JPS5919374Y2 - voltage setting circuit - Google Patents

Description

[Detailed description of the invention] The present invention is a voltage setting circuit that can vary the voltage level within a predetermined range with respect to the power supply voltage or the output voltage of other circuits using a variable resistor in various electronic circuits. Its purpose is to: ■ Measure the set voltage variations due to variations in the resistance value of the variable resistor used (variations in the voltage within the set voltage range and at a given rotation angle or sliding position of the variable resistor) to reduce as much as possible.

■ The above eliminates the adjustment and correction of the set voltage range, etc. during the manufacture of the target circuit, and also eliminates the need for expensive variable resistors that are produced through selection or special manufacturing processes to ensure that the variation in resistance value is extremely small. Even if you don't use it,
It is best to use a variable resistor that is inexpensive and has normal variations (for example, the variation in total resistance value is ±20%).

■ Especially in circuits that require linearity, the B characteristic (
This will also reduce variations in the linearity of the resistance value with respect to the rotation angle (or slide position) of a variable resistor whose resistance value changes linearly with the rotation angle or slide position.

(2) For example, by using a B-characteristic variable resistor, it is possible to obtain a set voltage characteristic that is linear with respect to the rotation angle (or slide position) and has extremely small variations, if necessary.

This is a distant relative of the above with an extremely simple structure.

Conventionally, there has been a configuration of a voltage setting circuit capable of varying the voltage level as shown in FIG.

In Fig. 1, 1 is the power supply voltage, 2 and 4 are fixed resistors,
3 is a variable resistor for voltage setting, and 5 is a semi-fixed resistor.

In this circuit, a variable resistor 3 is connected in series with fixed resistors 2 and 4 through terminal terminals a and b, respectively, which give a total resistance value, and is connected to a power supply voltage 1. When the dynamic terminal C is rotated or slid to change, the set voltage Vref changes.

Here, the variation in the total resistance value of the variable resistor 3 is normally about ±20%, and even if selection is performed, the range that can be mass-produced at a relatively low cost is at most about ±10%. be.

Even in so-called expensive potentiometers, etc., although their linearity is excellent, the tolerance for variation in total resistance value is usually about ±20%.

On the other hand, for fixed resistors 2 and 4, the tolerance for variation in resistance value is usually about ±5%, and the range that can be mass-produced at relatively low cost is ±0.5 to 1%. It has become a degree.

Therefore, in order to realize the circuit shown in Fig. 1 at a relatively low cost, the variable resistor 3 has a tolerance of ±
20%, fixed resistors 2 and 4 are of ±1%, and in order to adjust the variation of variable resistor 3,
A semi-fixed resistor 5 is used.

However, the circuit shown in FIG. 1 requires adjustment using the semi-fixed resistor 5, which increases the number of steps required to assemble the circuit and increases manufacturing costs.

In addition, this circuit configuration requires special characteristics in order to change the set voltage Vref linearly with respect to the rotation angle (or slide position) of the variable resistor 3, and due to variations in the total resistance value, There were drawbacks such as changes in the characteristics of the set voltage Vref.

FIG. 2 overcomes the drawbacks of the conventional example shown in FIG. 1, that is, the set voltage Vref is changed linearly, and 7 is a B-characteristic variable resistor, and 6 and 8 are semi-fixed resistors.

A set voltage Vref is output from the sliding terminal of the variable resistor 7, and can theoretically take a value proportional to the rotation angle (or slide position).

However, in order to adjust the variation in the total resistance value of the variable resistor 7, semi-fixed resistors 6 and 8 are provided, which increases manufacturing costs as in the case of FIG. 1.

Further, FIG. 3 also shows a conventional example, and its characteristics are almost the same as those in FIG. 2.

Fixed resistors 9 and 10 have small variations, for example ±1.
%, and a semi-fixed resistor 11 is provided to adjust variations in the variable resistor 7.

In this case as well, the manufacturing cost increases as described above.

In the above three conventional examples, variations in characteristics due to variations in the total resistance value of the variable resistor are attempted to be adjusted at the time of manufacturing and assembly using semi-fixed resistors, which has the disadvantage of increasing manufacturing costs.

In addition, semi-fixed resistors are more expensive than fixed resistors, and also have drawbacks in their characteristics, such as deterioration over time.

Conventionally, instead of this semi-fixed resistor, during adjustment, a dial-type variable resistor was used to find the resistance value to be inserted, and then a fixed resistor close to that resistance value was replaced later. In this case, problems such as aging are almost eliminated, but it is necessary to prepare various fixed resistors, and the manufacturing process is greater than when using semi-fixed resistors, resulting in higher manufacturing costs. It had drawbacks such as.

As mentioned above, the conventional voltage setting circuit has various problems and is also a difficult problem in circuit design.

An embodiment of the present invention is shown in FIG.

1 is the power supply voltage (may be the output voltage of another circuit),
12, 13, and 14 are fixed resistors, and the tolerance value KF of the variation in resistance value is the same, for example, ±
It is 1%.

Reference numeral 15 denotes a rotary variable resistor having a resistance change characteristic of B characteristic, which is connected in parallel to the fixed resistor 13 and outputs a set voltage Vref from a sliding terminal.

Tolerable value Kv of variation in total resistance value of this variable resistor 15
For example, it is a standard product with ±20%.

Further, the total resistance value RV of the variable resistor 15 is, for example, 100Ω.
The resistance value R13 of the fixed resistor 13 is calculated using the following formula (%).If the resistance value of the fixed resistors 12 and 14 is R1□''R14=I KΩ, then the variable resistance value 15
If the setting voltage Vref is configured to be the minimum when the rotation angle θ is the minimum (the rotation angle at this time is 0% and the maximum is 100%), the range of change of the setting voltage Vref is If the value of voltage 1 is Vcc (however, R13/RV indicates the parallel resistance value of R13 and Rv), then the following range is 0.2036 Vcc<Vref<0.7964 Vc
c, and assuming that the linearity of the variable resistor 15 is good, it becomes a straight line as shown by the characteristic L1 in FIG.

Here, when the total resistance value Rv of the variable resistor 15 has a variation of ±20%, and the resistance value R1 of the fixed resistor 13
The minimum and maximum values of the set voltage Vref when the rotation angle θ is 0% and 100% when the rotation angle θ varies by ±1% in each case are as follows.

As is clear from this table, the set voltage Vr when the total resistance value Rv of the variable resistor 15 varies by ±20%.
The variation in ef is caused by the resistance value R13 of the fixed resistor 13 being ±
This is smaller than when there is a 1% variation,
The variation in the total resistance value of the variable resistor 15 has been extremely reduced.

In calculation, when the above equation is equal, the variation in the set voltage Vref due to the variation ±Kv% in the total resistance value Rv of the variable resistor 15 and the variation ±KF% in the resistance value R13 of the fixed resistor 13 is calculated. are equal, and the smaller R13 is in the above formula,
Variations in the variable resistor 15 are reduced, and are mostly determined by variations in the resistance values of the fixed resistors 13 and 12.degree. 14.

It is also clear that the smaller the variation in these fixed resistors 12, 13, 14, the smaller the variation in the set voltage Vref.

As described above, in the embodiment shown in FIG. 4, the variation in the total resistance value of the variable resistor 15 is extremely reduced, and it is possible to configure the variation to the extent that it can be almost ignored. By selecting fixed resistors 12, 13, 14 with small variations in resistance value, variations in the set voltage Vref can be made extremely small with a slight increase in material cost.

Furthermore, as is clear from the description, in this embodiment, there is almost no need for adjustment during normal manufacturing and assembly, which greatly contributes to reducing the number of man-hours.

In the above explanation, the resistance values of the fixed resistors 12, 13, and 14 are assumed to have the same variation, but depending on the range of the set voltage Vref, they may not necessarily be the same.
It is possible to make the influence of the variation in the set voltage Vref on the same level with respect to the variation in the resistance value of each fixed resistor by setting the resistance value of the fixed resistor 12.14 to ±1%, the fixed resistor 12.14 to ±2%, etc.

Further, the same applies even if the variable resistor B is not a rotary type but a sliding type.

Next, FIG. 6 shows another embodiment.

16 and 17 are fixed resistors, and 18 is a variable resistor to which a center tap 19 is added.

The other parts are the same as or equivalent to those in Figure 4.

The resistance values of fixed resistors 12, 16, 17, and 18 have the same variation, and fixed resistors 16 and 1
7 have the same resistance value.

Then, the total resistance value of the variable resistor 18 is Rv, and the tolerance value of its variation is ±Kv%, and the resistance values of the fixed resistors 16 and 17 are R16 and R17, respectively, and the tolerance value of their variation is ±KF%. , is configured to have the following relationship.

That is, the resistance values between the terminal terminals a, l) of the variable resistor 16 connected in parallel with the fixed resistors 16 and 17 and each terminal of the center tap 19 are the same as in the case described in FIG. 4 above. It is designed to have the following effects.

Therefore, the rotation angle θ of the variable resistor 18 is 0% and 100%.
% of the set voltage Vref can be considered to be almost the same as in the case of FIG.

However, in general, even if a variable resistor has a specification in which the resistance change characteristic is linear (B characteristic) with respect to the rotation angle θ, there is usually some variation in the linearity.

In particular, in the case of a rotary type, variations in linearity tend to occur, and in some cases, variations of about 5% occur when the rotation angle θ is around 50%.

Therefore, in order to avoid the influence of this variation in linearity, the variable resistor 18 shown in FIG. 6 is provided with a center tap 19 at a position corresponding to the rotation angle θ50%. Similarly to the 100% position, the variation in the set voltage Vref is reduced so that it can vary as linearly as possible with respect to the rotation angle θ.

Here, in FIG. 7, the characteristic L2 is the center tap 19.
Characteristics when not used.

In this characteristic L2, when the rotation angle θ=0% and 100%, the variation in the set voltage Vref is reduced as in the case of FIG. 4, but for example, when the rotation angle θ=50%, the variable resistor Due to the variation in the linearity of 18, the variation in the set voltage Vref becomes large.

Therefore, by using the center tap 19 as shown in Fig. 6, the set voltage Vref at the rotation angle θ = 50% is given to the value at point M, and the variation in this value is the same as when the rotation angle θ = 0% and 100%. It is given almost the same as the variation, and the variation is extremely small.

Therefore, the rotation angle θ is 0〈θ〈50% and 50〈θ〉10
The nonlinearity between 0% and 0% is negligible, and in fact it becomes a straight line, and the rotation angle θ can be regarded as almost a straight line over the entire range from 0 to 100%, and as a result, any rotation Variations in the set voltage Vref at the angle θ are significantly reduced.

Therefore, in the embodiment shown in FIG. 6, both the variation in the total resistance value of the variable resistor 18 and the variation in its linearity can be reduced, and there is a margin in the accuracy of the characteristics of the variable resistor 18 to be used, and it is further improved. Design becomes easier.

In this embodiment, the variable resistor 18 is not only of the rotary type but also of the sliding type as in the case of FIG. 4.

In addition, in the embodiment shown in FIG. 6, there is only the center tap 19 and no other tap terminals, but by using the tap terminal properties of % and %, for example, three fixed resistors of the same resistance value are connected to the variable resistor. A configuration in which devices are connected in parallel may also be used.

In addition, in the case of 40% or 60% tap terminal characteristics, fixed resistors with ratios corresponding to the resistance values between the respective terminals can be connected in parallel. The relationship between the resistance value of a fixed resistor and the tolerance value of its variation with respect to the tolerance value of the resistance value and variation between terminals (the tolerance value of variation in the total resistance value may also be used) is shown in the explanation of Figure 4. It is sufficient to design it so that the relationship shown in equation (4) is satisfied.
By increasing the number of tap terminals in this way, it can be expected that linearity will improve within a certain range.

Further, FIG. 8 shows another embodiment.

In this embodiment, a B-characteristic variable resistor is used to set the set voltage Vref in a polygonal manner with respect to the rotation angle θ, that is, the voltage change rate is configured to vary for each predetermined rotation angle θ range. It is something to do.

In Figure 8, 28, 29, 30, and 31 are fixed resistors with the same tolerance for variation in resistance value, and 32
is a variable resistor having tap terminals 33 and 34 corresponding to positions where the rotation angle θ is 40% and 60%.

In this figure, if the two tap terminals 33 and 34 are not used, the result will be a modification of the above-mentioned figure 4, and the relationship between the rotation angle θ and the set voltage Vref will be as shown by L4 in FIG. Its change characteristics are rotation angle θ = 0 to 10
At 0%, it becomes a straight line.

Therefore, next, connect the two tap terminals 33 and 34 as shown in Figure 8, and connect the four fixed resistors 28, 29, and 30° 31.
When given, a characteristic as shown by L5 in FIG. 9 is obtained.

Characteristic L5 has a rotation angle θ of 0 to 40%. In each section of 40 to 60% and 60 to 100%, the set voltage Vre
The rate of change of f is changing.

That is, while using the B-characteristic variable resistor 32, the rotation angle θ
It is possible to change the rate of change of the set voltage Vref with respect to the voltage Vref, and its characteristics can be freely changed according to the object of use.

In particular, how to determine the fixed resistors 24, 30, 31 is such that each of the adjacent terminals of the variable resistor 32 and the fixed resistor connected in parallel thereto satisfy the above-mentioned formula (4), and Rotation angle θ is 0 to 40%, 40 to 60%, 60 to
The fixed resistor 28 is determined so that the variation width of the set voltage Vref between 100% becomes a predetermined value.

With the configuration shown in FIG. 8 in this way, the variation in the set voltage Vref caused by the variation in the total resistance value of the variable resistor 32 and the resistance value between each terminal will be reduced by the fixed resistor 28, 29, 30, 31. is smaller than the variation in the set voltage Vref caused by variation in each resistance value,
The smaller the tolerance for variation in the resistance values of the fixed resistors 28 to 29 is, the smaller the variation in the set voltage Vref becomes.

Similarly to the configuration shown in FIG. 6, the configuration shown in FIG. 8 can reduce variations in the linearity of the variable resistor 32 at the same time.

Note that this FIG. 8 may include fixed resistors 28 to 3 depending on the case.
In some cases, a predetermined accuracy can be achieved even if the tolerance values for variations in resistance values of each of the resistance values are not the same.

Although FIG. 8 shows that the set voltage Vref can vary from 0 volts, it is clear that it can be configured to vary from a predetermined value other than 0 volts.

Although several embodiments have been described above based on the drawings, the variable resistors used include those whose resistance value change characteristics with respect to rotation angle or slide position are linear (B characteristics), so-called A characteristics and C characteristics. These can also be used depending on the intended use.

Characteristics L6 and L7 in FIG. 10 show exemplary characteristics of the set voltage Vref when variable resistors of A characteristic and C characteristic are used.

In addition, if the tolerance value for variation in the resistance value of a variable resistor or fixed resistor is not given as a percentage for ±, but is given as +20% - 10%, for example, the tolerance value for variation in the above formula (A) is As Kv and VF, the larger one (20% in the above case) may be used.

In addition, the voltage setting circuit according to the present invention can be widely applied, such as providing a single input voltage to an amplifier circuit, etc., as well as providing one input voltage to a differential amplifier circuit or a comparator circuit.
Since the total resistance value of a variable resistor is usually a relatively high value,
As mentioned above, it is desirable to make the input impedance of a circuit that manually sets the voltage as high as possible in order to eliminate its influence.

As described above, the voltage setting circuit based on the present invention has an extremely simple configuration, which minimizes variations in the resistance value of the variable resistor and resistance change characteristics, and enables a highly accurate circuit configuration without adjustment. It can be expected to have various effects such as dramatically improving the degree of freedom of production, being superior in terms of price and mass productivity, and is extremely useful in industrial production.

[Brief explanation of the drawing]

1, 2, and 3 are respectively conventional voltage setting circuits, FIG. 4 is a voltage setting circuit according to an embodiment of the present invention, and FIG.
4 is a characteristic diagram of FIG. 4, FIG. 6 is a circuit diagram according to another embodiment of the present invention, FIG. 7 is a characteristic diagram of FIG. 6, and FIG. 8 is a circuit diagram according to another embodiment of the present invention. FIG. 9 is a characteristic diagram of FIG. 8, and FIG. 10 is a characteristic diagram according to another embodiment of the present invention. 15, 18.32...variable resistor, 19...
...Center tap, 33.34...Tap terminal.

Claims (3)

[Scope of utility model registration request] (1) A plurality of fixed resistors are connected in series to a power supply or a voltage source, a variable resistor is connected in parallel to at least one of the fixed resistors, and a set voltage is output from the sliding terminal. At the same time, the resistance value (or sum of resistance values) RF (Ω) of the fixed resistor connected in parallel with the variable resistor and the tolerance value of its variation ±KF (%
), and the total resistance value Rv (Ω) of the variable resistor and its tolerance value ±KV (%) of the voltage number v constant circuit having the relationship such that RF - Rv -. (2) two terminal terminals that give the total resistance value of the variable resistor;
The voltage setting according to claim (1) of the utility model registration, wherein each adjacent terminal of at least one tap terminal giving a resistance value of a predetermined ratio is connected to both ends of a corresponding fixed resistor. circuit. (3) The relationship between adjacent terminals of a variable resistor and the corresponding fixed resistor between the terminals determines the resistance value between the terminals, Rv' (Ω), and its variation (or variation of all resistors). When the allowable value of is ±Kv' (%), the resistance value of the fixed resistor corresponding between the terminals is Rt'' (Ω), and the allowable value of its variation is ±KF' (%), RF' - Rv Practical Kv' having the relationship: '·1L.' The voltage setting circuit according to claim (2).