HU176711B - Plane electric resistor of high accuracy and adjustable value,and method to adjust the resistance - Google Patents

Abstract

1. A high-precision flat electric resistor having an adjustable resistance value and comprising a sheet of metal or metal alloy deposited on or bonded to a support comprising several electric, resistive, sinuous and interconnectable circuits, each of them being constituted by a series of electrical resistance filaments separated by grooves, some of the said resistive circuits being short-circuited by conductive strips of the metal or metal alloy of the sheet, these circuits being interconnectable by means of cut-out portions made in the conductive strips, the resistance value of a resistor having n electric circuits interconnected in serie being RTn and that of a resistor having n-1 electric circuits interconnected in series being RTn-1, characterized in that the ratio DELTA R = RTn - RTn-1 to the resistance value RTn-1 follows the relation : DELTA R/RTn-1 = 1.3...2n-1/2.4...2n K**2n where K is an adjustable numerical coefficient having a value smaller than 1.

Description

FIELD OF THE INVENTION The present invention relates to a planar electrical resistance of high precision and adjustable resistance, and to a method for adjusting the ohmic resistance of this electrical resistor.

High-precision electrical resistors 5, which are produced electrolytically or by ion bombardment from a metal or alloy layer formation having a plurality of resistive sections separated from one another, are already known. Resistors of this type and methods for producing resistances are described in French Patent Nos. 76,07889 and 76,17269.

The known processes allow for the production of a curved network and a long network of resistors. The resistance sections formed in the metal or alloy layer have a thickness less than a few microns and thus have a very high resistance per unit area.

After series production, these resistors must be set to a specified resistance value of 50-150% above the initial resistance value.

In the prior art, this adjustment is made by providing interruptions 25 between the resistor edge and the resistor section dividers, which switch on a certain number of resistor sections into the circuit so that its resulting resistance value increases. This adjustment procedure is very complicated and must be performed under a microscope with a scratch needle 30 or a sandblast or laser. The setup process is time-consuming as it often requires a very large number of interrupts. For example, to reset a resistor 23 Kohm to a resistor value of 42 Kohm, it is necessary to create an interrupt 102 in the resistor network.

The present invention provides a resistor network that can be set up faster and more conveniently than prior art solutions.

The invention thus provides a high precision and adjustable resistivity with a layer of metallic or alloy material on a flat electrical resistance substrate, the layer comprising curved resistor networks of discrete resistor sections, and wherein the electrical resistor comprises a series of resistor networks short-circuited by metal or alloy material is the quotient of the resistance resistance AR occurring when each electrical resistor network is connected in series and the resulting resistance value RT _n .j after the connected network resistance (n-l) is

AR satisfies the relation where U _{n is} the nth member of a Cauchy's absolute convergent series, and AR = RT _n -RT _n -j.

In order to set the resistance value, interrupts are inserted in series that resistor networks corresponding to the correction resistance value.

It has been found that by selecting the AR resistor increments of the present invention, the number of interrupts required to adjust the electrical resistor can be significantly reduced compared to known solutions.

In a preferred embodiment of the electric resistor according to the invention

RT _n _i 2 · 4. . . 2n where K is less than one constant.

In another preferred embodiment, the carrier has a thermal conductivity of greater than or equal to 96% pure aluminum. This ensures that there is no large temperature gradient between the various resistance sections.

The invention further provides a method for adjusting the ohmic resistance value of an electrical resistor according to the invention by interrupting conductive bands which short circuit the resistor networks. The process is characterized by first interrupting the short-circuit conductor band of the resistor network that causes the increase in resistance as close as possible to the required correction resistance value, and then interrupting the setting by resolving the short-circuit of the resistor network that causes ever less resistance.

According to the invention, only one interrupt is required per resistor network such that the total number of interrupts is not greater than the number of resistor networks. Furthermore, since each resistor network generally consists of a plurality of parallel resistor sections of relatively large lengths, the interruption requires much less precision than the known methods.

It is also desirable to have a serial number and a dividing line between the serial number and the resistor network in the said guide bands, at the same time as the resistor networks are formed. Then, to set the final value of the resistance, said interruption must be made between the edge of the disk and the serial number.

These sequential numbers greatly facilitate the identification of each rescue network and the completion of interruptions.

The invention will now be described with reference to the embodiments illustrated in the drawings, wherein:

Figure 1 is a schematic top plan view of a resistor according to the invention, a

Figure 2 is an enlarged detail of Figure 1.

Figure 1 shows a flat electrical resistance formed of a square layer of a few micron thick metal alloys such as nickel chromium. The electrical resistance shown can be produced in a manner known per se, for example electrolytically or by ion bombardment, by means of a mask defining the shape to be formed.

Layer 10 is applied to, or based on, an insulating substrate (not shown) having a thermal conductivity of greater than or equal to 96% pure aluminum.

In Fig. 1, for the purpose of illustration, the conductive resistor sections 11 are located between parallel lines 12, which represent dividing furrows or notches. The actual design is shown in magnified figure 2.

As shown in Fig. 1, the resistor consists of a plurality of parallel resistor sections 11 which are long, winding and high in resistance per unit area! form a resistance network.

The layer 10 is a series of _ls A _2, A _{3, B,} B ₂ B _{3 is>} C, ₈ ..C C _2, D ₂ ... D D _ls, whose internal resistance network formed by the relationship AR corresponds ellenállásnövekménye at:

AR where U _{n is} the nth member of an absolute convergent series in Cauchy's sense and

AR = RT _n -RT _n -i ·

RT _{n is} the resulting ohmic resistance value after the series n of the resistor network, and RT _n _ _t is the resulting ohmic resistance value after the series of the resistor network (nl).

It can be seen from Figure 1, that Aj resistor network comprises a plurality of resistance section 11 as the _two resistor networks, and the number of these sections of the resistor 11 is greater than the A ₃ ellenálláshálózaté etc.

The convergent series can be as follows:

AR 1 · 3. . . 2n-l __ — __________ =

RT _n -1 2 · 4 ... 2n where K is less than one constant.

The convergent series used can be, for example, a geometric series.

As shown in Figure 1, during manufacture, the sides A, B, C, D of the layer 10 and each of the layers A 1, ..., B 1, 1, 2 .., Ci, ..., Di resistor networks include conductive bands 13, 14, 15, 16, 17, 18 which short circuit the corresponding resistor network.

Consequently, the initial ohmic resistance RT _{0 of} the electrical resistor after manufacture and before adjustment is derived from those resistor networks which do not belong to the aforementioned short circuit resistor A, .., Bi, ..., _Ct , ..., D]. .

When setting the desired resistance value of an electrical resistor, the short circuit of the edge resistor whose resistance value is closest to the required correction resistance value is interrupted first, and then the short circuit of resistor networks causing less and less resistance increase is interrupted.

These interrupts are generated 19 interruptions (Figure 2) by creating applied to the conductor 13, 14, 15, 16, 17, or 18 lanes, which breaks the layer 10 A, B, C or D side and the right, for example, the _three resistor network between them. The interruption 19 is made in a manner known per se, for example by a scratch needle, a sandblast, or a laser.

In order to adjust the resistances in a sufficiently large range according to the invention,

The value of RT _{O is} chosen close to two, where RT _{0 is} the initial resistance value and RT _n is the resulting resistance value when all resistor networks are connected in series.

As shown in Figures 1 and 2, the conductor lanes 13, 14, 15, 16, 17, 18 have serial numbers 1, 2, 3, ... 9, as well as 20 interrupts, the latter being the serial number and between a suitable resistor network, for example A ₃ .

Consequently, the resistance value setting sufficient to indicate the number of the activate resistor networks, and these layers 10 corresponding, for example, the sides and the right, for example an interruption, e.g., 19 interrupt established between three numbered for _three resistor network.

In the preferred embodiment illustrated in Figure 1, A1, ..., _B1s . . Cj, ..., D ₁ ,. . , resistor networks are grouped into four rectangular blocks 21, 22, 23, 24 arranged along layers A, B, C and D of layer 10, respectively.

The following are some numerical examples.

Example 1

This example illustrates a possible alignment rule applicable to the method of the invention.

With the electrical resistance set up, there are twenty-three setting points and the value of the M multiplier is close to 2. The multiplication factor and the ratio of the resistance values between each set-up operation can be set. The ratio of resistance values is as follows:

^AR - ¹ _Kln RT _n _! 2 · 4, .. 2n where K = 0.82.

For the initial resistance value RTo = 15 kohm, the values given in the table below are given.

Counter-Adjustment PRICE ¹ RT _n .] PRICE RTO PRICE [ohm] view network operation number 5 Aj 1 0.336 0.336 5040 a ₂ 2 0.169 .226 3390 10 ₃ 3 0,095 0.143 2145 bi 4 0,056 0.090 1350 b ₂ 5 0,034 0,056 840 15 b ₃ 6 0,021 0,035 525 ci 7 0,013 0,022 330 20 c ₂ 8 .0082 0,014 210 c ₃ 9 0.0052 0,009 135 c ₄ 10 .0033 0,006 90 25 C ₅ 11 0.0021 0.0036 54 C ₆ 12 0.0014 0.0024 36 30 C ₇ 13 0.0009 0.0016 24 C ₈ 14 0.0006 0.0010 15 di 15 0.0004 0.00070 10.5 35 D ₂ 16 0.00024 0.00042 6.3 d ₃ 17 0.00016 0.00028 4.2 40 d ₄ 18 0.00010 0.00017 2.55 D _s 19 0.00007 0.00012 1.80 But 20 0.000045 0.000079 1,185 45 D ₇ 21 0.000029 0.000051 0.765 d ₈ 22 0.000019 0.000033 0.495 50 d ₉ 23 0.000012 0.000021 0,315 When all resistor networks is in line on, that is, all twenty-three interruptions

set up, the set maximum resistance is 55 15,000 ohms + 14,212.11 ohms = 29,212.11 ohms, i.e. the multiplication factor is M = 1.9474.

Example 2

In this case, with an initial resistance value of RT ₀ -15kohm, the resistance of each resistor network corresponds to Example 1. The resistance value to be set is 25,000 ohms ± 0.1%. Thus, the initial resistance value 65 must be increased by a value between 66.51% and 66.83% so that the resistance is within the specified + 0.1% tolerance range.

To do this, first turn on the resistor network that is as close as possible to the given percentage. In this example, the resistance networks A _t and A _{2 provide} 33.6% and 22.6% increase in resistance, respectively. So in these resistor networks we create an interrupt. Then proceed as follows:

Bj resistance network 9%,

C ₂ resistor network 1.4%, © i resistor network 0.07%.

In this way, a total resistance increase of 66.67% was obtained. Thus, according to the invention, the desired setting was achieved with only five interruptions.

If even the :. even more fine-tuning of the resistance value is required, and additional networks of lower resistance value can be switched on.

Example 3 (Comparative)

If the initial and final values and the tolerance range given in Example 2 are adjusted using the known procedure, twenty-seven steps are required to adjust.

The invention is, of course, not limited to the examples and embodiments shown.

The electrical resistance can be adjusted in a manner known per se using a Wheatstone or Kelvin bridge and a digital voltage meter. You can also use a computer that stores each Aj,. · ·, B _1; . . , C _1; . . ., Di,. . ., the resistance value belonging to the resistor network. The program can provide: either indicating to the operator, by means of a digital micro display, the number of interrupts to be generated when the operator is viewing the electrical resistance through a microscope, or controlling an XY board carrying a known automated device (sandblast or laser) suitable for creating the desired interrupts. The latter can be accomplished by the fact that the resistor networks 1, 2, 3,. . . the number of the serial numbers is relatively small and their size is large enough to allow said equipment to be controlled to the correct position.

Due to the use of indicative sequences and the sequential numbers and A, B, C, respectively. The guide bars are located between the sides D, and the adjustment according to the invention can also be performed by simply scraping the guide bar next to the serial number.

Thus, the present invention greatly simplifies the preparation of precision flat electrical resistors.

The invention further reduces the likelihood that a defective resistor network is switched on during setup, and thus provides greater reliability during manufacture than in prior art solutions.

Claims (6)

Patent claims: 1. A high precision and adjustable resistor having a layer of metallic or alloy material on a flat electrical resistance substrate, wherein the layer comprises curved resistor networks of discrete resistor sections, and wherein the electrical resistor comprises a series of resistor networks short-circuited by metal or alloy material, the increment of the PR resistance and the (nl) th network of some electrical resistor networks (Ai, A ₂ ..Bj, B ₂ , .., Ci, C ₂ , .., Dj, D _2. ) is the quotient of the resulting RT _n PR satisfies the relation where U _{n is} the nth member of an absolute convergent series in Cauchy's sense, and PR = RT _n -RT _nl . An electric resistor according to claim 1, characterized in that PRICE 1 · 3. . . 2n-l _____ IC n RT _n _i '2 · 4 ... 2n where K is less than one constant. An electrical resistor according to claim 1 or 2, characterized in that the metal or alloy layer (10) is square or rectangular and the resistor networks (A ₁ , A ₂ , ..., Bi, B ₂₎ , ..., Cj, C ₂ , ..., Dj, D ₂ , ...) are grouped into four separated rectangular blocks (21, 22, 23, 24), which are blocks (21, 22, 23). 24) are formed along each side (A, B, C, D) of the layer (10). An embodiment of an electrical resistor according to claim 3, characterized in that the resistor networks of each array ( ₂₁ , ₂₂ , ₂₃ , 24) are (A ₁ , A ₂ , ..., B ₁ , B ₂ , ... C 1). , C ₂ Dj, D ₂ , ··) are denoted by a number not more than nine in the guiding band (13, 14, 15, 16, 17, 18) between the resistance network and the side of the layer. 5. The electrical resistance of claim 1, wherein the heat transfer coefficient of the substrate is greater than or equal to that of 96% pure aluminum. The method of adjusting the ohmic resistance value of an electrical resistor according to claim 1, wherein breaking the resistor networks with a short-circuit conductor is characterized by first interrupting the short-circuit guide band of the resistor network that causes the increase in resistor as close as possible to the required correction value. and then interrupting the short circuit of the resistor networks that cause a slight increase in resistance.