CN101661817B - High-value Hamon resistor - Google Patents

Abstract

The invention provides an easy-switching-type high-value Hamon resistor, aiming at solving the problem of low measurement accuracy caused by leakage current in the using process of the high-value Hamon resistor. The high-value Hamon resistor comprises two circuit boards, wherein the first circuit board is provided with a series circuit formed by working resistances, and the second circuit board is provided with two leads which are not connected with each other; when the two circuit boards are contacted with each other, the two endpoints of each working resistance on the first circuit board are respectively contacted with the two leads on the second circuit board, so that a parallel connection structure formed by the working resistances can be formed; and when being separated from each other, the two circuit boards are in a mutual independent state. The high-value Hamon resistor can be widely applied to the field of circuit measurement.

Description

A kind of high-value Hamon resistor

Technical field

The present invention relates to Electric Measurement Technology, particularly a kind of measurement Hamon resistor.

Background technology

Hamon resistor is the resistor of one group of substitutional resistance with the work of series and parallel mode, is mainly used in the precision direct current resistance fields of measurement.Concrete principle is as follows: when in parallel, the parallel resistance resistance is approximately equal to the relative deviation of series connection resistance for nR for the relative deviation of R/n with the nominal value resistance R for n.The consistent degree of this n resistance is the key factor of influence resistance relative deviation in parallel and series connection resistance relative deviation consistance degree of approximation.

Below be the mathematical derivation process:

Suppose that n resistance nominal value is R, actual value is R ₁, R ₂... R _n, their arithmetic mean value is R ₀, R ₁=R ₀(1+C ₁), R ₂=R ₀(1+C ₂) ... R _n=R ₀(1+C _n), C _iBe the relative deviation of i resistance, and have

$\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{C}_i=0$

Then the resistance in series actual resistance is R _s=nR ₀

By the nominal value resistance of then connecting is nR, and establishing series connection resistance relative deviation is Cs, and therefore such one group of relation is arranged:

R _s＝n·R(1+C _s)--------------------------------①

Resistance R in parallel _p, equation is as follows:

$\frac{1}{R_p}=\frac{1}{R_0(1+C_1)}+\frac{1}{R_0(1+C_2)}+\·\·\·\·\·\·+\frac{1}{R_0(1+C_n)}=\underset{i=1}{\overset{n}{\mathrm{\Σ}}}\frac{1}{R_0(1+C_i)}$

C _iBe generally value, do series expansion, omit three rank and above a small amount of, obtain less than 0.01%:

$\frac{1}{R_p}=\underset{i=1}{\overset{n}{\mathrm{\Σ}}}\frac{1}{R_0(1+C_i)}\≈\frac{1}{R_0}(n-\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{C}_i+\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{C}_i^2)=\frac{n}{R_0}(1+\frac{1}{n}\underset{i=1}{\overset{n}{\mathrm{\Σ}}}{C}_i^2)$ -------------------------------②

If select C _iFor less than 0.01% resistance, then

Less than 10 ^-8, can omit and disregard, 2. the formula abbreviation is

$\frac{1}{R_p}=\frac{n}{R_0},$

Therefore, R _s=n ²R _p----------------------------------------3.

By nominal value resistance then in parallel be

If resistance relative deviation in parallel is C _p, therefore such one group of relation is arranged:

$R_p=\frac{R}{n}(1+C_p)$ -------------------------------④

Will be 1. and 4. substitution 3. obtain at last:

C _s＝C _p-----------------------------------------------⑤

5. expression formula illustrates at the relative deviation of ignoring the series connection resistance of n resistance under the high-order a small amount of situation and equals resistance relative deviation in parallel.Comprehensively 3. and 5., be called as the Harmon principle.

The consistance of the consistent degree of n resistance and its series and parallel resistance relative deviation be " square " relation, therefore by select consistent degree preferably one group of resistance R can obtain high connection in series-parallel resistance consistance, usually can think that the relative deviation of the resistance in parallel of n resistance R equals the relative deviation of these resistance series connection resistances.

According to the Harmon principle, select n resistance consistance preferably resistance can accurately obtain 1: n ²Perhaps n ²: 1 resistance value proportionate relationship, realize the vast scale transmission of resistance value.Fig. 1 has shown the principle of Hamon resistor, A _iAnd B _iBe two end points of operating resistance, i is a natural number, and shown in Figure 1 is that operating resistance is in series connection, if with whole A _iBe electrically connected, simultaneously with whole B _iBe electrically connected, then operating resistance has been formed parallel circuit.

In normal employing of the operating resistance of Hamon resistor (being the resistance R of above-mentioned formation series and parallel relation), low resistance, and when operating resistance adopted high value resistor (resistance is greater than the resistance of 1 megaohm), the leakage current of existence can cause measurement result bigger error to occur.The reason that high-value Hamon resistor produces leakage current is: existing Hamon resistor is provided with connection terminal (connection terminal is connected with the end points of operating resistance) outside the housing of resistor, and connection terminal hand-manipulated is set up to be electrically connected and made operating resistance realize the series and parallel changing-over.Existing operating resistance series and parallel transition is by manual operations, complicated operation not only, and in time with the increase of number of times, the connection terminal surface can be polluted by the stronger material of electric conductivity, thereby leakage current is strengthened, influence the accuracy that high-value Hamon resistor is measured.

Summary of the invention

In use exist leakage current to cause the low problem of accuracy of measurement in order to solve high-value Hamon resistor, the invention provides a kind of novel easy shifting high-value Hamon resistor, the pollution of avoiding connection terminal to be exposed to causing in the operating environment, thereby effectively avoided the generation of leakage current, improved the accuracy that high-value Hamon resistor is measured.

Technical scheme of the present invention is as follows:

High-value Hamon resistor, described Hamon resistor is that one group of substitutional resistance is with string, the resistor of parallel way work, described high value is meant the resistance of the resistance of described substitutional resistance greater than 1 megaohm, comprise two circuit boards, first circuit board is provided with the series circuit of being made up of operating resistance, second circuit board is provided with two not leads of UNICOM, when two circuit board contacts, two end points of each operating resistance of realizing some operating resistances on first circuit board contact with two leads on second circuit board respectively, the parallel-connection structure that formation is made up of described operating resistance, two circuit boards are in separate state when two circuit boards separate.

Described two circuit boards are arranged in the same airtight housing, and housing is provided with control gear, the contact of two circuit boards of control gear control with separate.

Two end points of each operating resistance lay respectively on the concentric circumferences that two diameters do not wait on first circuit board, two leads on second circuit board are arranged to the concentric circles that two diameters do not wait, when two circuit boards are realized described contact, two concentric circless on second circuit board overlap respectively with two concentric circumferences on first circuit board and contact, and promptly two end points of each operating resistance contact with two leads on second circuit board respectively on first circuit board.

The material of described first circuit board and second circuit board is a teflon.

First the above end points of circuit board and described lead contacting structure are elastic sheet metal, and when two circuit boards were realized described contact, described elasticity shape sheet metal contacted with described lead.

Technique effect of the present invention:

The contact of high-value Hamon resistor of the present invention by two circuit boards with separate parallel connection and two states of series connection of realizing Hamon resistor, loaded down with trivial details operations such as manual grafting joint have been avoided, and the connection terminal that causes is polluted, and then solution high-value Hamon resistance produces the problem of leakage current, improve the accuracy that the high-value Hamon resistor of knowing clearly is measured, realized purpose of the present invention.

Description of drawings

Fig. 1 is the Hamon resistor schematic diagram.

Fig. 2 is the structural drawing of first circuit board of high-value Hamon resistor of the present invention.

Fig. 3 is the structural drawing of second circuit board of high-value Hamon resistor of the present invention.

Fig. 4 is the structural drawing of the high-value Hamon resistor of the present invention that assembles.

Sign is described as follows among the figure:

1, operating resistance; 2, wiring end points; 3, wiring end points; 4, lead; 5, lead; 6, control gear; 7, second circuit board; 8, first circuit board; 9, elastic sheet metal.

Embodiment

Below in conjunction with accompanying drawing technical scheme of the present invention is elaborated.

Fig. 2 has shown the structure of first circuit board of resistor of the present invention, this circuit board is the circular slab face, the some operating resistances 1 of radial distribution on the plate face, and these operating resistances 1 are connected in series on this circuit board, the black round dot is the wiring end points on the circuit of series connection, as the metal column of projecting plate face.The wiring end points is the end points of operating resistance (being also referred to as the pin of operating resistance) just, and each operating resistance all has two wiring end points.On first circuit board, the wiring end points be divided into two groups (identical with the grouping of the end points of operating resistance among Fig. 1, be divided into A group and B group, the code name of same group wiring end points is A or B indexing), wiring end points 2 and wiring end points 3 belong to two groups respectively among Fig. 2, same group wiring end points is positioned on the circumference, and the layout of two set of connections end points has constituted two concentric circless that diameter is different.

What Fig. 3 showed is the structure of second circuit board of resistor of the present invention, and this circuit board is similarly the circular slab face, two leads (lead 4 and lead 5) is set on the plate face constitutes two concentric circless, and the stain that is provided with on the concentric circles is the wiring end points.Two concentrically ringed sizes on second circuit board respectively with first circuit board on two concentric circless measure-alike.When first circuit board contacts with second circuit board, two concentric circless on second circuit board overlap respectively with two concentric circumferences on first circuit board and contact, and promptly two end points of each operating resistance contact with two leads on second circuit board respectively on first circuit board.Wiring end points on second circuit board is corresponding one by one with the wiring end points on first circuit board, promptly the wiring end points on second circuit board can dock (can peg graft by metal column and metallic channel structure between the wiring end points on two circuit boards) with wiring end points on first circuit board, has at this moment realized the state that operating resistance is connected in parallel.

Certainly, main thought of the present invention is that the contact by two circuit boards is reached the wiring end points of avoiding manually pegging graft and caused end points to pollute with separating, and does not limit the arrangement form of operating resistance, as long as can reach this target.Therefore, also can adopt the arrangement form of operating resistances such as rectangle, Fig. 2 and preferred embodiment space availability ratio shown in Figure 3 are better.

The material of two circuit boards of the present invention adopts teflon, and this is different from conventional circuit board material.Use the benefit of teflon circuit board manufacturing to be that this material insulativity is better, be difficult for suction, more help under the high value resistor situation requirement precision.It is fixing that the general circuit plate does not adopt the main cause of teflon to be that element is difficult on circuit board, and board structure of circuit of the present invention is simple, can adopt fixing meanss such as screw, reliable in structure.

The structural drawing of an example of the high-value Hamon resistor that Fig. 4 assembles for the present invention.First circuit board 8 and second circuit board 7 are oppositely arranged.The contact of first circuit board 8 and second circuit board 7 is finished with the control gear that separates dependence control lever 6 and spring formation, control lever 6 is a bent stick, lower-left end with the control lever shown in Fig. 46 is a rotation center, control lever 6 turns clockwise in Fig. 4, and then control lever 6 presses down second circuit board 7 and contacts with first circuit board 8.Opposite with above-mentioned action, control lever 6 is rotated counterclockwise, and has withdrawn from the downforce to second circuit board 7, and then second circuit board 7 rises under spring action, disengages with first circuit board 8.In order further to avoid the influence of external environment, first circuit board 8 and second circuit board 7 are arranged in the airtight housing the high value resistor precision.Wiring end points contacting structure on wiring end points among the embodiment shown in Figure 4 on first circuit board and second circuit board is an elastic sheet metal 9, elastic sheet metal 9 bends to semicircle by the rubber-like sheet metal, contact with first circuit board 8 when second circuit board 7 is descending, the elastic sheet metal 9 that arches upward contacts with wiring end points on second circuit board 7.Because the elasticity that elastic sheet metal 9 has, make in upper and lower shown in Figure 4 makes progress certain limit, elastic sheet metal 9 all can keep in touch with the wiring end points on second circuit board 7, this can reduce the accuracy requirement when first circuit board 8 contacted with second circuit board 7, if promptly first circuit board 8 and second circuit board 7 contacted plate face have certain error, contact simultaneously can not be guaranteed to have a few on two plate faces, also effective parallel circuit can be formed between the operating resistance 1.

Claims (5)

1. high-value Hamon resistor, described Hamon resistor is that one group of substitutional resistance is with string, the resistor of parallel way work, described high value is meant the resistance of the resistance of described substitutional resistance greater than 1 megaohm, it is characterized in that comprising two circuit boards, first circuit board is provided with the series circuit of being made up of operating resistance, second circuit board is provided with two not leads of UNICOM, when two circuit board contacts, two end points of each operating resistance of realizing some operating resistances on first circuit board contact with two leads on second circuit board respectively, the parallel-connection structure that formation is made up of described operating resistance, two circuit boards are in separate state when two circuit boards separate.

2. according to the described high-value Hamon resistor of claim 1, it is characterized in that described two circuit boards are arranged in the same airtight housing, housing is provided with control gear, the contact of two circuit boards of control gear control with separate.

3. according to claim 1 or 2 described high-value Hamon resistors, it is characterized in that two end points of each operating resistance on first circuit board lay respectively on the concentric circumferences that two diameters do not wait, two leads on second circuit board are arranged to the concentric circles that two diameters do not wait, when two circuit boards are realized described contact, two concentric circless on second circuit board overlap respectively with two concentric circumferences on first circuit board and contact, and promptly two end points of each operating resistance contact with two leads on second circuit board respectively on first circuit board.

4. according to the described high-value Hamon resistor of claim 3, the material that it is characterized in that described first circuit board and second circuit board is a teflon.

5. according to the described high-value Hamon resistor of claim 4, it is characterized in that first the above end points of circuit board and described lead contacting structure are elastic sheet metal, when two circuit boards were realized described contact, described elasticity shape sheet metal contacted with described lead.

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