filter comprises a high order digital filter which interpolates digital grey level values for the pixel on the basis of grey level values for at least one adjacent pixel by use of a higher order interpolation factor. 
     
     
       38. An optical scanner according to claim  32  further comprising: 
       a variable gain amplifier coupled to the filter  receive a signal sequence from said optical detecting unit;  
       said optical detecting unit having light sensitive cells; and  
       the variable gain amplifier regulating an amplitude of a  the signal sequence from the filter  optical detecting unit in response to the light sensitive cells.  
     
     
       39. An optical scanner according to claim  38 , wherein the store comprises a RAM having stored therein data words with information on variations of light-sensitive cells of the detecting unit located transversely to the scanning line, the data words having addresses selected by the counter; and 
       said optical scanner further comprising a third register to receive the data words from the RAM; a decoder connected to the counter to control reading and transferring the data words to the third register; and said variable gain amplifier generating signal sequences of the discrete signal which are regulated by the data words.  
     
     
       40. An optical scanner according to claim  32 , wherein the analog-to-digital converter comprises a threshold value comparator which compares a threshold value to a signal received from the filter  optical detecting unit at a sampling time and generates a 1-bit value binary value  signal. 
     
     
       41. An optical scanner according to claim  40 , wherein the threshold value comparator comprises a digital comparator which compares a digital signal with a digital threshold value. 
     
     
       42. An optical scanner according to claim  40 , wherein the store comprises a RAM having stored therein data words having information on local threshold values located transversely to the scanning line; said data words having addresses selected by the counter; and 
       said optical scanner further comprising a second register to receive the data words from the RAM; a decoder connected to the counter to control reading and transferring the data words, and the threshold value comparator using data words from the second register to generate an actual, local threshold value.  
     
     
       43. An optical scanner according to claim  42 , wherein the data words of the second register are transferred to the comparator as a multibit threshold value representation. 
     
     
       44. An optical scanner according to claim  32 , wherein the counter comprises an incremental counter which counts clock pulses, and the incremental counter generates a multibit signal having information on a position of an actual pixel in a scanning line. 
     
     
       45. An optical scanner according to claim  32 , wherein the store comprises a RAM having stored therein data words selected by the counter; and 
       said optical scanner further comprising a decoder connected to the counter to control reading and transferring the data words to the first register.  
     
     
       46. An optical scanner according to claim  32 , wherein the second clock generator comprises a multiplication means, which multiplies the pixel clock signal by N, where N is an integer greater than or equal to 1. 
     
     
       47. An optical scanner according to claim  46 , wherein the multiplication means multiplies the pixel clock signal by two. 
     
     
       48. An optical scanner according to claim  1  where said clock signal for controlling said analog- to - digital converter is said sample clock signal.   
     
     
       49. An optical scanner according to claim  1 , further comprising a filter, the filter to receive the signal from said optical detecting unit. 
     
     
       50. An optical scanner according to claim  1  wherein said clock signal for controlling said analog- to - digital converter is generated by the pixel clock controller.   
     
     
       51. An optical scanner according to claim  1  further comprising a digital threshold comparator, the digital threshold comparator to receive the discrete signal from the optical detecting unit and the digital threshold comparator controlled by the sample clock generator. 
     
     
       52. An optical scanner according to claim  51  wherein the store comprises a RAM having stored therein data words having information on local threshold values located transversely to the scanning line; said data words having addresses selected by the counter; and 
       
         said optical scanner further comprising a second register to receive the data words from the RAM; a decoder connected to the counter to control reading and transferring the data words, said threshold value comparator using data words from the second register to generate an actual, local threshold value. 
       
     
     
       53. An optical scanner according to claim  52  wherein the data words of the second register are transferred to the comparator as a multibit threshold value representation. 
     
     
       54. An optical scanner according to claim  1  further comprising a digital filter, to filter the digital signal from the analog- to - digital converter.   
     
     
       55. An optical scanner according to claim  54  wherein said digital filter is a FIR filter. 
     
     
       56. An optical scanner according to claim  1  further comprising a digital filter to filter the digital signal from the analog- to - digital converter, the digital filter to interpolate new sample values between digital signals from the analog - to - digital converter.   
     
     
       57. An optical scanner according to claim  56  wherein said digital filter is a FIR filter. 
     
     
       58. An optical scanner according to claim  32  wherein said clock signal for controlling said analog- to - digital converter is said pixel clock signal.   
     
     
       59. An optical scanner according to claim  32  further comprising a filter to receive and smooth the discrete signal. 
     
     
       60. An optical scanner according to claim  32  wherein said clock signal for controlling said analog- to - digital converter is generated by the pixel clock controller.   
     
     
       61. An optical scanner according to claim  32  further comprising a digital threshold comparator to receive the digital signal, the digital threshold comparator controlled by the pixel clock controller. 
     
     
       62. An optical scanner according to claim  32  further comprising a digital filter for filtering a digital signal from the analog- to - digital converter.   
     
     
       63. An optical scanner according to claim  62  wherein said digital filter is a FIR filter. 
     
     
       64. An optical scanner according to claim  32  further comprising a digital filter, to filter the digital signal from the analog- to - digital converter, the digital filter to interpolate new sample values between digital signals from the analog - to - digital converter.   
     
     
       65. An optical scanner according to claim  64  wherein said digital filter is a FIR filter.