Analog-digital converter
AssigneeTokyo Shibaura Electric Co., Ltd.
InventorYukiharu Takahashi
Life of this patent
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Abstract
An analog-digital converter designed to provide digital data by converting analog input voltage signals into pulse signals by a voltage-frequency converter, and counting said pulse signals by a counter, the improvement being that the A-D converter comprises a sequence controller which selectively supplies low-level or high-level input voltage signals to the A-D converter before analog input signals being measured are received therein.
Claims4
An A-D conversion method using a V-F converter for converting an analog voltage signal into an output pulse signal having a frequency corresponding to the voltage level of the analog voltage signal, and a counter for counting the pulses of the output pulse signal from the V-F converter, said method comprising the steps of:
- supplying a reference analog voltage signal of a reference voltage level V.sub.R to the V-F converter for a first predetermined time period T.sub.1 to generate a first output pulse signal having first output pulses of frequency F.sub.R to be counted by the counter, the counter storing a value N=F.sub.R .times.T.sub.1 at the end of said first predetermined time period;
- resetting the counter;
- supplying an analog voltage signal of an unknown voltage level V.sub.U to the V-F converter for a second predetermined time period T.sub.2 to generate a second output pulse signal having second output pulses of frequency F.sub.U to be counted by the counter, the counter storing a value M=F.sub.U .times.T.sub.2 at the end of said second predetermined time period;
- wherein said second predetermined time period T.sub.2 is so chosen as to satisfy the equation ##EQU12## so that the contents M of the counter, after said analog voltage signal of unknown voltage level has been supplied to the V-F converter for said second predetermined time period T.sub.2 denotes a digital representation of the unknown voltage level V.sub.U of said analog voltage signal of an unknown voltage level:
- ##EQU13## where "n" denotes the number of converted pulses.
An A-D conversion method using a V-F converter for converting an analog voltage signal to an output pulse signal having a frequency corresponding to the voltage level of the analog voltage signal, and an up-down counter for counting the pulses of the output pulse signal from the V-F converter, said method comprising the steps of:
- supplying a first reference analog voltage signal of a first voltage level V.sub.R1 to the V-F converter for a first predetermined time period T.sub.1 to generate a first output pulse signal having first output pulses of frequency F.sub.R1 to be counted in a first counting mode by the up-down counter;
- supplying a second reference analog voltage signal of a second voltage level V.sub.R2 to the V-F converter for said first predetermine time period T.sub.1 to generate a second output pulse signal having second output pulses of frequency F.sub.R2 to be counted in a second counting mode by the up-down counter, the up-down counter storing a value N=(F.sub.R1 -F.sub.R2) xT.sub.1 at the end of said second first predetermined time period;
- resetting the up-down counter;
- supplying said first reference analog voltage signal of the first voltage level V.sub.R1 to the V-F converter for a second predetermined time period T.sub.2 to generate the first output pulse signal having first output pulses of frequency F.sub.R1 to be counted in the first counting mode by the up-down counter;
- and
- supplying an analog voltage signal of an unknown voltage level V.sub.U to the V-F converter for said second predetermined time period T.sub.2 to generate a third output pulse signal having third output pulses of frequency F.sub.R3 to be counted in the second counting mode by the up-down counter, the up-down counter storing a value M=(F.sub.R1 -F.sub.RU).times.T.sub.2 at the end of said second predetermined time period;
- wherein said second predetermined time period T.sub.2 is so chosen as to satisfy the equation ##EQU14## so that the contents M of the up-down counter, after said analog voltage signal of said unknown voltage level has been supplied to the V-F converter for said second predetermined time period T.sub.2 comprises a digital representation of the voltage level V.sub.U of said unknown voltage level;
- where "n" denotes the number of converted pulses.
Dependencies are inferred from the claim text.