JPS6241453Y2 - - Google Patents

Description

[Detailed explanation of the idea] The present invention relates to an improvement of a dead zone generating circuit.

In general, a dead zone generating circuit has an output voltage V _O with respect to an input voltage V _IN in a certain region NS as shown in Fig. 1.
becomes zero and the input voltage V _I is outside the above region NS
This is a circuit in which the output voltage V _O outputs in proportion to the input voltage with respect to _N. Conventionally, this type of circuit has a diode configuration as shown in Figure 2, and a calculation type as shown in Figure 3. Some use an amplifier.

The dead zone generation circuit in Figure 2
By applying a reverse bias voltage to D ₁ to _{D 4} , the voltage at which each diode D ₁ to _{D 4} is turned on has a width, thus forming a dead zone. However, this type of dead zone generation circuit has temperature dependence because the forward drop voltage of the diode is dependent on temperature due to the characteristics of the diode as a circuit element, and each diode has temperature dependence. Since the rise characteristic of is not linear, the fourth
As shown in the figure, the disadvantage is that the rise characteristics at the break point when exiting the dead zone are unavoidably blunted. In addition, in FIG. 4, the value of the break point is R ₂ /R ₁ V _B ,R
₄ /R ₃ V _B , and the slope of the linear portion becomes R/R ₂ and R/R ₄ .

The dead zone generating circuit shown in FIG. 3 improves the roundness of the rise characteristic at this corner point. The circuit consists of a first operational amplifier A1 that shares the positive input voltage range and a second operational amplifier _A1 that shares the negative input voltage range.
, and _{an addition operational amplifier A 3 for} adding the first and second operational outputs. The input terminal of amplifier _A1 has a positive bias voltage +V _B
When a positive input voltage V _IN arrives at the input terminal T _IN , a positive voltage is applied to the input terminal of the amplifier _A1 , and a negative voltage is generated at the output terminal. turns on the diode D ₁ connected in parallel between the input and output terminals of the amplifier A ₁ and turns off the diode D ₂ connected in series to the output terminal, thus making the output voltage at the output terminal of the amplifier A ₁ OV, On the other hand, when a negative input voltage arrives at the input terminal T _IN and becomes greater than the bias voltage V _B , the diode D ₁ is turned off and the diode D ₂ is turned on, thus causing V _O to appear at the output terminal of the amplifier A ₁ . It is designed to output _a positive voltage of =R/ _{R1VIN -} R/ _R2VB .

On the other hand, amplifier A ₂ has a bias voltage at the input terminal of -
V _B , and the configuration is the same as that for the amplifier A ₁ , except that the connection direction of the diode D ₃ in parallel and the diode D ₄ in series with the amplifier A ₂ is reversed from that of the amplifier A ₁ , Thus, the input terminal T _IN
When a negative input voltage arrives at the input terminal, the output voltage at the output terminal of the amplifier _A2 becomes OV, whereas a positive input voltage V _IN arrives at the input terminal T _IN , and the bias voltage V
When the voltage becomes larger than _B , V is applied to the output terminal of amplifier _A2 .
It is designed to output _a negative voltage of _O =-(R/ _{R3VIN -} R/ _R4VB ).

The operational outputs of amplifiers _A1 and _A2 are added and inverted by addition operational amplifier _A3 , and as a result, an output voltage V _O exhibiting dead band characteristics as shown in FIG. 5 is obtained at the output terminal of amplifier _A3 . . In Fig. 5, the values of the break points are +R/R ₄ V _B and -R/R ₂ V _B , and the gradients of the linear part are R/R ₃ and R/R ₁ , but normally _R1 = _R2 = _R3
=R ₄ =R is selected.

By the way, when trying to apply the dead zone generation circuit having the basic circuit shown in Figures 2 and 3 to actual equipment, from the viewpoint of handling operation and accuracy, the first step is to input the dead zone width adjustment. Voltage V _IN
One adjustment element (for example, a variable resistor) common to both the positive and negative ranges of It is essential to minimize the number of precision resistors required.

In order to satisfy the first requirement, conventionally, configurations as shown in FIG. 6 (corresponding to FIG. 2) and FIG. 7 (corresponding to FIG. 3) have been adopted. However, according to this configuration, in addition to the configurations shown in FIGS. 2 and 3, dead band adjustment circuits K ₁ and
In addition to having to add K ₂ to each, five precision resistors (resistors R, R,
R ₁ , R ₂ , _{R 3} and R _{4 )} , and in the case of FIG. I couldn't satisfy you enough.

The present invention has been developed in view of the above circumstances, and has realized a highly accurate circuit with a simple configuration that does not depend on resistance accuracy at all. Furthermore, by adding a floating power supply, the dead band width can be reduced using a single adjustment element. The present invention provides a dead band generation circuit that allows positive and negative adjustments to be made at the same time.

An embodiment of the present invention will be described below with reference to FIG.

The dead zone generation circuit shown in FIG. 8 includes an input buffer circuit _A1 that receives the input voltage V _IN that has arrived at the input terminal T _IN , and a resistor _R1 that sets the dead zone for negative input at the output section of this circuit _A1 . An operational amplifier that configures a unipolar circuit to output negative voltage through
A ₂ and an operational amplifier A ₃ forming a unipolar circuit for outputting a positive voltage via a resistor R ₂ with a dead band setting for the positive input at the output section of the circuit A ₁ . The cathode side of a diode _D1 is connected to the output part of this operational amplifier _A2 , and the anode side thereof is connected to the inverting input part of the amplifier _A2 . In addition, a diode D ₂ is connected to the output section of the operational amplifier A ₃ .
The anode side of the amplifier A3 is connected and the other cathode side is connected to the inverting input of the amplifier _A3 . The anode side of the diode D ₁ and the cathode side of the diode D ₂ are connected to the output terminal T _O and further grounded via R _O .

Further, a constant current source I ₁ that causes a constant current to flow in is connected to the non-inverting input portion of the operational amplifier A ₂ , and a constant current source I ₂ that causes a constant current to flow out to the non-inverting input portion of the operational amplifier A ₃ . has been done.

Next, the operation of the dead zone generating circuit configured as above will be explained. When input voltage V _IN is supplied to input terminal T _IN , V _IN +R ₁ I ₁ is applied to the output side of resistor R ₁ through amplifier A ₁ , that is, to the non-inverting input of operational amplifier A ₂ .
A voltage of V _IN -R ₂ I ₂ is obtained at the non-inverting input of the operational amplifier A ₃ . Therefore,
In the range where the input voltage V _IN is greater than -R ₁ I ₁ and less than R ₂ I ₂ , the input voltage of operational amplifier A ₂ is positive, so diode D ₁ is turned off, and the input voltage of operational amplifier A ₃ is negative. Therefore, the diode D ₂ is turned off and the output voltage V _O becomes OV. In the range where the input voltage is less than −R ₁ I ₁ , the operational amplifier A ₂ and
Since the input voltage of A ₃ is negative, only diode D ₁ is turned on, and the output voltage V _O becomes V _IN +R ₁ I ₁ . In the range where the input voltage is greater than R ₂ I ₂ , the amplifier A ₂ and
Since the input voltage of A ₃ is positive, only diode D ₂ is turned on, and the output voltage V _O becomes V _IN −R ₂ I ₂ .

Therefore, as shown in FIG. 9, the relationship between the input voltage V _IN and the output voltage V _O is such that the voltage at the break point is -R ₁ I ₁ .
R ₂ I ₂ yields an output voltage V _O such that the slope of the linear part is 1.

Note that the present invention is not limited to the above embodiments. For example, if a floating variable power supply V _F is used between both non-inverting inputs of operational amplifiers A ₂ and A ₃ instead of a constant current power supply as shown in FIG.
It is possible to simultaneously change the positive and negative dead band widths using individual adjustment elements.

As described in detail above, according to the present invention, it is possible to provide a dead zone generation circuit which has a simple configuration and can output a signal by clearly distinguishing between a dead zone and a sensitive zone without depending on the precision of the resistor.

[Brief explanation of the drawing]

Fig. 1 is a characteristic curve diagram showing dead band characteristics to be obtained by a dead band generating circuit, Figs. 2 and 3 are connection diagrams showing conventional dead band generating circuits, and Figs. 4 and 5 are diagrams of those circuits. A characteristic curve diagram showing the characteristics, FIGS. 6 and 7 are connection diagrams showing the conventional configuration used when applied to the actual equipment shown in FIGS. 2 and 3, and FIG. 8 is a connection diagram according to the present invention. FIG. 9 is a connection diagram showing one embodiment of the dead zone generating circuit, FIG. 9 is a characteristic curve diagram showing its characteristics, and FIG. 10 is a connection diagram showing another example of the present invention. A ₁ to _{A 3} ... operational amplifier, R ₀ , R ₁ , R ₂ ... resistance, D ₁ , D ₂ ... diode, I ₁ , I ₂ ... constant current source, V _E ... floating variable power supply.

Claims (1)

[Scope of utility model registration request] a buffer amplifier to which positive and negative input signals are supplied;
A first resistor for setting a dead band for the negative input, one end of which is connected to the output section of the buffer amplifier, and a second low resistor for setting the dead zone for the positive input, and the other end of the first resistor is the non-inverting input. a first operational amplifier connected to the terminal and having one end of a first diode connected to the output section that operates with a negative input, and the other end of the second resistor being connected to the non-inverting input terminal and outputting. a second operational amplifier to which one end of a second diode that operates with a positive input is connected;
A constant current source or voltage signal generation source of different polarity connected to the non-inverting input terminal of each input section of these first and second operational amplifiers and the other ends of the first and second diodes are common. a third resistor connected to each inverting input terminal of the first and second operational amplifiers and interposed between the common connection end and zero potential, the third resistor having a dead band width equal to or less than the first resistor; and a second resistor, and the linear portion is proportional to the positive and negative input signals that are not affected by the first, second and third resistors.