TITLE

A photo radiation intensity sensor TECHNICAL FIELD

The invention relates to a photo radiation intensity sensor comprising a housing, a lid part and at least two sensor elements. The sensor elements are sensitive to radiation and are placed on a circuit board having a first side and a second side. The sensor elements are arranged to produce output signals for estimating the sun radiation heating impact. The photo radiation intensity sensor comprises a diffusive compound that is a potting, which compound is positioned between the lid part and said sensor elements. The photo radiation intensity sensor comprises at least one shading element positioned between said sensor elements.

BACKGROUND ART

Fully automated climate systems in vehicles are commonly used in vehicles. Originally such climate systems use single or multiple temperature sensors sensing the temperature in the cabin and regulate the airflow in dependence of the temperature measured by said sensors. However, the influence of the radiation of the sun is not adequately compensated for when using only a temperature sensor. Therefore it has been suggested to make use of radiation sensors, which measures the impact of the sun.

Further improvements have resulted in sensors, which identifies the position of the sun in relation to the vehicle in order to further improve the regulation of the climate unit. Such a sensor arrangement is known from US 7157678, which discloses multiple sensor elements arranged in a housing, where said sensor elements are sensitive to light. The sensor elements are arranged at different geometrical positions of the sensor housing, more precisely at opposite sides of a printed circuit board which extends into the housing, towards a transparent or translucent lens element. The housing has a chamber containing a diffusive compound. However, such an arrangement has a disadvantage in its inherent size, which presents a protrusion where it is placed. An example of such a placement is the dashboard, where such a protrusion is undesirable of design reasons.

SUMMARY

It is an object of the present invention to provide a vehicle radiation sensor with a plurality of sensor elements that requires less visible space in relation to prior radiation sensors.

Said object is achieved by means of a photo radiation intensity sensor comprising a housing, a lid part and at least two sensor elements. The sensor elements are sensitive to radiation and are placed on a circuit board having a first side and a second side. The sensor elements are arranged to produce output signals for estimating the sun radiation heating impact. The photo radiation intensity sensor comprises a diffusive compound that is a potting, which compound is positioned between the lid part and said sensor elements. The photo radiation intensity sensor comprises at least one shading element positioned between said sensor elements. Said sensor elements are positioned on the first side of the circuit board, the first side facing the lid part and the second side facing away from the lid part.

According to an example, the photo radiation intensity sensor includes a radiation filter transparent to a defined frequency interval. The radiation filter is arranged to block radiation outside said frequency interval from impinging on the sensor elements. In an option, the radiation filter is constituted by the diffusive compound. In an option the radiation filter includes a lens element.

According to another example, the sensor elements are sensitive to infrared and/or visible light.

According to another example, the diffusive compound is a liquid or a gel. According to another example, the shading element is in the form of walls which extend away from the first side of the circuit board towards the lid part when mounted, each wall being positioned between two adjacent sensor elements. The walls are for example positioned in the form of a cross.

According to another example, the shading element extends away from the first side of the circuit board towards the lid part and has a cross-section perpendicular to this extension which is a polygon or circular. According to another example, at least one light emitting diode arrangement is mounted to the first side of the circuit board, each light emitting diode arrangement being positioned such that it correspond to a corresponding symbol. Said symbol is visible when the corresponding light emitting diode arrangement is activated and illuminates the symbol.

According to another example, a rigid foil is positioned between the lid part and the sensor elements, where the diffusive compound is positioned between the sensor elements and the foil. Other examples are disclosed in the dependent claims.

Other examples and embodiments are described herein and would be understood by one of skill in the art upon reading the present disclosure. These and other embodiments, aspects, advantages, and features of the present invention will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art by reference to the following description of the invention and referenced drawings or by practice of the invention. The aspects, advantages, and features of the invention are realized and attained by means of the instrumentalities, procedures, and combinations particularly pointed out in the appended claims and their equivalents.

A number of advantages are provided by means of the present invention, for example: - Less space required; and

- Enables illuminable symbols to be formed in the lid part. BRIEF DESCRIPTION OF DRAWINGS

Embodiments of the invention will be described in detail below, with references to appended drawings where:

FIG. 1 shows an exploded view of a first embodiment of an optical radiation intensity directional sensor;

FIG. 2 shows a top view of the first embodiment of an optical radiation intensity directional sensor;

FIG. 3 shows a cross-sectional view of the optical radiation intensity directional sensor in Figure 2;

FIG. 4 shows a cross-sectional view of a second embodiment of an optical radiation intensity directional sensor;

FIG. 5 shows a cross-sectional view of a third embodiment of an optical radiation intensity directional sensor;

FIG. 6 shows a cross-sectional view of a fourth embodiment of an optical radiation intensity directional sensor;

FIG. 7 shows a cross-sectional view of a fifth embodiment of an optical radiation intensity directional sensor;

FIG. 8 shows an exploded view of a sixth embodiment of an optical radiation intensity directional sensor; and FIG. 9 shows an exploded view of a seventh embodiment of an optical radiation intensity directional sensor.

DETAILED DESCRIPTION

In the following detailed description, reference is made to the accompanying drawings which form a part hereof, and in which is shown by way of illustration specific embodiments in which the invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the invention, and it is to be understood that other embodiments may be utilized and that structural changes may be made without departing from the scope of the present invention. Therefore, the following detailed description is not to be taken in a limiting sense, and the scope of the present invention is defined by the appended claims and their equivalents. Figure 1 shows an exploded view of a first embodiment of an optical radiation intensity directional sensor 1 , Figure 2 shows a top view of said sensor, and Figure 3 shows a section of Figure 2. The directional sensor 1 comprises a housing 2 having an opening 3 which is covered by a lens element 4 when mounted. The lens element 4 is transparent or translucent, and also functions as a lid that is snapped into place by means of snap-lock attachment means 18, 19.

Here, the lens element 4 functions as a radiation filter being transparent to radiation within a well-defined frequency interval. The housing 2 of the optical radiation intensity directional sensor 1 is in the shown embodiment formed by outer walls 5a, 5b, 5c, 5d forming an internal chamber 6.

The sensor 1 further comprises an array of sensor elements 7a, 7b, 7c, 7d, constituted by a first sensor element 7a, a second sensor element 7b, a third sensor element 7c and a fourth sensor element 7d, the sensor elements 7a, 7b, 7c, 7d being positioned between the housing 2 and the lens element 4 when mounted. The sensor 1 comprises a diffusive compound 8, indicated with a grainy structure in Figure 3, positioned between said lens element 4 and said array of sensor elements 7a, 7b, 7c, 7d. The diffusive compound 8 is preferably a potting in the form of a liquid or a gel, which has been filled into the lens element 4 in an upside-down position before mounting to the housing 2, and then the lens element 4 is mounted to the housing 2 in this position (not shown).

Preferably, the compound 8 is more or less liquid in order to enable the filling into the lens element 4, and may be of such a composition that it cures when the filling procedure is completed. The curing may be of such a nature that the compound, being a liquid of a relatively low viscosity, cures to a liquid of higher viscosity, for example a gel. The curing may also result in a solid compound.

The array of sensor elements 5 is placed on a circuit board 9 having a first side 9a and a second side 9b. As shown in Figure 3, the walls 5a, 5b, 5c, 5d of the housing 2 do not extend past the circuit board 2 towards the lens element 4 when mounted in the housing, the circuit board closing the opening 3 in the housing 2 when mounted. This results in the filling procedure for the diffusive compound described above, filling the diffusive compound into the upside-down lens element 4.

Alternatively, the housing 2 may have walls extending past the circuit board 9 towards the lens element 4 when mounted, such that the diffusive compound may be filled directly into the part of the chamber 6 that is positioned above the circuit board, flooding this part of the chamber 6, and not into the lens element 4. The lens element 4 may here be mounted afterwards. The diffusive compound may also be filled such that it flows beneath the circuit board 9 as well, flooding the chamber 6.

According to the present invention, all sensor elements 7a, 7b, 7c, 7d are positioned on the first side 9a of the circuit board 9, the first side 9a facing the lens element 4 and the second side 9b facing away from the lens element 4. Furthermore, a shading element 10 is positioned between the sensor elements 7a, 7b, 7c, 7d, here in the form of walls 10a, 10b, 10c 10d which are formed in one piece in the form of a cross, where the walls extend away from the first side 9a of the circuit board 9 towards the lens element 4 when mounted. Each wall 10a, 10b, 10c 10d is positioned between two adjacent sensor elements 7a, 7b, 7c, 7d such that all adjacent sensor elements 7a, 7b, 7c, 7d are separated by a wall 10a, 10b, 10c 10d. The shading element 10 is here a part of the housing 2 that is arranged to extend through a corresponding aperture 1 1 in the circuit board 9 when mounted, the shading element 10 thus not constituting a separate part.

The shading element 10 at least partly blocks light from impinging directly on one of two sensor elements within said array of sensor elements 7a, 7b, 7c, 7d separated by said shading element 10. Thereby four different regions, which are separated from being simultaneously exposed to directly impinging sunlight, are created.

The shading element 10 is arranged to prevent exposure of radiation of the sensor elements separated by the shading element 10 to a degree depending of the position of the photo radiation intensity directional sensor in relation to a source of photo radiation, such as the sun. In an option, the shading element 10 is thereby arranged for creating differences in output amplitudes from the sensor elements 7a, 7b, 7c, 7d which difference in amplitude is used for estimating the position of the source of radiation.

Each sensor element 7a, 7b, 7c, 7d produces an output signal also when respectively sensor element is positioned in a position inside said housing 2 where light would not impinge on the sensor element in the absence of the diffusive compound 8.

Furthermore, a first light emitting diode arrangement 12, a second light emitting diode arrangement 13 and a third light emitting diode arrangement 14 is mounted to the first side 9a of the circuit board 9. The light emitting diode arrangements are positioned such that they correspond to symbols 15, 16 (only two symbols schematically indicated with dotted lines in Figure 2) printed in, or on, the lens element 4 when the lens element 4 is mounted. In this way, a symbol 15, 16 is visible when the corresponding light emitting diode arrangement 12, 13, 14 is activated and illuminates the symbol 15, 16, otherwise the symbol 15, 16 is not visible. The symbols 15, 16 are masked from each other such that light from not corresponding light emitting diode arrangements 12, 13, 14 does not cause an undesired illumination of a symbol. The symbols 15, 16 may refer to a warning system of the vehicle, or a communication system, for example indicating low outer temperature, vehicle malfunction or the presence of an e-mail or an SMS (Short Message Service). By means of the diffusive compound, which also covers the light emitting diode arrangements, the illumination of each symbol is softened, making it more comfortable to look at. The symbols 15, 16 may be printed to, and/or moulded into the lens element 4.

In a second embodiment and third embodiment, with reference to Figure 4 and Figure 5, showing similar views as in Figure 3, the lens element 4', 4" have different shapes, such that light is refracted in desired ways towards the sensor elements 7a, 7b, 7c, 7d. In the second embodiment, the lens element 4' comprises a raised flat area 28 above the sensor elements 7a, 7b, 7c, 7d. In the third embodiment, the lens element 4" comprises a domed area 29 above the sensor elements 7a, 7b, 7c, 7d.

With reference to Figure 6, showing a fourth embodiment, a similar view in as Figure 3 is shown. Here, a transparent and/or translucent rigid foil 17 is used as a mould for the diffusive compound 8', which is filled into the rigid foil 17 in an upside-down position before being mounted to the housing 2. By means of the foil 17, a space between the foil 17 and the lens element 4 is not filled the diffusive compound 8' when the components are mounted, the space between the circuit board 9 and the lens element 4 being less occupied of the diffusive compound. In this way, a greater freedom of design for the lens element 4 is acquired. Furthermore, the symbols discussed above may be printed in or on the foil 17 instead of at the lens element 4.

With reference to Figure 7, showing a similar view as in Figure 6, a fifth embodiment with an alternative foil 20 is shown, also here used as a mould for the diffusive compound 8". The main difference lies in a folded ridge 21 in the foil 20, where the folded ridge 21 acts as a shading element between the sensor elements. Although not explicitly shown in Figure 7, the folded ridge is here cross-shaped such that a cross-shaped shading element mainly equivalent to the one shown in Figure 1 is acquired. Here, the shading element is thus not part of the housing, but is instead art of the foil 20. A foil is cheap and easily formed and thus enables to have a potted area of any desired form which in the final product is hidden with a translucent protective/aesthetic top such as a lens element and/or lid.

A foil enables the shadowing element or/and the illuminable symbols 15, 16 to be formed in a very cost-effective way by just printing them on the surface of the foil 20, maybe even before its formed, when it is still flat. This print may be formed as a light- blocking layer 30, where appropriate openings are made for sensor elements 7c, 7d, the possibly being part of the shading element 21 . The symbols 15, 16 may be printed as a part of the light-blocking layer 30, in openings for the light emitting diode arrangements 12, 14. Alternatively, the symbols 15, 16 may be constituted by openings in the light-blocking layer 30. If the symbols 15, 16 are formed in the lens element 4, only openings in the light-blocking layer 30 are needed.

Although the light-blocking layer 30 is shown to be formed on the side of the foil 20 that faces the lens element 4 when mounted, the light-blocking layer might just as well be formed on the other side of the foil 20, or both sides.

In Figure 8, an alternative optical radiation intensity directional sensor V, constituting a sixth embodiment, is shown, having an alternative shading element 22. The alternative shading element 22 is in the form of a rhomboid having four sides 22a, 22b, 22c, 22d along which corresponding sensor elements 7a', 7b', 7c', 7d' are mounted on the circuit board 9'. The shading element 22 runs through a corresponding aperture 25 in the circuit board 9'. In Figure 9, an alternative optical radiation intensity directional sensor 1 ", constituting a seventh embodiment, is shown, having an alternative shading element 23. The alternative shading element 23 is in the form of a cylinder having a circumferential wall 24 along which the sensor elements 7a", 7b", 7c", 7d" are evenly distributed and mounted on the circuit board 9". The shading element 23 runs through a corresponding aperture 26 in the circuit board 9".

Generally, the invention relates to a photo radiation intensity sensor 1 comprising a housing 2, a lens element 4 constituting a lid part, and at least two sensor elements 7a, 7b, 7c, 7d sensitive to radiation which are placed on a circuit board 9 having a first side 9a and a second side 9b. The sensor elements 7a, 7b, 7c, 7d are arranged for producing output signals which are used for estimating the sun radiation heating impact. The photo radiation intensity sensor 1 comprises a diffusive compound 8 positioned between the lens element 4 and said sensor elements 7a, 7b, 7c, 7d, where at least one shading element 10 is positioned between said sensor elements 7a, 7b, 7c, 7d. The said sensor elements 7a, 7b, 7c, 7d are positioned on the first side 9a of the circuit board 9, the first side 9a facing the lens element 4 and the second side 9b facing away from the lens element 4.

The invention has been described with reference to various specific and preferred embodiments and techniques. However, it should be understood that many variations and modifications may be made while remaining within the spirit and scope of the invention.

For example, the following compounds may be used as diffusive compound: Wacker SilGel 612 with small quantity of Elastosil white colour paste FL; Wacker SilGel 612 is of two liquid components (A and B), which together cure to gel of high optical transparency; when adding small amount of Elastosil white colour paste FL (0.1 % to 1 % by weight) this gel becomes opaque ("milky") with good diffusive properties of optical radiation; concentration of this paste also can be used for control of sensitivity of sensor in aggregate: when increasing percentage of paste-sensitivity decreases and vice versa. Wacker SilGel 612 is a two part crosslinking silicone rubber. Elastosil is a mixture of pigments and a reactive silicone polymer. Both are trademarks of Wacker.

[0037] In FIG. 1 1 , a diagram of sensitivity versus concentration of white paste in compound. Tests has shown that a concentration between 0.1 %-1 % provides adequate degree of opaqueness for providing uniform output level for a single sensor body without reducing the output level too much. In an embodiment, the concentration is in between about 0.1 % and 1 %. As a further example, the optical radiation intensity sensor may include a radiation filter transparent to a defined frequency interval, which radiation filter is arranged to block radiation outside said frequency interval from impinging on the sensor elements. The radiation filter is according to one embodiment of the invention formed by the diffusive compound. In an alternative embodiment the lens element is provided with a filtering capacity, which can be obtained by choice of material of the lens element or by arranging a cover sheet of a filtering material on the lens element. A further possibility is to include a separate second lens element. In an embodiment, the sensor element should be sensitive in the infrared region. The optical radiation intensity directional sensor may be equipped with a separate lid, which facilitates the freedom of design of parts of the optical radiation intensity directional sensor, which are visible after mounting of the optical radiation intensity directional sensor in a vehicle. The shading element in the form of a cross is especially suited for four sensor elements, if there are less or more than four sensor elements in the photo radiation intensity sensor 1 , other shapes of the walls are of course suitable. Other configurations and patters of the sensor elements are also conceivable, which of course also affects the position and shape of the shading element or shading elements. Other shapes of shading elements are thus conceivable. A shading element should be arranged such that shade may produced for every sensor element depending on the position of the sun or other light source.

The rhomboid shading element 22 may generally have polygonal cross-section.

In Figure 7, Figure 8 and Figure 9, the shading elements are part of corresponding housings, extending through matching apertures on the respective circuit board. In these and all other cases, the shading element may be constituted by a separate element that is mounted to the circuit board, for example by means of an adhesive. The shading element may be constituted by several separate parts or shading sub- elements. Any type of shading element may be made in the foil 17, 20. In the shown embodiments, the sensor elements are exposed to the liquid, which may have a protective quality reducing oxidation of the sensor elements 7a, 7b, 7c, 7d. The printed circuit 9 board may carry further electronic circuits which also are protected from negative influence on the environment by the diffusive compound. The lens element is generally constituted by a lid part.

A connector part 27 is suitably attached to the circuit board to enable contact between the circuit board and other electric and/or electronic parts (not shown).

In the drawings, Figure 2 should be regarded as schematic, mainly indicating where the section is made. For example, the different shapes of the lens element indicated in Figure 4 and Figure 5 are not explicitly shown in Figure 2.