Combined sensor and heating element

Combined sensor and heating element

initiation

The present invention relates to a combined sensor and heating element, in particular for use in a vehicle seat.

Modern vehicles are increasingly being equipped with eg so-called seat occupancy sensors that prevent an accident triggering of a specific vehicle seat assigned airbags if the corresponding vehicle seat is not occupied. Such seat occupancy sensors often include a sensor mat with a plurality of pressure sensitive areas, which are interconnected by flexible connection strips. The sensor mat is integrated into the vehicle seat in such a way that the pressure sensitive areas are distributed over the seat surface of the vehicle seat.

The increased comfort demands of consumers also lead to more and more vehicle seats are equipped with seat heating. Such a seat heater generally comprises a heating mat of an embedded heating conductor in two layers of nonwoven fabric. Also, such a heating mat is integrated in the seat of the vehicle seat, so that the heat conductor extends substantially over the entire seat surface of the vehicle seat.

In the case of vehicle seats, which are both equipped with a seat occupancy sensor as well as with a seat heater, the sensor mat and the mat prior to installation in the seat are combined to form a combined sensor and heating element. The preparation of such a combined sensor and heating element is, however, relatively expensive, since the two functional elements are initially produced separately and then have to be fixed to each other.

Object of the invention

Object of the present invention is thus to propose a simplified combined sensor and heating element.

General Description of the Invention

This object is achieved by a combined sensor and heating element, with a sensor mat with multiple active areas that are interconnected by flexible connecting strip, and a heat conductor, the heat conductor is applied directly onto the flexible connection strips of the sensor mat. In this sensor and heating element of the heating conductors need not be embedded separately in a manageable nonwoven laminate accordingly, which is then subsequently fixed on the sensor mat. The preparation of such a combined sensor and heating element thus requires significantly fewer steps than the production of conventional entry modules. Moreover, the cost of materials for the production of the functional element according to the invention is less than is the case with conventional functional elements. The combined sensor and heating element of the present invention therefore represents a particularly simple and inexpensive entry module.

It should be noted that the active areas of the sensor mat may comprise pressure-sensitive areas, which means that, for example, alter the electrical characteristics of the active regions as a function of the force exerted on the force sensor by weight. In another embodiment, the active regions may also include simple switching elements, only between two states such as "occupied" and "not occupied" different. Moreover, it is irrelevant to the present invention, if the sensor function of the sensor and heating element for easy detection of a seat occupancy or for classifying a person incarcerated in the seat according to the invention is used. In other words, the sensor mat can be both a simple seat occupancy sensor and a sensor for receiving and evaluating a pressure profile pose.

In the case of a simple seat occupancy sensor, which generally extends only over the actual seat surface of the seat, this additional flexible strip may have, extending over the Seitenwulste of the seat. Such flexible strips can be easily punched out from a carrier film with the sensor and are therefore easy to manufacture. The heat conductor extends advantageous also this additional sensor strips, so that the Seitenwulste the seat are heated. It should be noted that in the additional strips no active areas of the seat occupancy sensor must be arranged.

In an advantageous embodiment of the invention, the heat conductor is covered by a protective layer. This protective layer may comprise, for example, plastic film or a nonwoven layer which is preferably laminated onto the flexible connection strips of the sensor mat.

The heat conductor itself may be adhered or printed onto the flexible connection strips of the sensor mat. In the latter case, the heat conductor has, for example, a semiconductor ink to be applied in a Serigraphieverfahren to the connection tracks.

In a particularly advantageous embodiment of the heating conductor has a resistance material having a positive temperature coefficient. Such materials exhibit resistance at high temperatures a higher electrical resistance than at low temperatures. With a suitable choice of material, this effect can be exploited to limit the heating current, so that a complex downstream temperature control for the heating element can be omitted.

The electrical connections of the sensor mat and the electrical connections of the heat conductor are preferably disposed on a same terminal lug of the combined sensor and heating element. This creates a contact between the two separate functions made possible by a single plug element and thus substantially simplifies the subsequent assembly. In one possible embodiment, the two separate functional elements can be for example connected to a common electronics.

This electronics is then used both for evaluating the sensor mat as well as the supply and power control of the heating mat. An intelligent control system can prevent the seat heating is switched on when the respective seat is not occupied this example.

In a common evaluation and supply circuit for the sensor mat and the mat, the heating control is preferably carried out in pulsed and offset relative to the sensor interrogation time. As a result, on the one hand be better utilized the power of the analysis and supply electronics, on the other hand mutual interference between the two systems are largely excluded.

Description with reference to FIGS

In the following, an embodiment of the invention based on the accompanying figures will be described. Shown are:

Fig.1: is a section through an embodiment of a combined sensor and heating element;

Fig.2: is a plan view of an embodiment of a combined sensor and heating element.

Seat occupancy sensors or sensors for recording or evaluating a seat profile are often constructed as a pressure-sensitive surface sensors in film design. Such a seat occupancy sensor generally comprises a plurality of active areas that are distributed over a certain surfaces and are interconnected by flexible connecting webs of the sensor. Such a sensor is shown in Figures 1 and 2, wherein Fig. 1 is a section through an active region of the sensor.

The sensor comprises a first and a second carrier foil 12 and 14 that are laminated by means of a spacer 16, for example a double-sided adhesive sheet together. 16 In the area of ​​the active regions 18 of the sensor 10, the spacer has a recess 20, so that in this area the two carrier foils face 12 and 14 apart.

In the active region 18 of the sensor 12 and 14 contact arrangements 22 and 24 are arranged between which at the pressing together of the two carrier foils, an electric contact is made on the inside of the carrier foils. The contact assemblies 22 and 24 can for example comprise electrode structures, wherein at least one of the contact assemblies also comprises a layer of a pressure sensitive material. The contact arrangements are applied in a screen printing process on the corresponding surfaces of the carrier foils, for example, prior to the laminating of the carrier foils.

From the sandwich structure thus prepared areas are then cut out, in which no active areas of the sensor are arranged so that flexible connecting webs 26 are formed (see FIG. 2) within which the active regions 18 of the seat occupancy sensor 10 are disposed and within which the electrical connection lines run for the active regions.

In the present seat occupancy sensor 12, a heat conductor 28 is applied to the outer side of the carrier foil, which extends along the flexible connecting tracks of the sensor. The course of the heating follows advantageously the connecting tracks such that a good coverage of the heating is achieved 28th The two ends 30 of the continuous heating conductor 28 preferably extend to a terminal lug 32, which also receives the electrical connections of the contact arrangements of the active regions of the seat occupancy sensor. In this way a connection of the heating at a heating current source and connect the contact arrangements to evaluation by means of a single plug element allows.

The heat conductor 28 is applied directly to the carrier film 12; it can be applied for example by a screen printing method on the carrier film 12. In this case, the heating element has, for example a semiconductor ink.

It is to be noted that the heat conductor is preferably covered on the carrier film 12 after application with a (not shown) protective layer. This protective layer may advantageously comprise a plastic film or, alternatively, a nonwoven layer which can be glued to the base sheet 12.

If the sensor mat for easy detection of a seat occupancy or for classifying a person incarcerated in the seat is used, this has generally active regions in the area of ​​the seat and thus also Seitenwulste flexible connecting tracks, which extend over the Seitenwulste. In the case of a simple seat occupancy sensor, which generally extends only over the actual seat surface of the seat, the sensor may comprise additional flexible strips extending over the Seitenwulste of the seat. Such flexible strips can be easily punched out from a carrier film with the sensor and are therefore easy to manufacture. The heat conductor extends advantageous also this additional sensor strips, so that the Seitenwulste the seat are heated. It should be noted that in the additional strips no active areas of the seat occupancy sensor must be arranged. Furthermore, the flexible strips do not need to be punched out of a sandwich structure but it is sufficient that only has that support film, to which the heating conductor is applied, such strips.