TEMPERATURE SENSOR DEVICE FOR A WINDSHIELD OF A VEHICLE

Abstract

A temperature sensor device for sensing a temperature of a windshield of a vehicle includes a single printed circuit board having a circuitry, a temperature sensor mounted on the printed circuit board, and a thermally conductive pad attached to the temperature sensor. The thermally conductive pad is arranged to thermally and mechanically directly contact the windshield.

Claims

1. A temperature sensor device for sensing a temperature of a windshield of a vehicle, comprising: a single printed circuit board having a circuitry; a temperature sensor mounted on the printed circuit board; and a thermally conductive pad attached to the temperature sensor and arranged to thermally and mechanically directly contact the windshield.

2. The temperature sensor device of claim 1, wherein the circuitry is a measurement and control circuitry.

3. The temperature sensor device of claim 1, wherein the temperature sensor is a thermistor.

4. The temperature sensor device of claim 1, wherein the printed circuit board has a tab portion, the temperature sensor is mounted to the tab portion.

5. The temperature sensor device of claim 4, wherein the thermally conductive pad is attached to the tab portion.

6. The temperature sensor device of claim 5, wherein the thermally conductive pad is attached to an edge of the tab portion.

7. The temperature sensor device of claim 1, wherein the printed circuit board has a plurality of electrically and thermally conductive lines arranged to receive a heat flow from the windshield.

8. The temperature sensor device of claim 7, wherein the electrically and thermally conductive lines are copper lines.

9. The temperature sensor device of claim 7, wherein the temperature sensor is in thermal contact with at least some of the electrically and thermally conductive lines.

10. The temperature sensor device of claim 1, wherein the printed circuit board has a plurality of openings arranged between portions of the circuity and the temperature sensor.

11. The temperature sensor device of claim 1, wherein the temperature sensor is soldered to the printed circuit board.

12. The temperature sensor device of claim 1, wherein the printed circuit board is a non-flexible printed circuit board.

13. The temperature sensor device of claim 1, further comprising an attachment device attaching the temperature sensor device to the windshield.

14. The temperature sensor device of claim 13, wherein the attachment device has a portion arranged and configured to conduct heat emitted by the circuitry away from the temperature sensor.

15. The temperature sensor device of claim 14, wherein the attachment device is a clip member including a metal material.

16. The temperature sensor device of claim 15, wherein the portion arranged and configured to conduct heat emitted by the circuitry away from the temperature sensor is a part of the clip member.

17. A defogging control device or a wiper operation control device for a motor vehicle having a windshield, the defogging control device or wiper operation control device comprising: a humidity sensor device sensing a humidity of the windshield; and a temperature sensor device sensing a temperature of the windshield, the temperature sensor device including a single printed circuit board having a circuitry, a temperature sensor mounted on the printed circuit board, and a thermally conductive pad attached to the temperature sensor and arranged to thermally and mechanically directly contact the windshield.

18. A method of attaching a temperature sensor device to a windshield of a vehicle, comprising: providing a bracket member at the windshield or a rearview mirror installed in the vehicle; providing the temperature sensor device including a single printed circuit board having a circuitry, a temperature sensor mounted on the printed circuit board, and a thermally conductive pad attached to the temperature sensor; and fastening the temperature sensor device to the bracket member such that the thermally conductive pad thermally and mechanically directly contacts an inner surface of the windshield directed toward a compartment of the vehicle.

19. The method of claim 18, wherein the printed circuit board has a plurality of electrically and thermally conductive lines.

20. The method of claim 19, wherein the temperature sensor device is fastened to the bracket member such that at least some of the plurality of electrically and thermally conductive lines are in thermal contact with the windshield.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The invention will now be described by way of example with reference to the accompanying Figures, of which:

[0010] FIG. 1 is a sectional side view of a temperature sensor device according to an embodiment and a part of the temperature sensor device; and

[0011] FIG. 2 is a sectional side view of a temperature sensor device according to another embodiment.

DETAILED DESCRIPTION OF THE EMBODIMENT(S)

[0012] Features and advantages of the present invention will be described in detail below with reference to the drawings. In the description, reference is made to the accompanying figures that are meant to illustrate embodiments of the invention. It is understood that such embodiments do not represent the full scope of the invention. All embodiments described herein are not intended as limitations but serve as examples illustrating features and advantages of the invention. It is to be understood that some or all of the described features can also be combined in different ways.

[0013] A temperature sensor device 10 according to an embodiment is shown in FIG. 1. The temperature sensor device 10 includes a printed circuit board (PCB) 1 encased in a housing 2. Some circuitry 3 is formed on the PCB 1. The circuitry 3 comprises circuitry elements used for data processing and sensor control.

[0014] The PCB 1, as shown in FIG. 1, has a tab portion 1a. In the shown embodiment, the PCB 1 is a single, non-flexible, i.e. rigid, PCB that cannot be bent or rolled up significantly without breakage. The bend radius of the PCB 1 used herein may, in particular, be below 1 mm.

[0015] A temperature sensor 4 is attached to the tab portion 1a as shown in FIG. 1. Thereby, the temperature sensor 4 is directly mounted to the PCB 1. For example, the temperature sensor 4 is soldered to the tab portion 1a. In fact, the temperature sensor 4 can be soldered to the tab portion 1a of the PCB 1 within the process of soldering all or some of the other electronic components of the circuitry 3 (during some reflow processing, for example) to the PCB 1. The circuitry 3 may comprise a measurement and control circuitry for processing data sensed by the temperature sensor 4 and for controlling the temperature sensor 4.

[0016] According to an embodiment, the temperature sensor 4 is a thermistor. The thermistor can be a Negative Temperature Coefficient (NTC) thermistor that is characterized by a resistance decreasing exponentially with the sensed temperature. The NTC thermistor may be made based on polycrystalline oxide ceramics, in particular, exhibiting a crystal structure that is basically a spinel structure resulting from a sintering process.

[0017] In another embodiment another sensor, for example, a humidity sensor may be additionally mounted on the PCB 1.

[0018] In order to sense the temperature of a windshield 5 of a vehicle, a reliable thermal contact to the windshield 5 has to be provided. As shown in FIG. 1, the thermal contact is provided by a thermally conductive pad 6 connected to the temperature sensor 4. The thermally conductive pad 6 may be made of or comprise a noble metal, for example, gold or copper or some alloy thereof.

[0019] The thermally conductive pad 6 is attached to the temperature sensor 4 and arranged to thermally and mechanically directly contact an inner surface of the windshield 5. In an embodiment, the thermally conductive pad 6 may be attached to an edge of the tab portion 1a of the PCB 1. The temperature sensor 4 does not need to directly contact the windshield 5 but rather the contact is made via the thermally conductive pad 6. Thereby, a degradation of the temperature sensor 4 during the lifetime can be reduced. The housing 2 has an extension 2a corresponding to the thermally conductive pad 6 that may also contact the windshield 5.

[0020] In order to attach the temperature sensor device 10 to the windshield 5, an attachment device 7 is provided as shown in FIG. 1. The attachment device 7 of the temperature sensor device 10 can be a clip member, for example, a metallic clip member, that is configured to be clipped to a bracket member that may be positioned at the windshield 5 or a rearview mirror installed in a vehicle, for example. When the clip member 7 is fastened to the bracket member, a reliable and permanent mechanical and thermal contact between the windshield 5 and the temperature sensor device 10 (andvia the thermally conductive pad 6the temperature sensor 4 of the temperature sensor device 10) is achieved.

[0021] The PCB 1 includes electrically and thermally conductive lines, in particular, copper lines, that may be arranged to receive some heat flow from the windshield 5, and the temperature sensor 4 may be arranged in thermal contact with at least some of the conductive lines. When the temperature sensor device 10 is attached to the windshield 5, the conductive lines may provide a thermal conduction of heat radiated by windshield 5 the towards the temperature sensor 4 whereby the accuracy of the temperature measurement can be significantly increased.

[0022] The temperature sensor device 10 can be relatively easily and cost-efficiently produced using one single PCB 1 only on which the temperature sensor 4 is mounted. Particularly, by attaching the thermally conductive pad 6 to the temperature sensor 4 and arranging the thermally conductive pad 6 in direct contact the inner surface of the windshield 5, an easily to realize thermal contact allowing for a long-term reliable temperature measurement procedure is achieved. By the temperature sensor device 10, a low cost defogging control and/or wiper control in an automobile compartment can be realized, for example.

[0023] Another embodiment of an inventive temperature sensor device 20 is illustrated in FIG. 2. The temperature sensor device 20 is very similar to the one shown in FIG. 1. The temperature sensor device 20 comprises a single rigid PCB 21 that is encased in a housing 22. Some circuitry 23 is formed on the PCB 21. The circuitry 23 comprises circuitry elements used for data processing and sensor control.

[0024] A temperature sensor 24, for example, a (NTC) thermistor, is attached to a tab portion 21a of the PCB 21 as shown in FIG. 2. Thereby, the temperature sensor 24 is directly mounted to the PCB 1. For example, the temperature sensor 24 is soldered to the tab portion 21a of the PCB 21. The temperature sensor 24 is connected to a thermally conductive pad 26 that may be made of or comprise a noble metal, for example, gold. The thermally conductive pad 26 provides a thermal contact with the windshield, the temperature of which has to be sensed by the temperature sensor 24.

[0025] A clip member 27 serves for attachment of the temperature sensor device 20 to a windshield of a vehicle. The clip member 27 has clip tabs 27a that are fastened to the housing 22 and may also be fastened to the PCB 21. Particularly, the clip tabs 27a are in thermal contact with the circuitry 23 that is formed on the PCB 21.

[0026] Heat flow of heat generated by the electronic components of the PCB 21 is indicated by the arrows in FIG. 2. It is desirable that heat generated by the electronic components of the circuitry 23 of the PCB 21 does not influence the measurement of the temperature of the windshield by the temperature sensor 24. Therefore, the clip tabs 27a of the clip member 27 are made of a material, for example, a metal material, that allows for conducting the heat generated by the circuitry 23 away from the temperature sensor 24.

[0027] Additionally, some heat barrier may be provided for blocking heat flow towards the temperature sensor 24. In the embodiment shown in FIG. 2, such a barrier comprises openings 29 formed in the PCB 21 that allow for the dissipation of heat generated by the electronic components of the circuitry 23 of the PCB 21. The openings 29 are arranged between at least portions of the circuitry 23 and the temperature sensor 24. Such openings 29 also increase the accuracy of the temperature measurement since the influence of heat generated by the electronic components of the circuitry 23 on the temperature sensing carried out by the temperature sensor 24 can significantly be reduced.

[0028] In an embodiment, a defogging control device or a wiper operation control device for a motor vehicle includes a humidity sensor device for sensing the humidity of the windshield 5, and the temperature sensor device 10, 20 according to one of the above-described embodiments.

[0029] A method of attaching the temperature sensor device 10, 20 to the windshield 5 of a vehicle comprises the steps of:

[0030] providing a bracket member at the windshield 5 or a rearview mirror installed in the vehicle;

[0031] providing the temperature sensor device 10, 20 including the PCB 10 having thermally and electrically conductive lines; and

[0032] fastening the temperature sensor device 10, 20 to the bracket member such that the thermally conductive pad 6 thermally and mechanically directly contacts the windshield 5 at an inner surface of the windshield 5 directed towards a compartment of the vehicle.