Digital display circuit displayable in analog fashion

A digital display circuit for indicating an analog signal voltage comprising:

• means for generating a plurality of reference voltages quantized at a predetermined voltage width;
• first modulating means for periodically modulating said analog signal so that the modulated signal may alternately have two amplitudes of a higher level and a lower level, the voltage difference between the higher and lower levels being substantially equal to the difference between the highest and lowest reference voltages;
• second modulating means for periodically modulating every each of the reference voltages in synchronization with said first modulating means so that each of the modulated reference voltages may have a section where the amplitude varies as time advanced;
• a plurality of comparators corresponding to each of said plurality of reference voltages for comparing said modulated analog signal voltage with each of said modulated reference voltages and for producing outputs in accordance with the respective compared results;
• selecting means connected to said comparators and having output terminals equal in number to said comparators for generating a drive signal at only one of said output terminals, which is fixed in the relation between the modulated analog signal voltage and the modulated reference voltages;
• a pair of display means each consisting of display elements which are connected to respective output terminals of said selecting means and successively arranged in such a sequence that the order in arrangement of the display element sequence in respective one of said display means pair corresponds to that in amplitude of the reference voltages, and also the element corresponding to the highest reference voltage in one of said display means pair being positioned adjacent to the element corresponding to the lowest reference voltage in the other of said display means pair;
• and
• driving means for alternately rendering said pair of display means operative so that said one of the display means pair may be operative while said modulated analog signal is in the lower level and said the other of the display means pair may be operative while said modulated analog signal is in the higher level,
• one of said display elements which is associated with said drive-signal generated output terminal of the selecting means and also with said operative display means being energized.

A parallel comparison type analog-to-digital converter for performing a parallel comparison of an analog input voltage with a plurality of digitalizing voltages by means of a plurality of comparators to convert the analog input voltage into a digitalized output, comprising:

• control means having first and second control states occuring alternatively for permitting said plurality of comparators to perform a comparison of the analog input voltage in a first voltage range when said control means is in the first control state and for permitting said plurality of comparators to perform a comparison of the analog input voltage in a second voltage range when said control means is in the second control state, said control means comprising an oscillator circuit for operating switch means alternately to switch between the first and second control states and periodically to oscillate one set of the input voltages to said plurality of comparators with an amplitude substantially equal to the difference between the highest and lowest values of the digitalizing voltages, the oscillations being in synchronism with the switching between the first and second control states;
• said oscillator circuit further comprising means for oscillating another set of the input voltages to said plurality of comparators with an amplitude smaller than the unit digitalizing voltage so that the oscillated another set of the input voltage in one cycle may have a section where the amplitude varies as time advanced, and with cycles different from the switching cycles of the first and second control states but in synchronism with the switching of the first and second control states;
• first display means for displaying the outputs from said comparators;
• second display means for displaying the outputs fram said comparators;
• and
• means for operating said first display means in the first control state and operating said second display means in the second control state.