JPH0394828U

JPH0394828U -

Info

Publication number: JPH0394828U
Application number: JP300390U
Authority: JP
Priority date: 1990-01-17
Filing date: 1990-01-17
Publication date: 1991-09-27

Description

[Brief explanation of drawings]

第１図は本考案の第１の実施例を示す回路図、
第２図は第１図の回路を実際の機器に使用した様
子を示す回路図、第３図は比較器の詳細な構成を
示す回路図、第４図は不感帯の幅を示すグラフ、
第５図は不感帯の幅が閾値電圧ＶＴＨによつて変
化する様子を示すグラフ、第６図は閾値電圧の自
動調整を行うための手順を示すフローチヤート、
第７図は閾値電圧の自動調整時に確認用に用いら
れる入力信号電圧を示すグラフ、第８図は比較回
路の変形例を示す回路図、第９図は従来用いられ
ている反転型のシユミツト・トリガ回路の一例を
示す回路図、第１０図はその入出力特性を示すグ
ラフである。１，２……比較器、３……通過検知センサ、４
，６……Ｄ−Ａコンバータ、５……Ｖ−Ｉコンバ
ータ、１０……比較回路、１１……ＣＰＵ、１２
……ＲＯＭ、１３……ＲＡＭ、２０……制御部。 FIG. 1 is a circuit diagram showing a first embodiment of the present invention;
Figure 2 is a circuit diagram showing how the circuit in Figure 1 is used in an actual device, Figure 3 is a circuit diagram showing the detailed configuration of the comparator, Figure 4 is a graph showing the width of the dead zone,
FIG. 5 is a graph showing how the width of the dead zone changes depending on the threshold voltage VTH, and FIG. 6 is a flowchart showing the procedure for automatically adjusting the threshold voltage.
Fig. 7 is a graph showing the input signal voltage used for confirmation during automatic adjustment of the threshold voltage, Fig. 8 is a circuit diagram showing a modified example of the comparison circuit, and Fig. 9 is a graph showing a conventionally used inverting Schmitt circuit. A circuit diagram showing an example of the trigger circuit, and FIG. 10 is a graph showing its input/output characteristics. 1, 2... Comparator, 3... Passage detection sensor, 4
, 6... D-A converter, 5... V-I converter, 10... Comparison circuit, 11... CPU, 12
...ROM, 13...RAM, 20...control unit.

Claims

[Claims for Utility Model Registration] 1. A first comparator that inputs and compares an input signal to one input terminal and a threshold value to be compared to the other input terminal, and the output of this first comparator. a first power supply connected to via a resistor, the output of the first comparator as input on one side, a voltage obtained by dividing the first power supply voltage as input on the other side, and the input voltage on one side is a second comparator that generates an open circuit output when the voltage is higher than the other side input voltage, and a ground level output when the one side input voltage is lower than the other side input voltage; and an input terminal of the first comparator; a second power supply for supplying a voltage; and generating two different threshold voltages from the voltage of the second power supply according to the output of the second comparator to input the other side of the first comparator. A comparison circuit equipped with a threshold generation circuit to be input to a terminal. 2. The second power source is a variable voltage power source, and the threshold generation circuit is a resistive voltage divider circuit that divides the voltage between the second comparator output and the second power source. comparison circuit. 3. The second power source is a fixed voltage power source, and the threshold generation circuit is a voltage dividing circuit that divides the voltage between the second comparator output and the second power source using a fixed resistor and a variable resistor connected in series. A comparison circuit characterized by: