DE102008039235B4 - Headrest for a vehicle seat - Google Patents

Abstract

Headrest (10) for a vehicle seat, with a detection device with which a position of a head (17) of a passenger located on the vehicle seat relative to the headrest can be detected, characterized in that an electrode arrangement (21) is arranged on the headrest, which to determine the relative distance (d) of the head from the headrest in the longitudinal direction (x) of the vehicle, several measuring areas (45a, 45b, 45c) lying one above the other in the vertical direction are formed.

Description

The invention initially relates to a headrest for a vehicle seat according to the preamble of claim 1.

Such a headrest of the prior art is known from the German patent application DE 10 2006 023 102 A1 the applicant known.

The known headrest has a detection device with an electrode arrangement which comprises at least three electrodes. The electrodes each extend over a substantial portion of the width of the headrest and are spaced apart in the vertical direction.

The electrode arrangement serves to carry out a capacitive measurement. For this purpose, an alternating electrical voltage of a predetermined frequency and a predetermined amplitude is applied between each two electrodes. In this way, an alternating electric field is generated. The electrode arrangement is connected to a control unit, which is equipped with measuring electronics. The measuring electronics makes a measurement, which is accompanied by a change of the alternating electric fields. The passenger's head influences the alternating electric field. This is due in particular to the fact that, in the event that the head of a passenger is in the alternating electric field, this is physically a medium with a _relative permittivity ε _r , which differs from the dielectric constant ε _r air of the air.

With regard to the possible type of embodiment of the measuring circuit, reference is made, by way of example, to the applicant's prepublished patent application mentioned at the beginning.

Performing such capacitive measurements to determine the relative head position of the passenger relative to the headrest - for the purpose of achieving optimum alignment of the headrest in the vertical and / or horizontal position - requires the most accurate possible capacitance measurement. On the one hand the largest possible range of the measuring apparatus is desired, for example, to determine whether the head of the passenger 10 or more inches away from the front of the headrest. At the same time, however, the relevant field strengths of the electric field are to be kept as low as possible in order to comply with the EMC limit values, in order to prevent adverse health effects, but also to exclude interactions with other electronic components in the vehicle as far as possible.

The headrest of the prior art allows a determination of the relative position of the head of the passenger to the headrest in the vertical direction. It is also desirable to determine the relative head position relative to the headrest in the vehicle longitudinal direction. Trailing the headrest in the vehicle's longitudinal direction allows for optimization of the relative headrest position and a reduction in the risk of injury in the event of an accident.

Particular problems are the design of the measuring circuit, the electrode geometry and the type of measurement. The electrodes are typically enveloped by a covering material or by a leather layer or the like and possibly also by a cushioning layer. This creates problems in sizing the required field strengths. In addition, the possibility of arranging electrodes on a headrest is anyway very limited due to the given size and geometry of the headrest.

Furthermore, it should be noted that the comfort that is to provide a headrest for a passenger, may not be reduced by an electrode assembly. In other words, a use of z. As hard-trained electrodes, which would feel the passenger in leaning his head to the front of the headrest, unacceptable.

Finally, in the measurement of the capacities or in the calculation of the electric fields, stray capacitance plays an important role. In addition to the basic problem, according to which the motor vehicle, even in the manner of a Faraday cage, brings with it special electromagnetic conditions, other electronic assemblies in the vehicle with their electromagnetic signals also influence the capacitive spatial conditions and constitute unwanted sources of interference.

Next, the electrode geometry is to be dimensioned such that at completely different temperature and humidity conditions as well as different textures of the head or shoulder area of the person, z. As well as in the event that the passenger has wet hair, has no hair or wearing a headgear, a high-quality statement about the relative position of the head based on the position of the headrest over the entire life of the vehicle can be made.

Finally, the measurement should be performed within a shortest possible time so as not to affect the comfort of the passenger. Furthermore, the measurement should allow a high susceptibility to interference.

The object of the invention is to further develop the headrest shown in the applicant's patent application described above such that an improved detection of the head position of a passenger relative to the headrest is possible.

The invention solves this problem initially with the features of claim 1, in particular with those of the characterizing part and is accordingly characterized in that an electrode assembly is arranged on the headrest, which for determining the relative distance of the head of the headrest in the vehicle longitudinal direction in a plurality of layers in the vertical direction forms superimposed measuring ranges.

Essentially, the principle of the invention consists in providing an electrode arrangement which, in contrast to the electrode arrangement of the headrest of the prior art, forms layered superimposed measurement areas. In the electrode arrangement of the prior art, club-shaped measuring areas were formed. However, these were not hit in a layered, superimposed arrangement.

Also from the DE 10 2005 010 594 A1 Only a headrest and a detection device is known in which a circumferential sensor array is formed approximately club-shaped in section. For the detection of a head in the vehicle longitudinal direction there is also provided only a sensor with a measuring range.

Due to the inventive layered design of the measuring ranges, ie a substantially flat, d. H. along a plane aligned extension of the measuring ranges, a measurement of the relative head position in the vehicle longitudinal direction can take place. At the same time, the layered training grants a high range of measurement. Due to the layered overlapping arrangement, different, vertically spaced apart sections of the passenger's head, at the same time or in short succession, alternating fields can be exposed and measured at the same time at a predetermined, vertical position of the headrest. Thus, a particularly rapid determination of the actual relative position of the head relative to the headrest can be made. For example, this can be done by a comparative analysis of the obtained measured values with stored data on contours of body sections of passengers, which is explained below.

The geometrical design of the electrodes for achieving a plurality of measurement areas arranged one above the other in a layer-like manner can be carried out in various suitable ways. For example, a plurality of pairs of electrodes may be provided, each comprising an outer, annular electrode and a centrally located counter electrode. However, other electrode geometries are possible as well.

The headrest according to the invention also allows a measurement of the relative head position with respect to the vehicle longitudinal direction, wherein from the fact that measurements take place in the vehicle longitudinal direction along different vertical sections, at the same time a statement about the vertical relative head position can be made. Thus, by carrying out a single measurement in, for example, three measuring ranges, a statement can be made both about the relative position of the headrest in the vehicle longitudinal direction and in the vertical direction.

According to an advantageous embodiment of the invention, the relative distance of the head from the headrest in the vehicle longitudinal direction and / or in the vertical direction for the individual measuring ranges can be determined individually. In that regard, measurements for all layered superimposed measuring ranges can be performed simultaneously or sequentially.

It is particularly advantageous that in this embodiment of the invention, only a single measurement, performed in all measuring ranges, is required to obtain information about the relative positions in the vehicle longitudinal direction as well as in the vertical direction.

According to an advantageous embodiment of the invention, the electrode arrangement comprises at least three vertically spaced pairs of electrodes. This can be achieved in a particularly simple, constructive way, a layered, superimposed formation of multiple measuring ranges.

Advantageously, the measuring range of the respective measuring ranges in the vehicle longitudinal direction to the front is at least 30 mm. According to further advantageous embodiments of the invention, greater ranges are provided. The measuring range of the individual measuring ranges can be up to 200 mm. The individual measuring ranges can also have different measuring ranges.

The layered measurement areas are aligned along parallel planes. Furthermore, they are preferably designed to be at least partially overlapping in the vertical direction. This means that in the vertical direction, a measurement can be carried out substantially gap-free.

The invention further solves this problem with the features of claim 7, and is accordingly characterized in that in a memory of the detection device comparison values are arranged, which represent a profile of the contour of body parts of a human, and for the purpose of comparison with the measured values that can be obtained when performing a measurement.

The principle of the invention will be explained as follows: The detection device has a memory or it is associated with a memory. This may be, for example, an electronic, electrical, optical, electromagnetic or other volatile or non-volatile memory. In this memory comparison values are written. These comparison values have been inscribed by the manufacturer and represent a contour of body sections of a human body. The relevant contour profile comprises, in particular, the course of the rear side of the human head, and optionally also the contour of the back of the neck region of a human and of the upper shoulder region. The comparison values written in the memory represent typical trajectories that characterize a typical passenger. For example, standard values can be used for this purpose.

The contour curves of the body sections can be stored, for example, continuously or in the form of individual selected points.

The detection device may perform a calibration measurement during operation, for example when a passenger opens or unlocks the vehicle door. The calibration measurement thus takes place in the absence of a passenger. Once the passenger is seated on the vehicle seat, which can be automatically determined, for example, by actuating the engine ignition, a measurement of the relative head position of the passenger relative to the headrest can be made. The measured values obtained on the basis of this measurement can now be compared with the comparison values. For this purpose, the comparison values can be used.

By making the comparison, the measured values obtained by a measurement on the real passenger can be compared with the comparison values stored in the memory. As a result of making the comparison, it can be determined optimally which measured values correspond to which body sections of the passenger. Thus, the relative head position can be determined optimized and optimized tracking of the headrest can be achieved.

Advantageously, the implementation of the comparison and the tracking of the headrest done fully automatically.

The invention further relates to a headrest according to the preamble of claim 8.

This invention is equally based on the object to improve the previously known headrest of the Applicant and further develop the headrest in particular such that a higher level of safety of the passenger can be achieved.

The invention achieves this object with the features of claim 8, in particular with those of the license plate part, and is accordingly characterized in that the detection device performs a calibration measurement, controlled by a first event, before the passenger has taken place, and that the detection device below controlled by a second event, or timed, makes a second measurement to determine the position of the head relative to the headrest.

Essentially, the principle of the invention is that the detection device performs a calibration measurement each time before the journey starts and before a passenger takes a seat. The calibration measurement is thus carried out in the absence of a passenger.

The calibration measurement is controlled by a first event. This event may be, for example, the detection of a door opening or door unlocking of the vehicle. Alternatively, the event may also be the determination of an approach of the passenger to the vehicle or the like.

The detection device subsequently takes a measurement for determining the relative head position after the passenger has taken a seat. This measurement is event-controlled or time-controlled. As a suitable second event for initiating the performance of a relative head position measurement, for example, a signal provided by a seat occupancy detection sensor may be used. Alternatively, a determination that a passenger has fastened his seatbelt, or a determination of a successful engine ignition, engagement of a gear, the achievement of a minimum speed, or the like, may be used as a second event.

Alternatively, a timed measurement may be performed so that each time a certain period of time passes after the calibration measurement has been made, a measurement of the relative head position are performed. The suitable period of time may be, for example, 30 or 60 seconds.

The measurement to be carried out is in knowledge of the measured values obtained during the calibration measurement of the most exact determination of a relative head position. The calibration measurement is carried out at a certain temperature and humidity and under certain electrical, electronic and electromagnetic conditions in the vehicle. Performing the relative head position measurement takes place - shortly thereafter - under the same conditions. In this way, an optimized consideration of the given real conditions can take place.

Advantageously, a measurement can be repeated regularly during a journey. For example, a measurement every 30 minutes or every 60 minutes or the like, if necessary, also regularly in short intervals, take place. Of course, a repetition of the measurement makes sense only if the detection device determines by receiving a corresponding signal that the vehicle is still moving or the passenger is still in the seat.

The invention further relates to a headrest according to the preamble of claim 11.

Based on the above-described prior art headrest of the Applicant, the object of the invention is to improve the known headrest and in particular to further develop such that a higher level of safety of the vehicle occupants can be achieved.

The invention solves this problem with the features of claim 11, in particular with those of the characterizing part, and is accordingly characterized in that the detection device and the distance of the head relative to the headrest in the vehicle longitudinal direction is detectable, and that the detection device is a measurement of the distance of the head from the headrest in the vertical direction at the same time as measuring the distance of the head from the headrest in the vehicle longitudinal direction.

The principle of the invention essentially consists in that, in addition to the measurement of the relative head position in the vertical direction, the relative head position in the vehicle longitudinal direction is measured. It is further provided that a measurement of the relative position in the vehicle longitudinal direction takes place simultaneously with the measurement of the relative position in the vertical direction. By performing a simultaneous measurement, the time required to detect and, if necessary, calculate the relative head position and track the headrest position can be minimized. Thus, the safety of the passenger can be increased. Also, the fastest possible optimization of the relative headrest position is possible in this way.

As a simultaneous measurement within the meaning of the invention, in particular a measurement is considered in which all measured values are obtained from a specific, in particular also arbitrary, relative headrest position, without a displacement of the headrest being necessary during the measurement.

In the prior art, it has sometimes been necessary for the headrest to fully travel along its possible vertical displacement path, and to stop at various points to perform multiple measurements.

The DE 10 2005 010 594 A1 discloses in this sense a headrest, which must first be moved vertically to a highest position before a measurement. A first proximity switch can detect the region of maximum curvature of the back of the head of a vehicle occupant during a subsequent shutdown of the headrest and stop the headrest at shutdown at this moment. The headrest is also associated with a second sensor element, which can make or trigger a tilt adjustment or translational adjustment in the direction away from the head or on the head. However, this can not be done simultaneously with the measurement of the first sensor element, since the second sensor element would adversely affect the measurement of the first sensor element by a triggered displacement of the headrest. A simultaneous measurement by the two sensor elements is certainly not disclosed in the cited document.

According to the invention, the measurement can be carried out from a single relative headrest position and all required measured values can be obtained.

As a simultaneous measurement in the sense of the invention, it is also considered that different electrode pairs are addressed for the purpose of testing different measuring ranges in a short chronological sequence with the headrest fixed. Thus, for example, in the case of a headrest which has an electrode arrangement which provides a plurality of layer-like measuring areas which lie one above the other in the vertical direction, each of the three measuring areas can be interrogated in a short time sequence. Such a measurement is considered as a simultaneous measurement in the sense of the invention.

Numerous attempts by the Applicant have revealed that the described features, which are expressed in the various independent claims, permit a particularly optimized measurement, a particularly high susceptibility to interference, a particularly high range and a particularly high-quality statement about the relative head position , Particularly advantageous is the use of a closed, ring-shaped electrode, which allows a particularly high number or density of electric field lines. Since the number or density of the field lines is a measure of the strength of the electric field, can be achieved with the selected geometry of the electrodes obviously very far reaching electric fields that allow a long range of measurement. At the same time, however, the electric fields can be very strongly focused, so that the EMC limit values can be maintained overall.

The particular electrode geometry is already used advantageously when only two pairs of electrodes, each consisting of a first, outer, annular and a second inner electrode is arranged on the headrest. Equally, however, the invention can also be advantageously used if three or more electrode pairs, each composed of an inner and an outer electrode, are provided.

In addition to a particularly long range, the special electrode geometry in test series has also proven to be particularly susceptible to stray capacitance. In particular, the electrode geometry according to the invention using ring-shaped external and centrally arranged electrodes proves more suitable than other electrode geometries. This geometry appears to be particularly advantageous for the specific application on a headrest on a vehicle seat.

An annular electrode is understood to be any electrode which has an inner, essentially central recess, a second electrode being arranged in the recess, electrically insulated from the outer annular electrode. The annular electrode is substantially planar. It may be circular, substantially rectangular, or any other contour. Also included are those electrodes in which an irregular edge contour, for example projecting corner regions, are provided.

Also conceivable are electrode geometries in which a planar large electrode has two or more recesses, wherein in each recess a smaller, inner electrode is arranged, which is surrounded by the outer electrode.

Further, it is also conceivable that an outer annular electrode has a recess in which two or more inner electrodes are arranged, which are jointly surrounded by the outer electrode.

According to an advantageous embodiment of the invention, the first electrode extends along a plane which is aligned substantially parallel to the vehicle longitudinal direction front side of the headrest. The front in the vehicle longitudinal direction of the headrest is the front, d. H. the side of the headrest facing the passenger's head. The headrest usually has an aligned along a plane, possibly also slightly curved front. To this level, the first electrode extends substantially parallel.

According to a further advantageous embodiment, the inner, second electrode may be formed by a point-shaped electrode. Alternatively, the inner electrode may be formed by a filamentary electrode. For the purposes of the present patent application, the term "point-shaped electrode" denotes any electrode which has a significantly smaller area than the first electrode. In particular, an embodiment in which the first electrode is annular and the inner electrode is punctiform, proved in test series to be advantageous.

The thread-like electrode is any inner electrode that has a substantially line-like geometry. Such a geometry is particularly advantageous if in the first, annular electrode only a narrow slot is arranged, which serves to receive the inner electrode.

It is particularly advantageous to use a pair of electrodes whose first electrode has a substantially larger area than the second electrode.

After carrying out numerous test series, the invention has recognized that in order to achieve a high range, a high measuring accuracy and a high susceptibility to interference in the specific application of a headrest for a vehicle seat, the most extreme possible ratio of the surfaces of two electrodes is advantageous. When using such an electrode geometry evidently form in a headrest in a vehicle seat, due to the special nature of the flock of electric field lines, alternating fields, for provide a reliable, trouble-free and far-reaching measurement.

Advantageously, the area of the first electrode is made larger by a multiple than the area of the second electrode. This comprises in particular pairs of electrodes in which the surface of the first electrode is formed at least five times, preferably at least ten times, more preferably at least twenty times, more preferably at least one hundred times as large as the area of the second electrode.

The front surface of the respective electrode in the vehicle longitudinal direction is formed by that surface of the electrode which faces the head of a passenger seated on the vehicle seat. The size of the electrode is measured along a plane which is formed transversely to the vehicle longitudinal axis.

The closer geometric configuration of the first and the second electrode according to this invention is initially arbitrary. Advantageously, however, the first electrode is formed as an annular electrode surrounding the second electrode. Alternatively, however, the second electrode may also be formed as a point or filament electrode and be arranged, for example, next to a first electrode formed over a large area. Finally, embodiments are contemplated in which a plurality of pairs of electrodes are provided, each pair having a first, large-area electrode and a second, small-area electrode.

According to an advantageous embodiment of the invention, the first surface is at least three times as large as the second surface.

According to a further advantageous embodiment of the invention, the first surface is at least six times as large as the second surface. Further advantageously, the first surface is at least ten times as large, more advantageously at least twenty times as large, more advantageously at least one hundred times as large as the second surface.

As the first and second surface in the sense of the present patent application, in each case the surface of the electrode is understood, which is arranged in the vehicle longitudinal direction at the very front of the electrode. In the event that according to an advantageous embodiment of the invention, both electrodes are formed as a surface electrode, and these surfaces are aligned along a plane transverse to the direction of travel of the vehicle, correspond to the first and second surfaces in the sense of this patent application the electrode surfaces.

However, in the event that the electrodes are not formed in a planar manner but - which would be unfavorable - as three-dimensional bodies, the surfaces which are furthest forward in the direction of travel are considered as surfaces in the sense of this patent application, that is those sides of the electrodes which correspond to the Head of the passenger are facing.

According to an advantageous embodiment of the invention, the two surfaces are arranged substantially along a common plane. This may preferably be a plane arranged transversely to the vehicle longitudinal direction.

According to a further advantageous embodiment of the invention, at least two electrodes are provided, each front of which arranged in the direction of travel surfaces in the sum represent a larger area than half of the front surface of the headrest. As in the vehicle longitudinal direction front surface of the headrest, the viewing surface of the headrest is referred to, so the surface of the headrest, which faces the head of the passenger. Assuming a substantially cuboidal headrest is thus referred to as the front surface of the headrest, the rectangular area that opposes the seated passenger when he looks at the headrest.

The Applicant recognizes after carrying out numerous test series that it is important to achieve a high range, to achieve a high measurement accuracy and to increase susceptibility to interference in particular to make the total area provided by the multiple electrodes as large as possible. It has been found to be advantageous if the entire electrode surface is at least half the viewing surface of the headrest.

It is irrelevant for the invention first, whether the electrode arrangement has only two electrodes, or more than two electrodes, for. B. six, seven, eight or ten electrodes.

Further advantageously, the sum of the surfaces is more than 60%, more advantageously more than 70%, more advantageously more than 80% and more advantageously more than 90% of the front surface of the headrest in the vehicle longitudinal direction. The requirements for measurement accuracy and susceptibility to failure of the device are - so the result of the test series - increasingly satisfied with increasing electrode surface.

According to a further advantageous embodiment of the invention, an electrode assembly having a plurality of electrodes is arranged on the headrest, which is used to determine the relative distance of the Head are switched from the headrest in the vehicle longitudinal direction in a first way and are connected to determine the relative distance of the head of the headrest in the vertical direction to a second, different from the first kind.

The principle of this circuit change is that in a headrest for measuring a distance of the head of the passenger relative to the headrest in the vertical direction and in the vehicle longitudinal direction take different measurements. The electrode arrangement, which has a plurality of electrodes and which is arranged on the headrest, can be switched in two ways for this purpose. In a first measurement, the electrodes are switched such that a determination of the relative distance in the vertical direction can be made. For this purpose, for. B. several pairs and vertically spaced from each other arranged electrodes each acted upon by AC voltage.

For measuring a distance of the headrest to the head in the vehicle longitudinal direction, however, another type of circuit is selected. Here are the electrodes z. B. switched such that a plurality of large-area electrodes are at the same potential and preferably only a smaller electrode is at a counter potential. By switching a plurality of electrodes to a same potential during the measurement, the electrode area available during a measurement can be maximized. As a result, a range maximization, but also a particularly high Störunanfälligkeit is achieved.

The detection device, in particular a control unit of the detection device, can automatically perform the switching between the two types of circuit. In particular, automatically within a control unit, for. B. by a microprocessor, a switch folded, or made a slightly different control of the electrodes.

The type of measurement just described, in which two different switching states of the electrode arrangements are used, is considered to be a simultaneous measurement within the meaning of claim 11 of the present patent application. The reason for this is that the two measurements can be carried out with the headrest fixed, without the headrest having to be moved.

The headrest is advantageously height adjustable and adjustable in the vehicle longitudinal direction. Thus, an optimal headrest position based on the detected position of the head of the passenger can be achieved both by a height adjustment and by an adjustment of the headrest in or against the vehicle longitudinal direction.

Further advantageously, the headrest is adjustable by means of a motor drive. The motor drive can adjust the headrest advantageously in the vertical direction and / or in the vehicle longitudinal direction. For this purpose, any suitable motor drive can be used. In this case, both drives into consideration, in which an adjustment of the headrest in the longitudinal direction is independent of an adjustment of the headrest in the vertical direction, or alternatively such drives in which superimposed movements, such as pivotal displacements of the headrest, take place, the movement direction component in the vertical direction as well have a movement direction component in the vehicle longitudinal direction.

Further advantageously, the electrode assembly is disposed near the front of the headrest. The electrode arrangement is typically of a cushion layer and / or of a reference, for. B. of a textile lamination or possibly also of a leather lamination, covered. With respect to the placement of the electrode assembly in the headrest and the positioning relative to the padding can be applied to the German patent application of the applicant DE 10 2006 023 102 A1 The disclosure of which is hereby included in the content of the present patent application, also for the purpose of reference to one or more features.

The inventions will now be explained by way of example with reference to the description of the embodiments in the drawings. For the sake of clarity, the same or comparable parts or elements, even if they can be assigned to different exemplary embodiments, are designated by the same reference numerals for the sake of clarity, partially with the addition of small letters.

In the drawings show:

1 2 shows a schematic side view of the head and shoulder region of a vehicle passenger and a head region of a motor vehicle seat back with a headrest according to the invention mounted thereon,

1a in a schematic sectional view, approximately along an in 1 with 1a-1a designated cutting line, the arrangement of 1 .

2 a headrest according to the invention in a schematic, fragmented front view, approximately along a line of sight along the View arrow II in 1 omitting a cover of the headrest,

3a in a detailed representation of the contour or silhouette of the passenger according to 1 .

3b the course of the contour of the rear of the head, neck and upper shoulder of the passenger in dashed line representation,

3c the representation of 3b with additionally exemplified measured values resulting from a measurement of the detection device, and

4 in a schematic, enlarged view of the control device 41 of the 1 with two schematically represented memories or registers in which contour profiles and measured values are written.

The in their entirety in the figures with 10 designated headrest is about at least one support rod 11 , preferably via a pair of support bars 11a . 11b , on the head 12 a vehicle seat back 13 appropriate. The headrest 10 is with respect to the vertical direction z, ie in height, displaced. Similarly, the headrest is advantageous in the direction of travel x, ie in the vehicle longitudinal direction, displaced in a suitable manner.

For this purpose, z. B. in the backrest 13 a schematically indicated drive 44 , For example, an electric motor, be arranged. In this context, reference is also made to the German patent application DE 10 2006 023 102 A1 the Applicant, the possible Verstellarten mentioned.

1 shows a passenger 14 who has sat down on the seat, which is not fully illustrated. This may be, for example, the driver of the vehicle, but also the passenger or a passenger in the rear seat area. Typically, the passenger leans with his back 15 at the vehicle front longitudinal direction x front side 16 the backrest 13 at.

The head 17 of the passenger is a distance d in the vehicle longitudinal direction x from the front side 18 the headrest 10 spaced. The top 19 Of the head 17 the passenger is substantially flush with the top 20 the headrest 10 ,

At the headrest is - as in 1 schematically indicated - an electrode assembly 21 arranged near the front 18 the headrest is positioned. One recognizes in 1 , only schematically indicated, a cushion support 22 that of a cushion layer 23 , for example formed from a foam, is surrounded. The headrest 10 has on its outside beyond a cover or a laminating layer 24 on, which may be formed for example of a textile material or leather or of multilayer materials.

The electrode arrangement 21 is located, for example, between the outer layer 24 and the upholstery 23 , optionally between the pad 23 and a cushion carrier 22 ,

As described in the applicant's patent application cited above, the electrode arrangement is 21 about in 1 only indicated electrical lines 42a . 42b . 42c with a control unit 41 connected, which has an electronic measuring circuit or is connected to a measuring circuit. The control unit 41 can be over an illustrated line 43 with the drive motor 44 be connected. However, this representation is only to be understood as an example. Similarly, the control unit 41 also in the area of the backrest 13 be arranged, with the supply lines 42a . 42b and 42c or the supply line 43 through the hollow support rods 11a . 11b the headrest can run.

The control unit 41 and / or one of the control unit associated, not shown measuring electronics or measuring circuit, the electrodes of the electrode assembly 21 apply alternating voltage, so that the space in the direction of travel x in front of the headrest 10 is exposed to an alternating field. This alternating field is used to detect the presence of the head 17 of the passenger 14 and determining its spatial position relative to the headrest 10 , In this case, in particular, the detection of the distance d and the detection of a distance in the vertical direction z between the upper side plays 19 Of the head 17 and the top 20 the headrest 10 a special role.

The goal is, in particular starting from different initial starting positions of the headrest 10 , ie different vertical positions of the headrest at the beginning of a measurement, for different sized passengers optimal alignment of the headrest relative to the head 17 of the passenger 14 to achieve.

For this, the measurement can be performed, and the headrest 10 in the knowledge of the obtained measurement results optimally tracked and relative to the head 17 be positioned.

For this purpose, a calibration measurement is first performed at a time at which the passenger 14 not yet on the seat. Such a calibration measurement is event-controlled. For example, the event " Door opening "be detected by the electronics of the vehicle and a corresponding signal to the control unit 41 , which may be connected to the central vehicle electronics, transmitted. The control unit then performs the calibration measurement, which measures the readings in the absence of a head 17 a passenger 14 supplies.

Subsequently, it can be determined in any suitable way that a passenger 14 Took a seat. Now, the actual measurement can be performed, which is to determine the relative position of the head of the passenger. The second measurement preferably takes place in an event-controlled manner, for example as a result of a determination of an actuation of the engine ignition of the vehicle. Other events can be used for this purpose. Finally, a timing could be done so that at a certain time after performing a calibration measurement, for example, 30 seconds thereafter, a head position measurement is performed.

The present invention is particularly concerned with the formation of the electrode assembly 21 and the design of the measurement. Details of the circuit electronics will not be further described in the present case. Reference is made to the above-mentioned patent application of the applicant.

An embodiment of an electrode arrangement according to the invention 21 a headrest 10 turns out 2 , The headrest 10 is shown there with a conventional design. It has a substantially trapezoidal front 18 with rounded corners on. The outer contour of the headrest 10 is denoted by K. However, the invention is not limited to headrests 10 with a contour K, as in the 2 shown, limited. Also any other contours of the headrest 10 are equally conceivable.

2 shows the headrest 10 under a viewing direction in the vehicle longitudinal direction x to the rear, ie contrary to the direction of travel x. The viewer thus enters the front so far 18 the headrest against.

The electrode arrangement 21 has six electrodes 25a . 25b . 25c . 25d . 25e . 25f on. The electrodes are in 2 shown in solid lines. 2 However, this is only to be understood schematically. In fact, the viewer would get the headrest 10 of the 1 the electrode assembly 21 of the 2 so do not represent, since the fabric or the laminating 24 usually not transparent. A view of the electrode assembly 21 according to 2 thus does not reveal itself to the viewer until the laminating layer 24 would be removed.

The six electrodes 25a . 25b . 25c . 25d . 25e and 25f are grouped into three pairs of electrodes. The electrodes 25a and 25b form a first pair of electrodes, the electrodes 25c and 25d together form a second pair of electrodes, and the electrodes 25e and 25f form a third pair of electrodes.

Each pair of electrodes includes a first large electrode 25a . 25c . 25e and a second smaller, inner electrode 25b . 25d . 25f , The respective inner electrode is in the embodiment of 2 designed as a thread electrode. This means that the electrodes 25b . 25d and 25f are formed substantially linearly elongated.

The three outer electrodes 25a . 25c and 25e are formed as ring electrodes. These are substantially flat electrodes, each having a central recess 26a . 26b . 26c exhibit. The recesses are formed substantially slit-like and provide an accommodation space for the respective filament electrode 25b . 25d and 25f ready.

It should be noted that both the length S and the width B of the respective slot (exemplified by the recess 26b in 2 ) is suitably selectable and in particular the dimensions of the respective inner thread electrodes 25b . 25d and 25f can correspond. It is also noted that the 2 the electrode assembly 21 only schematically represents. The slots 26a . 26b . 26c are in 2 shown with an exaggerated size shown width B and length S.

The slots 26a . 26b . 26c essentially serve to each of the inner electrode 25b . 25d . 25f in electrical isolation to the respective outer ring electrode 25a . 25c . 25e to arrange.

Each of the electrodes 25a . 25b . 25c . 25d . 25e and 25f is over in 2 not shown supply lines 42a . 42b . 42c (see. 1 ) with the control unit 41 and / or connected to a measuring electronics, not shown. In each case between the electrodes of a pair of electrodes, for. B. between the electrodes 25a and 25b , an AC voltage can be applied. When an alternating voltage is applied, a flock of lines of the electric field is produced. The electric field lines are substantially perpendicular to the respective portion of the surface of the electrode. In the area of the slots 26a . 26b and 26c This results in a very high density of E-field lines. Thus, the E-field can be focused and a particularly large measuring range can be achieved. At the same time the susceptibility is reduced.

The electrode arrangement 21 with a geometry according to 2 has been shown to be particularly advantageous. It should be emphasized that the large area formed electrodes 25a . 25c and 25e together almost the entire surface of the front 18 the headrest 10 taking. This allows a particularly high range and measurement accuracy and a high immunity to interference can be achieved.

2 shows ring electrodes 25a . 25c and 25e , which are relatively elongated and substantially rectangular in shape. The re 2 upper ring electrode 25a indicates at its top 27 a contour, which in part to the course of the contour K of the headrest 10 adapted in this area.

The middle ring electrode 25c has fringe-like elongated corner sections 28a and 28b on top of that pair of electrodes 25e and 25f between them. The ring electrode 25c is in this respect formed in the manner of an upside-down U.

Despite the different geometries of the electrodes 25a . 25c . 25e are all electrodes 25a . 25c and 25e each formed as a ring electrode, and surrounded in each case an inner electrode closed annular. This can achieve the high density of E-field lines required to achieve optimal measurement.

With the electrode arrangement of 2 a particularly large and thus advantageous total electrode area can be achieved in the following way:
2 shows an embodiment of a headrest according to the invention with three electrode pairs 25a . 25b ; 25c . 25d ; 25e . 25f ,

According to a first embodiment, the electrode pairs can be acted upon simultaneously or temporally successive in each case with such AC voltage, that the respective ring electrode, for. B. the electrode 25a , on an AC potential and the inner electrode, so z. B. the electrode 25b , is at a counter potential. In this way, through the pair of electrodes 25a . 25b a first measuring field 45a be provided or generated. Through the electrode pair 25c . 25d becomes a second measuring field 45b , and through the pair of electrodes 25e . 25f becomes a third measuring field 45c provided.

The three measuring fields 45a . 45b . 45c lie layer-like, in relation to the vertical direction z overlapping arrangement one above the other and allow both a statement about the vertical position of the head relative to the headrest and a statement about the position of the head relative to the headrest in the vehicle longitudinal direction.

1 makes it clear that the measuring ranges 45a . 45b . 45c each have a range R relative to the vehicle longitudinal direction x, which extends relatively far forward. The range R of the measuring ranges is preferably more than 30 mm, preferably up to 200 mm. This allows a particularly secure detection of the relative head position even in the event that the distance d between the headrest 10 and the head 17 when performing the measurement is large.

The schematic representation of 1a takes into account that the measuring ranges 45a extend relatively far in a vehicle transverse direction y and in particular can be formed as wide as the width of the head 17 in the vehicle transverse direction is typically assumed. In 1a became the width of the measuring range 45a referred to L on the vehicle transverse direction y.

In synopsis of 1 and 1a clearly shows that the measuring areas are formed substantially layered overlapping and superimposed. The overlap area between the measuring ranges 45b and 45c is in 1 denoted by Ü. Due to the overlapping arrangement, a complete detection can be achieved.

The ranges of the different measuring ranges 45a . 45b . 45c can be different. In the embodiment of the invention, the range of the average measuring range is 45b about 10 to 12 cm, with a measurement accuracy of +/- 3 mm is achieved. The upper and lower measuring ranges 45a and 45c show, according to an electrode geometry of 2 , a maximum range of about 6 cm, the measurement is subject to an error of +/- 2 mm.

3a shows the passenger 14 in a representation of 1 , Of particular interest is the course of the rear contour V of the passenger 14 in the area of his head 17 , his neck 46 and his back 16 ,

3b The dashed representation is intended to illustrate that an image of a corresponding contour curve can be made on the basis of individual measuring points, the number of measuring points is arbitrary and depends essentially on the resolution, speed and valence of the electronics.

3c shows in addition to the contour V of the 3b plotted a number of readings 47a . 47b . 47c . 47d . 47e . 47f . 47g . 47h . 47i . 47j , The meaning of these measurements is explained below.

First, it should be noted that the control unit 41 evidenced by the schematic representation of 4 a memory 48 and a register 49 having.

The memory 48 , the registry 49 as well as the control unit 41 can be beneficial in the headrest 10 , alternatively but also in the area of the vehicle seat 13 be arranged.

The memory 48 and the register 49 can be part of the control unit 41 be or separately arranged and assigned to this.

In the store 48 the contour V of a standard passenger is stored. In the embodiment of the 4 contains the memory 48 Comparison values or historical values for the area of the head 17 , for the neck 46 and the back 16 based on values that represent a standard passenger. In an alternative embodiment of the invention is merely the contour of the head 17 and in another alternative embodiment only the contour of the head 17 and the neck 46 arranged. In the following, however, it should be assumed that in the memory 48 Comparison values for the head 17 , the throat 46 and the back 16 are inscribed.

The comparison values may relate advantageously to a standard passenger. This can be determined for example on the basis of a standard height, on the basis of a standard skull diameter, a standard neck diameter or a standard shoulder area. As a result, average values obtainable by evaluating statistics can be used.

It is also conceivable that different comparison values in the memory 48 are inscribed, and these are chosen differently, for example, for different seating positions or backrest positions. Thus, for example, in the event that the vehicle seat is displaced maximally forward, a first contour course V ₁ and, in the event that the vehicle seat is displaced maximally backwards, a second contour course V ₂ apply.

The different set and detected seating positions may allow an indication of the approximate size of the passenger seated on the vehicle seat. Knowing the approximate size of the passenger then a correspondingly suitable standard contour V ₁ and V _{2 could be} selected. Similarly, it is conceivable that an approximate indication of an approximate weight of the passenger is provided by a seat occupancy sensor. The approximate weight indication could equally be related to different contour gradients V ₁ , V _{2 of} different standard passengers.

In the cases described last, it would be necessary to the extent that in the memory 48 the control unit 41 several different sets of comparison values are stored.

In the following it is to be assumed for reasons of a simplified description that in the memory 48 only a contour V is written.

In the embodiment of the 4 are in the store 48 sixteen lines provided. For example, the rows may be labeled vertically from top to bottom with numbers 1 through 16.

The contour curve V is therefore determined by 16 different comparison values. Related to the 4 the contour V is determined by 16 individual values, their value corresponding to the direction of the arrow G-value in 4 varies for the different 16 fields. The G-value pushes in the different line fields of the memory 48 different contour positions of body sections of the standard passenger.

4 moreover schematically shows a register 49 , The registry 49 is designed memory-similar and serves to record measured values 47a . 47b . 47c . 47d . 47e . 47f . 47g . 47h . 47i . 47j , The measured values 47a . 47b . 47c . 47d . 47e . 47f . 47g . 47h . 47i . 47j were measured by performing a measurement to determine the relative head position of the detection device. The measured values can be faulty.

The obtained measured values can be entered in the register 49 be enrolled. Subsequently, a computing unit, not shown, which is part of the control unit 41 is, or is assigned to, a comparison of the measured values obtained 47a . 47b . 47c . 47d . 47e . 47f . 47g . 47h . 47i . 47j with those in the store 48 stored comparison values of the contour V perform. By using suitable algorithms, an automatic comparison can be made in such a way that the measured values 47a . 47b . 47c . 47d . 47e . 47f . 47g . 47h . 47i . 47j the comparison values are assigned so that there is an optimal match. For example, from the in 4 10 measured values are approximated to be reconstructed when the measured values 47a . 47b . 47c . 47d . 47e . 47f . 47g . 47h . 47i . 47j be moved to the contour V or set in a relationship to the contour V such that the deviations of the measured values obtained from the comparison values of the contour V in the sum are minimized.

By making a corresponding comparison, it is possible to make a statement about the contour profile of the actual, real passenger located in the passenger seat, independently of measured value distortions. The information obtained in this way can complement the measurements and provide a qualitatively improved statement about the actual relative position of the passenger's head and allow an optimized displacement and tracking of the headrest in an optimized relative position.

In addition, it should be noted that the headrest according to the invention preferably performs an automatic detection of the relative position of the head relative to the headrest and subsequently automatically performs a tracking of the headrest in a relation relative to the head relative position. In an alternative embodiment of the invention can also be provided that the detection device detects a relative headrest position and in the event that this is unfavorable, for example because the relative distance in the vehicle longitudinal direction or in the vertical direction is too large or too small, the passenger an optical or outputs an acoustic signal so that it can perform a displacement of the headrest in an optimal position manually or manually initiated.

Claims (20)

Headrest ( 10 ) for a vehicle seat, with a detection device with which a position of a head ( 17 ) of a passenger located on the vehicle seat is detectable relative to the headrest, characterized in that on the headrest an electrode arrangement ( 21 ) is arranged, which for determining the relative distance (d) of the head from the headrest in the vehicle longitudinal direction (x) a plurality of layers in the vertical direction superimposed measuring ranges ( 45a . 45b . 45c ) trains. Headrest for a vehicle seat according to claim 1, characterized in that the relative distance (d) of the head from the headrest in the vehicle longitudinal direction (x) and / or in the vertical direction (z) for the individual measuring ranges ( 45a . 45b . 45c ) can be determined individually. Head restraint for a vehicle seat according to claim 1 or 2, characterized in that the electrode arrangement ( 21 ) at least three vertically spaced pairs ( 25a . 25b ; 25c . 25d ; 25e . 25f ) of electrodes. Head restraint for a vehicle seat according to one of the preceding claims, characterized in that the measuring ranges ( 45a . 45b . 45c ) each having a measurement range (R) in the vehicle longitudinal direction (x) forward, which is starting from the front of the headrest at least 30 mm, in particular at least 40 mm, more preferably at least 50 mm, more preferably at least 60 mm. Headrest for a vehicle seat according to one of the preceding claims, characterized in that the measuring ranges are aligned along parallel planes and / or formed in the vertical direction at least partially overlapping. Headrest for a vehicle seat according to one of the preceding claims, characterized in that the detection device at the same time makes a measurement of the distance (d) of the head from the headrest in the vertical direction and a measurement of the relative distance in the vehicle longitudinal direction (x). Headrest ( 10 ) for a vehicle seat, with a detection device with which a position of a head ( 17 ) of a passenger seated in the vehicle seat ( 14 ) relative to the headrest in the vertical direction (z) and / or in the vehicle longitudinal direction (x) is detectable as a result of a measurement carried out, characterized in that in a memory ( 48 ) of the detection device comparison values are arranged, which have a profile (V) of the contour of body sections ( 17 . 46 . 16 ) of a human ( 141 ), and which can be used for the purpose of comparison with the measured values obtained when performing a measurement. Headrest ( 10 ) for a vehicle seat, with a detection device with which a position of a head ( 17 ) of a passenger seated in the vehicle seat ( 14 ) is detectable relative to the headrest in the vertical direction (z) and / or in the vehicle longitudinal direction (x), characterized in that the detection device performs a calibration measurement, controlled by a first event, before the passenger ( 14 ), And that the detection device subsequently, controlled by a second event or timed, a measurement for determining the position of the head ( 17 ) relative to the headrest ( 10 ). A headrest for a vehicle seat according to claim 8, characterized in that the first event is provided or derived from an opening of the door of the vehicle. Headrest for a vehicle seat according to claim 8 or 9, characterized in that the second event of an actuation of Engine ignition or closing a seat belt or by engaging a gear or by reaching a minimum speed is provided or derived Headrest ( 10 ) for a vehicle seat, with a detection device with which a position of a head ( 17 ) of a passenger seated in the vehicle seat ( 14 ) relative to the headrest ( 10 ) in the vertical direction (z) is detectable, characterized in that with the detection device and the distance (d) of the head relative to the headrest ( 10 ) in the vehicle longitudinal direction (x) is detectable, and that the detection device is a measurement of the distance (d) of the head ( 17 ) from the headrest ( 10 ) in the vertical direction (z) at the same time as a measurement of the distance of the head from the headrest in the vehicle longitudinal direction (x) makes. Headrest for a vehicle seat according to one of Claims 7 to 11, characterized in that the detection device has an electrode arrangement arranged on the headrest ( 21 ) assigned. Head restraint for a vehicle seat according to claim 12, characterized in that the electrode arrangement ( 21 ) a plurality of vertically spaced apart (z) pairs ( 25a . 25b ; 25c . 25d ; 25e . 25f ) of electrodes and / or a plurality of layer-like in the vertical direction superimposed measuring ranges ( 45a . 45b . 45c ) trains. Headrest for a vehicle seat according to one of the preceding claims, characterized in that the detection device comprises a control unit ( 41 ), which derives the distances of the head from the headrest in both the vertical and in the vehicle longitudinal direction from the measurement results of only one measurement of the detection device. Head restraint for a vehicle seat according to one of claims 1 to 6 or 12 to 14, characterized in that at least one pair of electrodes comprises a first electrode (10). 25a ) having a second electrode ( 25b ) surrounds annularly closed. Headrest for a vehicle seat according to one of the preceding claims, characterized in that the headrest ( 10 ) in the height (z) and in the vehicle longitudinal direction (x) is adjustable. Headrest for a vehicle seat according to one of the preceding claims, characterized in that the headrest by means of a motor drive ( 44 ) is adjustable. Head restraint for a vehicle seat according to one of claims 1 to 6 or 12 to 17, characterized in that the electrode arrangement ( 21 ) near the front ( 18 ) of the headrest is arranged. Headrest for a vehicle seat according to one of the preceding claims, characterized in that the detection of the relative head position takes place with the aid of capacitive measurements. Head restraint for a vehicle seat according to one of claims 1 to 6 or 12 to 19, characterized in that between the two electrodes ( 25a . 25b ) of a pair of electrodes an AC voltage can be applied.

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