EP1544867A2 - Flexible flat cable with integrated output filter - Google Patents

Abstract

A flexible surface conductor comprises two electrically conductive layers (102) surrounded by an isolating sheath (106) and separated by an isolating dielectric layer (108). At least one layer has a recessed structure (109,111) so that many meandering elements (110). An independent claim is also included for a circuit part as above.

Description

The present invention relates to a flexible flat conductor with at least two electrically conductive layers of an electrically insulating sheath at least are partially surrounded, wherein the electrically conductive layers by at least a dielectric layer disposed between them are isolated from each other.

Furthermore, the invention relates to a power supply, such a flexible Has flat conductor.

Power supplies and chargers in the small power range are today due to Requirements for the wide input voltage range and lower losses than built a switching power supply. Widely used is the embodiment of a plug-in power supply 1, in which an electronic circuit for power conversion in a mounted directly on the power plug housing is arranged, as this is shown in FIG. A variety of such devices are used to charge portable devices, such as Mobile phones, PDAs, CD / DVD / MD / MP3 players and the like used. In particular, the size of the charger, its weight, plays a key role for portability as well as the simplicity of transport an important role. The connection to the Consumers (not shown in the figure) usually takes place via an output plug 2 and a two-pole output line 3, as a round or twin line is executed, as shown in Figure 1.

Furthermore, it is known in such network devices flat cable, which with a take-up device are used to insert. An example of such an arrangement is for example, in JP 2001/128350 and WO 01/21521 A1. Such arrangements allow a particularly space-saving and orderly storage of the cable during transport.

C1: 22 µF ... 470 µF

L: 1 µH ... 100 µH

C2: 10 pF ... 10 µF

For power conversion today usually a flyback converter, which is preferred due to the low circuit complexity in this power range. If the energy transmission takes place by means of a primary control, as shown in DE 100 18 229 A1, there is only one diode for rectification on the secondary side and an LC filter for filtering the output voltage. A circuit diagram of such a known output-side circuit is shown in Figure 2. While a ceramic capacitor is usually used for the capacitor C2 shown in FIG. 2, an electrolytic capacitor is usually selected due to the requirements for a low equivalent series resistance with a minimum cost for the capacitor C1. The components shown in Figure 2 typically have the following characteristics:

C1: 22 μF ... 470 μF

L: 1 μH ... 100 μH

C2: 10 pF ... 10 μF

As further shown in FIG. 3, the common mode noise is mostly suppressed downstream of a current-compensated inductor L3 'with final filter capacitor C3. However, the filter arrangements shown in Figures 2 and 3 require as conventional discrete components in the power supply considerable space and stand Therefore, contrary to further miniaturization of the power supply. In addition, you can via the output line also high - frequency interference coupled in the Consumers usually require an additional input filter and therefore Increase the size, weight and costs of the consumer.

Finally, it is known to filter structures as simple as possible inexpensive and space-saving to realize these in an integrated design with a flexible flat conductor manufacture. Japanese Laid-Open Patent Publication JP 06-139831 A is a flexible one Flat cable with integrated electronic components known therein. It will be various conductive structures surrounded by electrical insulation insulated from each other by a further dielectric layer, so that a capacitance is formed becomes. By means of a meander-shaped structuring of the conductor planes can after a subsequent folding process in which the individual meanders in the third dimension leporelloförmig superimposed, an inductance can be realized. The combination of capacitance and inductance provides an integrated filter here.

However, a disadvantage of this solution is that to those required for a filter structure Inductors form the flexible flat conductor in a defined manner must be folded several times, which in addition to increased effort in production also requires an increased space requirement. In addition, the required Folding of the flexible flat conductor according to JP 06-139831 A that only certain areas the flexible flat conductor can be used for the integrated filter structure, However, long stretches of the cable must remain unused.

It is therefore the object of the present invention to provide an improved flexible Flat conductor and a power supply with such a flat conductor indicate, at which the filtering can be improved, the space requirement can be reduced and at the same time the production costs can be reduced.

This object is achieved by a flexible lead with the features of the claim 1 and a power supply with the features of claim 10. advantageous Further developments of the present invention are the subject of several subclaims.

The solution according to the invention is based on the recognition that a particularly simple and space-saving realization of a filter structure achieved by an integrated arrangement in which at least one of the electrically conductive layers of the flexible Flat conductor is structured by recesses so that a plurality of meandering elements is formed, and wherein the meandering in a through the flat conductor defined level serially lined up to form the filter structure. Cost-intensive process steps, such as folding the flat conductor, are eliminated in this solution. Furthermore, the flexibility in the design, for example, one Output filter in a power supply significantly increased, because the entire length of the Line for the filter can be used. The flexibility of the cable remains on the obtained, for example, a winder without Problems are used. For this purpose, preferably a flexible ceramic dielectric embedded between the electrically conductive layers.

According to an advantageous development, the recesses take less than 50% the area of each meander element. This allows a sufficiently high inductance achieved at the same time only slightly increased DC resistance become. Also, the required capacity can be produced without problems.

In particular, when the recesses are formed by slots extending over about 50% of the width of the first conductive layer extends transversely to the longitudinal axis of the flat conductor and even have a width of less than 10% of their length, the increase remains of DC resistance in the order of less than 1.5%.

According to an advantageous embodiment of the present invention, the dielectric Layer divided by at least one recess into individual subregions. Thereby may advantageously different serial or parallel connected capacities will be realized.

Thus, for example, via a corresponding circuit of the meander structures in the first electrically conductive layer, the Π-filter are formed, as for example 2 are required.

More complex filter structures can be further realized by recesses both transverse to the direction of the longitudinal axis of the flexible flat conductor as well as in Direction of the longitudinal axis can be provided in the dielectric layer. With that you can implemented in a very cost effective manner a variety of required filter structures become.

If another of the electrically conductive layers is also structured by forming of meander structures, counter and common mode filters can be realized. This can be achieved in a very simple manner by the meander structures are either arranged in the same direction (whereby a push-pull filter can be realized can) or are arranged in opposite directions, creating a common mode filter.

The advantageous properties of the flexible flat conductor according to the invention come especially when used in a power supply with a primary-side connector and a secondary side connector between the secondary side Plug connection and the actual power supply is used as output line. One Such a power supply on the one hand has the advantage that the space required for the filter structures in the power supply can be drastically reduced, and on the other hand, too the system costs in the consumer, so the mobile terminal, can be lowered because an input filter can be avoided. Furthermore, in very space-saving and cost-effective manner, the functionality of the output filter to the needs of the power supply.

The power supply according to the invention can also be equipped with a take-up device be used to the flexible flat conductor, for example, for transport or At least partially unrolling the output cable.

Figur 1

eine perspektivische Darstellung eines Steckernetzteils nach dem Stand der Technik;

Figur 2

ein Schaltbild einer sekundärseitigen Filteranordnung;

Figur 3

eine weitere sekundärseitige Filterstruktur;

Figur 4

einen Querschnitt durch den erfindungsgemäßen flexiblen Flachleiter;

Figur 5

eine schematische Darstellung des flexiblen Flachleiters aus Figur 4 in der Draufsicht;

Figur 6

eine Draufsicht auf den erfindungsgemäßen flexiblen Flachleiter gemäß einer ersten Ausführungsform;

Figur 7

eine schematische Darstellung einer einzelnen Mäanderstruktur aus Figur 6;

Figur 8

eine schematische Darstellung eines flexiblen Flachleiters gemäß einer zweiten vorteilhaften Ausführungsform;

Figur 9

eine schematische Darstellung eines flexiblen Flachleiters gemäß einer dritten vorteilhaften Ausführungsform;

Figur 10

eine schematische Darstellung eines flexiblen Flachleiters gemäß einer vierten vorteilhaften Ausführungsform;

Figur 11

ein elektrisches Ersatzschaltbild der Anordnung nach Figur 10;

Figur 12

eine generische Stufe des Ersatzschaltbilds nach Figur 11;

Figur 13

eine Übertragungsfunktion für ein Filter mit 10, 20 oder 30 Stufen aus Figur 12;

Figur 14

ein elektrisches Ersatzschaltbild der Anordnung aus Figur 5;

Figur 15

ein elektrisches Ersatzschaltbild eines RCLC-Filters;

Figur 16

die Übertragungsfunktionen der Filterstrukturen aus den Figuren 14 und 15;

Figur 17

verschiedene Übertragungsfunktionen der Struktur aus Figur 15;

Figur 18

einen flexiblen Flachleiter gemäß einer weiteren Ausführungsform;

Figur 19

das elektrische Ersatzschaltbild der Struktur aus Figur 18;

Figur 20

eine weitere vorteilhafte Ausführungsform des erfindungsgemäßen flexiblen Flachleiters;

Figur 21

das Ersatzschaltbild der Anordnung aus Figur 20;

Figur 22

die perspektivische Darstellung eines Netzteils mit einem erfindungsgemäßen flexiblen Flachleiter.

With reference to the advantageous embodiments shown in the accompanying drawings, the invention will be explained in more detail below. Similar or corresponding details of the subject invention are provided with the same reference numerals. Show it:

FIG. 1

a perspective view of a plug-in power supply according to the prior art;

FIG. 2

a circuit diagram of a secondary-side filter assembly;

FIG. 3

another secondary-side filter structure;

FIG. 4

a cross section through the flexible flat conductor according to the invention;

FIG. 5

a schematic representation of the flexible flat conductor of Figure 4 in plan view;

FIG. 6

a plan view of the flexible flat conductor according to the invention according to a first embodiment;

FIG. 7

a schematic representation of a single meander structure of Figure 6;

FIG. 8

a schematic representation of a flexible flat conductor according to a second advantageous embodiment;

FIG. 9

a schematic representation of a flexible flat conductor according to a third advantageous embodiment;

FIG. 10

a schematic representation of a flexible flat conductor according to a fourth advantageous embodiment;

FIG. 11

an electrical equivalent circuit diagram of the arrangement of Figure 10;

FIG. 12

a generic stage of the equivalent circuit of Figure 11;

FIG. 13

a transfer function for a 10, 20 or 30-stage filter of Fig. 12;

FIG. 14

an electrical equivalent circuit diagram of the arrangement of Figure 5;

FIG. 15

an electrical equivalent circuit diagram of an RCLC filter;

FIG. 16

the transfer functions of the filter structures of Figures 14 and 15;

FIG. 17

various transfer functions of the structure of Fig. 15;

FIG. 18

a flexible flat conductor according to another embodiment;

FIG. 19

the electrical equivalent circuit diagram of the structure of Figure 18;

FIG. 20

a further advantageous embodiment of the flexible flat conductor according to the invention;

FIG. 21

the equivalent circuit of the arrangement of Figure 20;

FIG. 22

the perspective view of a power supply with a flexible flat conductor according to the invention.

FIG. 4 shows a cross section through a flexible flat conductor 100 according to the invention. The flexible flat conductor 100 has two electrically conductive layers 102 and 104, which are surrounded by an electrically insulating sheath 106. According to the invention, in order to integrate the function of a filter into the flexible flat conductor 100, the two electrically conductive layers 102, 104, which may be made of copper or aluminum, for example, are separated from one another by a dielectric 108. Initially, without further structuring of the metallic layers 102 and 104, a capacitance is formed between the conductors, which is calculated according to the following equation [1]. C = ε 0 ε r A / d

As a dielectric, a flexible ceramic dielectric with a dielectric constant of ε _r = 100 to 5000 is preferably embedded between the two layers of the metallic conductors 102, 104 and laminated together with two outer insulation films 106.

According to an advantageous embodiment, an output line according to the invention may have two meters total length and a cross-section of 2 x 0.25 mm ² . The geometric and electrical parameters can, for example, assume the following values: width of the copper foil 7 mm, thickness of the copper foil 35 μm, thickness of the dielectric layer 5 μm, relative dielectric constant ε _r = 1000 and thickness of the insulating foil 25 μm.

In order to achieve a uniform lamination of the outer insulating layers 106 results the resulting total width of the conduit 100 is 7.5mm in thickness of only 0.125 mm. These dimensions are particularly suitable for a space-saving Winding when using the flexible flat conductor 100 in a power supply, as shown in FIG 22 is shown. The space required compared to a conventional round cable (such as shown in Figure 1) is reduced by 22%.

With the above example values of the parameters, a resulting total capacity results between the two conductors 102 and 104 of approximately 25 μF. For switching power supplies with a switching frequency of, for example, 100 kHz, this value is sufficient to to obtain a sufficient screening of the output voltage. Furthermore, it has ceramic dielectric 108 over better high frequency characteristics, in particular via a lower series resistance (Low Equivalent Series Resistance, ESR) as a comparable electrolytic capacitor, so that despite the comparatively small Capacity reaches a sufficiently low voltage ripple at the end of the line becomes. In addition, results from the area distribution of capacity over the entire Surface of the pipe in connection with the very good heat transfer through the Copper electrodes a low self-heating of the flexible flat conductor 100 also at high currents through the dielectric.

According to the invention, the first of the two electrically conductive layers 102 is structured in such a way that that a meandering structure is formed, as shown in FIG. According to The first embodiment of the present invention remains the opposite one Copper foil 104 unstructured. This will make one parallel to the capacitor lying inductance whose value is approximately from the formula for a flat square coil with one turn calculated trained.

According to the invention, individual meandering elements 110 in the plane of the flexible Flat conductor serially strung together to produce the required inductance.

In the meandering structure shown in FIG. 6, which consists of a serial arrangement of meandering elements 110, each of which is relatively small in area Recesses 109, 111 are formed, the required inductance for an integrated filter manufactured in an elegant way only within the plane of the flexible flat conductor without needing, for example, a folding as shown in JP 06-139831. In this way, if necessary, the entire length of the flexible flat conductor be provided for the corresponding inductance with meandering elements 110. However, this is not absolutely necessary, but depends on what is needed Parameter from.

With reference to FIG. 7, now approximately the inductance achieved is to be calculated. In this case, it is assumed that the inductance of the individual meander element 110 shown in FIG. 7 is characterized by the basic geometry of a flat square coil with only one turn, which has a turn diameter a and a trace width w. The inductance L of such a meandering element 110 can then be calculated according to the following equation [2]:

The individual meander element 110 of FIG. 7 is characterized in that it passes through a comparatively small slot 109 in the electrically conductive material of the track 102 is formed. Between the individual meandering elements 110 are slots 111, which in the embodiment shown have the same dimensions as the Slits 109, arranged. For example, the slot may have a length of about 3.5 mm and a width of only 0.2 mm. With an edge length a of 7 mm Thus, the remaining trace width w 3.4 mm. Set these two values into the equation [2], so has a single meander 110 with the mentioned Dimensions an inductance of about 9 nH. The thickness t of the metallization was for this calculation is assumed to be 35 μm.

A juxtaposition of meandering elements 110 over the entire length of the flexible Flat conductor of two meters would thus lead to an inductance of 2.5 μH. Due to the special geometry of the meander elements, the DC resistance increases with only about 1.4% only insignificant.

FIG. 8 shows a further advantageous embodiment of the present invention. Interrupts namely, the dielectric 108 through a transverse to the longitudinal axis of the flexible Flat conductor arranged slot 112, resulting in two sections A1 and A2 (For clarity, structured layer 102 is shown in a raised position). As an equivalent circuit of the structure in FIG. 8, the Π-filter of FIG. 2 results.

By shifting the slot 112 along the longitudinal dimension of the flexible Flat conductor 100 at a constant inductance can be any division of the total capacity be achieved. The above dimensions are every millimeter in length for a capacity of about 10 nF. Due to manufacturing tolerances should the minimum dimension of one of the dielectric surfaces A1, A2 but not less than about 1 mm.

As a filter capacitor in mobile telecommunications equipment, such as mobile phones, a small capacity is particularly desirable at the cable end to prevent coupling of the carrier in the megahertz frequency range. This can be achieved by an additional slot 114 extending in the direction of the longitudinal axis of the flexible flat conductor 114 in the dielectric 108. This further embodiment is shown schematically in FIG. This results in two single capacitors with half capacity, symbolized by the areas A3 and A4, which are connected in series via the backside metallization 104. This results in a resulting capacity of approx. 2.5 nF. Assigning the cross section 114 asymmetrically, so that, for example, the area A3 is equal to 1/6 A4, it follows from equation [3] as the resulting capacity:

A minimal capacity within the today usual design rules arises, if one makes several transverse slots 114 so wide that only three dielectric surfaces of 1 mm x 1 mm. This results in the series connection a total capacity of about 100 pF.

A significant advantage of the present invention is that this Capacitance is located very close to the consumer and that thus interference frequencies, the be coupled via a conventional line, be suppressed much more effectively. This can optionally be dispensed with an additional filtering in the consumer and consumers can be made easier and cheaper.

About the choice of different longitudinal and horizontal stripes 112, 114 can be in the frame the maximum capacitances and inductors lying arbitrary filter combinations produce. Even multi-stage filters are possible.

FIG. 10 shows a flexible flat conductor 100 into which such a multi-stage filter is integrated. The associated electrical equivalent circuit diagram is shown in FIG.

To illustrate the many possibilities in the design of the filter characteristic For example, the filter of Figure 11 is decomposed into corresponding generic stages. Per level becomes a longitudinal inductance of 9 nH with an ohmic resistance of approx. 100 mΩ and assumed a lateral capacitance Ci of 85 nF. FIG. 12 schematically shows the generic level "i".

FIG. 13 shows the transfer functions for flexible flat conductors with 10, 20 and 30 stages shown. Reference numeral 116 denotes the curve for 10 juxtaposed generic stages of Figure 12, the curve 118, the transfer function for 20 Stages and the curve 120 the transfer function for 30 stages. As can be seen from FIG. 13, remains with an increase in the number of steps, the cutoff frequency constant, only the filter slope becomes larger. In a frequency range of less than 100 kHz is the Filter effect rather low.

When the flexible flat conductor does not have a meandering structure in the electrically conductive layer 102, 104, that is, when the inductance is negligible, only the capacitance is effective and there is a simple RC filter as shown in Figure 14. The whole achievable capacity over a length of 2 m is C1 = 25 μF.

In order to improve the high frequency characteristics, this arrangement can have another LC circuit can be followed by the flexible flat conductor only in the immediate Structured near the consumer. This results in the figure 15 as an equivalent circuit diagram illustrated RCLC filters. The transfer functions of the filter structures of FIG FIG. 14 and FIG. 15 are shown in FIG. 16 as a function of the frequency. there the curve 122 indicates the transfer function of the simple RC filter of FIG 14 and curve 124 illustrate the transfer function of the RCLC filter of FIG. 15. FIG can be seen on the curve 124, occurs at the RCLC filter resonance at about 5.5 MHz on. This is the resonant frequency of the LC circuit. From about 8 MHz, the attenuation better than the simple RC filter. By varying the values for the LC filter can affect the cutoff frequency (and therefore the high frequency attenuation characteristics) become.

FIG. 17 illustrates various transfer functions of the filter of FIG Variation of the values for the capacitance C2. Here, the value of the capacitance C2 in Range changed from 50 nF to 200 nF in 50 nF increments. The cutoff frequency drops increasing value of C2. In an analogous way, this can be achieved by a variation of the inductance L1 can be achieved. In Fig. 17, the curve 126 denotes the transfer function for C2 = 50 nF, the curve 128 the transfer function for C2 = 100 nF, the curve 130 corresponds to C2 = 150 nF and the curve 132 corresponds to a value of C2 = 200 nF.

A further increase in inductance can be obtained by adding both conductor surfaces 102, 104 are meandered on the top and bottom of the dielectric 108. So you can double the inductance with full utilization of the length again.

You get on the appropriate length a push-pull filter (also called differential mode Filter designated), as shown in Figure 18, in which with the above It has an effective capacitance of up to 22 μF and an effective inductance of up to 7 μH can be achieved. This interpretation arises when one considers the two Conductor surfaces congruent, that is, with the same direction arranged meandering elements 110 structured.

The equivalent circuit diagram corresponding to the arrangement of FIG. 18 is shown in FIG.

On the other hand, if the two conductor surfaces 102, 104 are oriented as shown in FIG. mirrored, so that the meandering elements 110 are each arranged in opposite directions, One obtains a common mode filter, its equivalent circuit diagram in FIG. 21 is shown. Thus, in the same direction disturbances by the opposing fields the two inductors on the top and bottom are extinguished.

In a particularly advantageous manner, the inventive flexible flat conductor for a Power supply, as shown in Figure 22, are used. This is the flexible flat conductor used as output line 203, which is the connection between the actual Power supply 201 and an output plug 202 manufactures. The output plug 202 can, as indicated in Figure 22, with a plurality of different consumers 205 (for example Mobile phones, PDAs, CD / DVD / MD / MP3 players and the like) be connected to provide them with electrical energy. The power supply 201 has in the embodiment shown a winding device 204, for example similarly as shown in Japanese Patent Laid-Open Publication JP 2001/128350 A, can be constructed. The cover of the power supply 201 is shown in dashed lines in FIG shown in order not to jeopardize the clarity.

With the flexible flat conductor according to the invention as the output line 203 can be within the given geometry of this output line the most diverse filter arrangements realize. This results in the power supply 201 next to the reduced Dimensions of the line arrangement, especially a space and cost reduction in the power supply. But also in a not shown here with the plug 202 To be connected terminal space and costs can be reduced because of a separate input filter can be dispensed with. Due to the planar structure of the flexible Flat conductor according to the present invention results in small tolerance deviations with high reproducibility and easier manufacturability. That is, the Filter structures can be formed with a high degree of reproduction.

Finally, the solution according to the invention allows the use of environmentally friendly Materials without additional plasticizers.

Claims (11)

Flexible flat conductor having at least two electrically conductive layers (102, 104) which are at least partially surrounded by an electrically insulating sheath (106),
wherein the electrically conductive layers (102, 104) are electrically insulated from one another by at least one dielectric layer (108) arranged between them,
wherein at least a first (102) of the electrically conductive layers is structured in at least one subregion by recesses (109, 111) such that a plurality of meandering elements (110) is formed,
wherein the meandering elements (110) are serially connected in a plane defined by the flat conductor (100) to form a filter structure. Flexible flat conductor according to claim 1, characterized in that the recesses (109, 111) each occupy less than 50% of the area of each meander element (110). Flexible flat conductor according to claim 1 or 2, characterized in that the recesses (109) are formed by slots which extend over approximately 50% of the dimension of the structured electrically conductive layer (102) transversely to the longitudinal axis of the flat conductor (100) and a width less than about 10% of their length. Flexible flat conductor according to one of claims 1 to 3, characterized in that the dielectric layer (108) is formed by a flexible ceramic dielectric. Flexible flat conductor according to one of claims 1 to 4, characterized in that the dielectric layer (108) is subdivided by at least one recess (112, 114) into individual subregions (A1, A2, A3). Flexible flat conductor according to claim 5, characterized in that two partial regions (A1, A2) of the dielectric layer (108) are connected to the electrically conductive layers (102, 104) such that a Π-filter is formed. Flexible flat conductor according to claim 5 or 6, characterized in that the individual partial areas (A1, A2, A3) by at least one transverse to the direction of the longitudinal axis of the flexible flat conductor extending recess (112) and at least one extending in the direction of the longitudinal axis of the flexible flat conductor recess (114) are generated. Flexible flat conductor according to one of claims 1 to 7, characterized in that the first and a second electrically conductive layer (102, 104) are structured so that meandering meandering elements (110) are formed in at least a portion of the flexible flat conductor (100) , which are interconnected to a push-pull filter. Flexible flat conductor according to one of claims 1 to 8, characterized in that the first and a second electrically conductive layer (102, 104) are structured so that in at least a portion of the flexible flat conductor (100) arranged in opposite directions meandering elements (110) are formed , which are interconnected to a common mode filter. Power supply unit with a primary-side plug connection (200) and a secondary-side plug connection (202), characterized in that the secondary-side plug connection (202) is connected to the power supply unit (201) via a flexible flat conductor (203) according to at least one of Claims 1 to 9. Power supply unit according to claim 10, characterized in that the flexible flat conductor (203) by means of a winding device (204) can be rolled up.

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