EP2920798B1 - Planar transformer - Google Patents

Description

The invention relates to a planar transformer with a primary winding, with a secondary winding, with a coupling winding and with a conductor substrate which is the carrier of one or more magnetic core rings.

the U.S. 8,022,802 B2 relates to a sensor for measuring electrical parameters in a high-voltage environment and includes isolation transformers in several embodiments, including an embodiment with a single main circuit board for a plurality of windings arranged side by side, which are magnetically linked via magnetic core rings, and another embodiment with a main circuit board, a Sub circuit board and two magnetic core rings passing through openings of the main and sub circuit boards. The primary winding and the secondary winding are located in and on the main circuit board, while the coupling winding for coupling the two magnetic core rings is arranged on the secondary circuit board. There is some clearance between the two circuit boards and the coupling winding on the slave circuit board is also spaced from the respective edge of the openings in the magnetic core rings. In this way, relatively large toroid openings are required in the magnetic core rings.

With another transmitter ( DE 10 2005 041 131 A1 ) the ferromagnetic cores are wound to form coils, with the windings of the coils on different ferromagnetic cores are attached in order to comply with the required insulation distances. The ferromagnetic cores are magnetically coupled to each other via an additional winding embedded in a printed circuit board. Because of the necessary winding of the ferromagnetic cores, a transformer constructed in this way can only be manufactured at high cost.

Out of U.S. 2011/0140824 A1 a transformer is known in which windings which are to be separated in terms of potential are mounted asymmetrically on different printed circuit boards which are stacked one on top of the other and connected to the transformer with a two-part ferromagnetic core.

In U.S. 2011/0095620 A1 describes a planar transmitter for miniaturized applications, the coil windings of which are arranged on opposite sides of an insulating substrate. The device works on the basis of induction, without ferromagnetic cores.

Out of EP 0 715 322 A1 a transducer manufactured using planar technology is known, in which conductor tracks are accommodated in layered layers in a printed circuit board and thus form transformer windings. A ferromagnetic core surrounds the transformer windings with annular legs on the outside and a cylindrical leg on the inside.

Out of DE 20 2009 002 383 U1 a planar transformer is known that contains a multi-layer circuit board, the high dielectric strength of the circuit board layers with each other, between the primary and the secondary windings, guaranteed. The transformer can be controlled potential-free with opposing signals. A signal to be transmitted in the positive direction of magnetic flux of a common primary winding or of a single primary winding immediately generates a positive control signal in a first secondary winding in the same coupling direction. A signal in the negative magnetic flux direction of a second or the same winding immediately generates a positive control signal in a second secondary winding in the opposite coupling direction to the first secondary winding, or a negative control signal in the first secondary winding, and if no further signal is to be transmitted, this takes place automatic or digitally controlled demagnetization of the transformer by circuit elements by one or two windings controlled as a short circuit immediately at the end of a previously transmitted signal.

DE 10 2009 037 340 A1 shows a transformer in which wound, ring-shaped cores are connected via a short-circuit winding. The short-circuit winding is connected, for example by soldering, to corresponding contacts on a printed circuit board.

The invention is based on the object of specifying a planar transformer which is easy to manufacture and which enables potential separation for two or more potential groups in the smallest of spaces. The object is solved in each case by the subject matter of independent claims 1 and 2.

The new planar transmitter has at least two ferromagnetic cores and one provided with yoke legs single, plate-shaped conductor substrate for forming a primary winding and at least one secondary winding, which are coupled to one another by at least one coupling winding. The conductor substrate forms a plate-shaped carrier for the ferromagnetic cores, which are divided to form yoke core halves that can be assembled and have at least two yoke legs that reach through, which can be inserted through recesses in the conductor substrate in order to form a magnetic core ring by closing the yoke core halves.

In order to achieve a potential separation between the primary winding and the secondary winding in the smallest of spaces, one has to accept that the magnetic core rings only maintain small separation distances from the plate-shaped conductor substrate, which closes parts of the primary winding in the area of a first ring core opening and parts of the secondary winding in the area of a second ring core opening the surface of the conductor substrate receives. In terms of potential, the relevant magnetic core ring is thus added to the adjacent primary winding or secondary winding, although of course an insulating layer known as functional insulation separates the relevant winding from the ferromagnetic material of the at least two magnetic core rings, which are arranged at a distance and are electromagnetically linked to one another via the coupling winding, but at different potentials (the Primary winding or the secondary winding) lie. Thus, the coupling winding must maintain a sufficient insulation separation distance to adjacent inner sides of the toroidal openings and to adjacent turns of the primary winding and secondary winding, so that the Potentials can be separated from each other by an overall isolation distance. This total insulation separation distance can be divided among the respective separation distances between the coupling winding and the ring core opening or adjacent turn of the primary winding or secondary winding, although a respective minimum separation distance must be observed.

In a first design, one leg of the magnetic core ring accommodates the primary winding, while the other leg is wrapped by a first portion of the coupling winding, which also wraps with a second portion of the leg of an adjacent toroidal core, the other leg of which accommodates the secondary winding. Multiple secondary magnetic core rings provided with secondary windings can be coupled to a single primary magnetic core ring.

In a second design, a first leg of the two magnetic core rings is wrapped by two windings in different layer levels of the conductor substrate, with the coupling winding connecting the two magnetic core rings and the primary winding being assigned to one magnetic core ring, while the secondary winding is assigned to the other magnetic core ring. If a respective second leg of the two magnetic core rings in one of the different layer planes of the conductor substrate is free of the windings mentioned, an auxiliary winding can be arranged there, for example for control purposes. But it is also possible that Primary winding or the secondary winding continue with a section on the free leg.

Because the magnetic core rings are designed as two-part yoke cores and the windings, including the coupling winding, are designed as integral parts of the plate-shaped conductor substrate, the manufacture of the planar transformer is simplified, since the legs of the yoke cores only need to be inserted through cutouts in the plate-shaped conductor substrate and each need to be completed to form a magnetic core ring. At the same time, this design enables good space utilization of the ring core opening with simultaneous electrical isolation between adjacent magnetic core rings.

Fig. 1

eine erste Bauform eines Übertragers in Planarbauweise in schematischer Draufsicht,

Fig. 2

den Übertrager von Fig. 1 gemäß Schnitt A-B,

Fig. 3

eine zweite Bauform eines Übertragers in Draufsicht und

Fig. 4

gemäß Schnitt C-D,

Fig. 5

einen Übertrager mit zwei Sekundärwicklungen in Draufsicht und

Fig. 6

gemäß Schnitt E-F,

Fig. 7

einen weiteren Übertrager mit zwei Sekundärwicklungen in Draufsicht,

Fig. 8

einen weiteren Übertrager in schematischer Draufsicht und

Fig. 9

gemäß Schnitt G-H,

Fig. 10

eine Variante des weiteren Übertragers nach Fig. 8, 9 in schematischer Draufsicht,

Fig. 11

einen weiteren Übertrager mit Koppelwicklung oberflächennah in schematischer Draufsicht und

Fig. 12

gemäß Schnitt I-J,

Fig. 13

einen weiteren Übertrager mit E-förmigen Kernhälften in schematischer Draufsicht und

Fig. 14

gemäß Schnitt K-L.

Embodiments of the invention are described with reference to the drawings. show:

1

a first design of a transformer in a planar design in a schematic top view,

2

the transmitter of 1 according to section AB,

3

a second design of a transformer in top view and

4

according to cut CD,

figure 5

a transformer with two secondary windings in top view and

6

according to section EF,

7

another transformer with two secondary windings in top view,

8

another transformer in a schematic top view and

9

according to section GH,

10

a variant of the further transformer Figures 8, 9 in schematic top view,

11

another transformer with coupling winding close to the surface in a schematic plan view and

12

according to section IJ,

13

another transformer with E-shaped core halves in a schematic plan view and

14

according to section KL.

Figures 1 and 2 represent a first embodiment of a transformer according to the invention in planar construction. The main parts of the transformer are a primary winding 1, a secondary winding 2, a coupling winding 3, a first two-part magnetic core ring 4, a second two-part magnetic core ring 5 and a single plate-shaped conductor substrate 6. The magnetic core rings 4, 5 each comprise two yoke core halves 41, 51 and 42, 52, which close to form the ring 4 with the first ring core opening 43 or the ring 5 with the second ring core opening 53. The magnetic core rings 4, 5 each have reach-through legs 44, 45 or 54, 55 and connecting legs between the reach-through legs. The leg 44 or 54 can belong to one or the other core half 41, 42 or 51, 52, or can also be divided, as in 9 shown. The plate-shaped conductor substrate 6 has two pairs of recesses 61, 62 and 63, 64, which form openings for the reach-through legs 44, 45 and 54, 55 of the magnetic core rings 4, 5. The pairs 61, 62 and 63, 64 of the recesses are separated from one another by an insulating gap and accommodate the reach-through legs 44, 45 or 54, 55 of the magnetic core rings 4, 5. The primary winding 1 surrounds the recess 61 in several Layer levels of the conductor substrate 6, of which four layer levels 11, 12, 13, 14 are indicated here and which extend on the surface of the conductor substrate, or near the surface, and in the conductor substrate interior. The conductor substrate 6 almost fills the toroidal openings 43 and 53, respectively.

As in 1 indicated, the primary winding 1 assumes a spiral course in each layer plane. The four spiral forms are interconnected to form the primary winding 1. Similarly, spiral forms of the secondary winding are present in four layer planes 21, 22, 23, 24 and surround the recess 64.

The coupling winding 3 wraps around the reach-through limb 45 with its partial area 34 and the reach-through limb 55 with its partial area 35 and is self-contained in the sense of a short-circuit winding, i. H. forms a ring of wires. The coupling winding can be arranged in two layer planes 31, 32 and is surrounded on all sides by an insulating layer with a thickness that results in a partial insulating separation distance of L/2. In this case, "L" means the overall insulation separation distance, which is calculated from the plate thickness of the conductor substrate 6 minus the distance between the layer planes 31, 32 from one another. The layer levels 12, 13 and 22, 23 are separated from one another by an insulating layer which is referred to as "functional insulation".

Through the mediation of the magnetic core rings 4, 5 and the coupling winding 3, the primary winding 1 and the Secondary winding 2 coupled to each other with galvanic isolation in the total isolation distance L.

The magnetic core rings 4 and 5 with their core halves 41, 42 or 51, 52 surround the respective ring opening 43 or 53. The core halves can be the same or different and can be composed of different geometric shapes. The cross sections can be rectangular, rounded, round or oval. Air gaps can be provided between the core halves, but it is also possible to largely close the air gaps if the core halves are assembled by gluing or clamping. Specifically, the core halves can take U, I, and E shapes.

As in 1 shown, the layers of the primary winding 1 occupy approximately half of the cross-sectional area of the ring opening 43, while the layers 31, 32 of the coupling winding 3 occupy the other half of the cross-sectional area of the ring opening 43. Partial insulation separation distances of L/2 both to the yoke legs and to the primary winding 1 are maintained.

The same situation is found with regard to the secondary side. Here, too, the layers of the secondary winding 2 take up approximately half of the cross-sectional area of the annular opening and the coupling winding 3 has partial insulation separation distances of L/2 from the edge of the opening or from the layers of the secondary winding. In this way there is a potential separation between the primary winding 1 and the secondary winding 2 with a total isolation distance 2·L/2 = L, which is chosen at least as large as required by the standard EN 60079-11, i.e. the minimum total isolation distance, or more.

The coupling winding 3 is constructed isolated from all other potentials. As a result, the isolation distance L can be built up in two partial isolation distances. The total isolation distance L can also be divided in a different way to the division L/2+L/2. To meet the requirements of EN 60079-11, the smaller partial isolation distance must be greater than L/3. As can also be seen from the drawings, no large insulation distances need to be maintained from the primary winding 1 or secondary winding 2 to the associated magnetic core ring 4 or 5. The functional insulation mentioned is often sufficient, so that the individual turns of the windings are not bridged by the adjacent connecting legs. The magnetic core rings can therefore be assigned the same electrical potential as the windings.

The insulating separation distance between the adjacent magnetic core rings 4 and 5 is selected to be sufficiently large so that the magnetic core rings maintain their respective different potentials during operation of the transformer. If the primary and secondary windings do not maintain large insulating distances from the associated magnetic core rings, this means that a large part of the cross-sectional area of the ring opening 43 or 53 can be used for the turns of windings 1 or 2, and this space gain means a larger number of turns on the same Surface and thus the achievement of a higher inductance compared to the case where the windings are not allowed to reach the edge of the ring openings. The new planar transmitter is therefore suitable for miniaturization.

the Figures 3, 4 show a variant of the transformer Figures 1, 2 , The inner layer of the plate-shaped conductor substrate 6 being used only for the coupling winding 3, which is also separated from all other potentials by half the insulating separation distance L/2. The primary winding 1 and the secondary winding 2 are on the top and bottom of the conductor substrate 6, or close to the surface in overlapping with the portions 34 and 35 of the coupling winding 3. Compared to the embodiment Figures 1, 2 the ring opening 43, 53 can be smaller compared to the embodiment Figures 1, 2 be carried out, but at the expense of the number of turns of primary and secondary winding.

Figures 5 and 6 show a variant of the transformer with two secondary windings. Accordingly, there are two secondary magnetic core rings 5a, 5b and two secondary windings 2a and 2b as well as a coupling winding 3 with two "ears" or branches 36, 37. The legs of the magnetic core rings penetrate the conductor substrate 6 at the openings 61, 62, 63a, 63b, 64a, 64b. Otherwise the details correspond to those of the transformer Figures 1 and 2 . But it can also be the details of how to Figures 3 and 4 described, applied. When building the transformer Figures 5, 6 the outputs of the secondary windings 2a, 2b are independent of each other. The respective output voltage depends on the transformation ratio of the primary winding to the respective secondary winding, ie the outputs are connected in parallel. If an output is not used, current can still be drawn from the other output.

7 shows another variant of the transformer with two secondary windings 2a, 2b. For this variant, three magnetic core rings 4, 5a, 5b and a coupling winding 3 are used, which links all three magnetic core rings 4, 5a, 5b together. The legs of the magnetic core rings penetrate the conductor substrate 6 at the openings 61, 62, 63a, 63b, 64a, 64b. The outputs of the two secondary windings are not independent of each other in terms of function, since they are in series in the equivalent circuit diagram. This means that in the ideal case, a current can only flow at both outputs at the same time.

Figures 8 and 9 show a design of the transformer in which each of the magnetic core rings 4, 5 has a leg 44 or 54 wrapped around by two windings. The primary winding 1 and the portion 34 of the coupling winding 3 wrap around the leg 44 , while the secondary winding 2 and the portion 35 of the coupling winding 3 wrap around the leg 54 . Leg 45 parallel to leg 44 and leg 55 parallel to leg 54 are thus free and can, for example, carry an auxiliary winding which can be used for control purposes. How out 9 As can be seen, the primary winding 1 and the secondary winding 2 are on the top and bottom of the conductor substrate 6, or close to the surface and partially overlapping with the partial areas 34, 35 of the coupling winding 3, which can be arranged in two layers 31, 32.

10 shows a variant of the embodiment Figures 8, 9 . The legs 44, 45 and 54, 55 of the two magnetic core rings 4 and 5 are each covered with spiral winding sections 15, 16, 17, 18 and 25, 26, 27, 28, respectively. The winding section 15 forms left-handed spiral turns on the upper side of the conductor substrate 6 and pierces the conductor substrate in a via in order to again form left-handed spiral turns on the underside of the conductor substrate 6, which are largely covered by the winding section 15 in the drawing and are therefore in the drawing can only be seen in traces. The winding section 16 is conductively connected on the underside to the winding section 17, specifically to the outer wire turn of the winding section 17. The line is routed to the upper side of the conductor substrate 6 by means of a via, where the clockwise spiral windings continue up to the line terminal on the outer edge of the conductor substrate 6 . The shapes of the secondary winding 2 are mirror images of the shape of the primary winding 1. The coupling winding 3 extends in a layer plane inside the conductor substrate 6, corresponding to the illustration in FIG 9 .

the 11 and 12 show an embodiment of the transformer in which the coupling winding 3 is on the top and bottom of the conductor substrate 6 and thus has the same potential as the magnetic core rings 4, 5. An isolation distance between the magnetic core rings is not necessary. The primary winding 1 and the Secondary winding 2 runs in the inner layers of the conductor substrate, each with half an insulating separation distance from the magnetic core rings 4, 5 and from the coupling winding 3. The core halves 41, 42 and 51, 52 are designed, for example, in a U-shape. Here, as in the other embodiments, the magnetic core rings can be assembled in other ways than shown, and each half can consist of more than one piece. For example, four leg rods can be joined together to form a magnetic core ring.

the 13, 14 show an embodiment of the transformer with E-shaped core halves 41, 42, which form a central web corresponding to the leg 44 when combined, which extends through the opening 61 in the conductor substrate 6. The other magnetic core ring 6 also has such a central web to form the leg 54 . The leg 44 is surrounded by the primary winding 1 and the leg 54 by the secondary winding 2 spirally in two layer planes 11, 14, similar to that in FIG 9 is shown. The coupling winding 3 with its sections 34, 35 forms a closed loop around the two middle webs of the magnetic core rings. This can take place in two layer levels 31, 32 within the conductor substrate 6. FIG.

Because of the E-shape of the core halves 41, 42 or 51, 52, three openings 61, 62a, 62b or 64, 63a, 63b are required in the conductor substrate 6 in each case. Any two of these openings are regarded as pairs within the meaning of the following patent claims. The embodiment after 13, 14 corresponds functionally to the embodiment Figures 8, 9 . It can but also a construction according to 10 be used, with the third leg 46 or 56 still being available for an auxiliary winding. Also you could for the yoke legs 44, 45 and 54, 55 according to the construction Figures 1, 2 use with free legs 46, 56 for replacement purposes. Finally, one could also connect two or three primary windings and corresponding secondary windings, e.g. B. for the purpose of failure replacement, combine.

The plate-shaped conductor substrate 6 in all of the embodiments is preferably produced as an electronic circuit board. However, production as a sprayed substrate is also possible. The transformer can be produced both as an individual component with a separate printed circuit board, in which case this component then has to be assembled on a main printed circuit board, and integrated directly into a main printed circuit board.

Further variants can be added to the variants described. For example, it is possible to provide the primary winding and/or the secondary winding with one or more center taps.

The transformer is made as follows:
Two-piece yoke-leg ferromagnetic cores are provided as described and illustrated. The ferromagnetic cores contain two halves 41, 42 or 51, 52, which can be assembled to form a closed ring structure, the magnetic core rings 4, 4a, 4b, 5, 5a, 5b, and do not necessarily consist of only two parts. In addition, a conductor substrate 6 provided with at least two pairs of cutouts 61, 62, 63, 64 as yoke leg openings, specifically for each magnet core ring its own pair of cutouts, separate from other pairs. At least one of the two recesses of the first pair, namely the opening 61, has been made surrounded by the primary winding 1, as has the second recess 64 of the second pair with regard to the secondary winding 2. The other recess 62 of the first pair is connected via the coupling winding 3 to the Linked recess 63 of the adjacent pair of recesses.

The yoke core halves 41, 42 and 51, 52 are assembled to form the magnetic core rings 4, 5 in that the yoke legs are pushed through the associated cutouts in the conductor substrate 6 and the yoke core halves are closed to form a magnetic circuit each. As a result, the primary winding 1 is electromagnetically linked to the coupling winding 3 and, via this, to the secondary winding 2 .

It can be seen from the above that the transformer according to the invention is easy to manufacture. A potential separation can be achieved between the primary side and the secondary side, as is required, for example, for potentially explosive areas according to the EN 60079-11 standard. Only small spaces are required within the ring structure of the magnetic core rings, since a relatively high packing density of the windings on the primary side and the secondary side is possible without having to resort to the conventional winding of the yoke legs. Therefore, the economical production of the new Transformer possible, even with a miniaturized design of the transformer.

Claims (2)

1. A planar transformer, comprising:

   - a primary winding (1);

   - at least one secondary winding (2);

   - at least one coupling winding (3);

   - a first magnetic core ring (4) consisting of a ferromagnetic core and having yoke legs (44, 45), comprising two yoke core halves (41, 42) which surround a first ring core opening (43);

   - a second magnetic core ring (5) consisting of a ferromagnetic core and having yoke legs (54, 55), comprising two yoke core halves (51, 52) which surround a second ring core opening (53); and

   - a single plate-shaped conductor substrate (6) which nearly fills the first ring core opening (43) and the second ring core opening (53) and which has at least two pairs of cutouts (61, 62; 63, 64) which define openings for accommodating the yoke legs (44, 45; 54, 55) of the ferromagnetic cores;

   - wherein at least one (61) of the two cutouts of the first pair is surrounded by the primary winding (1) and this cutout (61) or the other cutout (62) of the first pair is looped by a first portion (34) of the coupling winding (3);

   - wherein furthermore at least one (64) of the two cutouts of the second pair is surrounded by the secondary winding (2) and this cutout (64) or the other cutout (63) is looped by a second portion (35) of the coupling winding (3);

   - wherein the primary winding (1), the secondary winding (2) and the coupling winding (3) are formed as integral portions of the single plate-shaped conductor substrate;

   - wherein, for potential separation purposes, at least a total isolation separation distance of a length L is kept between the primary winding (1) and the secondary winding (2);

   - wherein the primary winding (1) extends along a spiral path in two or more layer planes (11, 12, 13, 14) of the single plate-shaped conductor substrate (6);

   - wherein the at least one secondary winding (2) extends along a spiral path in two or more layer planes (21, 22, 23, 24) of the single plate-shaped conductor substrate (6);

   - wherein the coupling winding (3) extends in layer planes (31, 32) inside the plate-shaped conductor substrate (6), wherein layer planes (11, 14) of the primary winding (1) and layer planes (21, 24) of the secondary winding (2) extend on the surface or close to the surface of the conductor substrate (6), wherein the coupling winding (3) maintains a first partial insulation separation distance to adjacent layers of the primary winding (1) as well as to the first magnetic core ring (4), wherein the coupling winding (3) maintains a second partial insulation separation distance to adjacent layers of the secondary winding (2) as well as to the second magnetic core ring (5);
   and wherein the total isolation separation distance is made up of the sum of the first partial isolation separation distance and the second partial isolation separation distance, with the first partial isolation separation distance ranging from 1/3 to 1/2 of the total isolation separation distance, while the second partial isolation separation distance ranges from 2/3 to 1/2 of the total isolation separation distance, or vice versa.
2. A planar transformer, comprising:

   - a primary winding (1);

   - at least one secondary winding (2);

   - at least one coupling winding (3);

   - a first magnetic core ring (4) consisting of a ferromagnetic core and having yoke legs (44, 45), comprising two yoke core halves (41, 42) which surround a first ring core opening (43);

   - a second magnetic core ring (5) consisting of a ferromagnetic core and having yoke legs (54, 55), comprising two yoke core halves (51, 52) which surround a second ring core opening (53); and

   - a single plate-shaped conductor substrate (6) which nearly fills the first ring core opening (43) and the second ring core opening (53) and which has at least two pairs of cutouts (61, 62; 63, 64) which define openings for accommodating the yoke legs (44, 45; 54, 55) of the ferromagnetic cores;

   - wherein at least one (61) of the two cutouts of the first pair is surrounded by the primary winding (1) and this cutout (61) or the other cutout (62) of the first pair is looped by a first portion (34) of the coupling winding (3);

   - wherein furthermore at least one (64) of the two cutouts of the second pair is surrounded by the secondary winding (2) and this cutout (64) or the other cutout (63) is looped by a second portion (35) of the coupling winding (3);

   - wherein the primary winding (1), the secondary winding (2), and the coupling winding (3) are formed as integral portions of the single plate-shaped conductor substrate;

   - wherein, for potential separation purposes, at least a total isolation separation distance of a length L is kept between the primary winding (1) and the secondary winding (2);

   - wherein the primary winding (1) extends along a spiral path in two or more layer planes (12, 13) of the single plate-shaped conductor substrate (6);

   - wherein the at least one secondary winding (2) extends along a spiral path in two or more layer planes (22, 23) of the single plate-shaped conductor substrate (6);

   - wherein the coupling winding (3) extends in layer planes (31, 32) in the plate-shaped conductor substrate (6);

   wherein the layer planes (12, 13) of the primary winding (1) and the layer planes (22, 23) of the secondary winding (2) extend only inside the conductor substrate (6), wherein the coupling winding (3) extends on the surface or close to the surface of the conductor substrate (6); wherein the layers of the primary winding (1) maintain a first partial insulation separation distance to the coupling winding (3) as well as to the first magnetic core ring (4), wherein the layers of the secondary winding (2) maintain a second partial insulation separation distance to the coupling winding (3) as well as to the second magnetic core ring (5);

   and wherein the total isolation separation distance is made up of the sum of the first partial isolation separation distance and the second partial isolation separation distance, with the first partial isolation separation distance ranging from 1/3 to 1/2 of the total isolation separation distance, while the second partial isolation separation distance ranges from 2/3 to 1/2 of the total isolation separation distance, or vice versa.

Images