FIELD

The present disclosure relates to an automotive mirror, and more specifically, to a heatable vehicle mirror using a silver conductive paste. It also relates to a vehicle with at least one such heatable vehicle mirror.

BACKGROUND

The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.

When a vehicle is travelling in rainy or snowy weather, the outside mirrors collect water droplets or ice, degrading the rearward view and therefore lowering the safety of driving. To improve driving safety, various types of mirrors surfaces exist which can be heated to remove water droplets and ice adhering to the mirror surface. These mirrors in general use a thermal detection unit to detect the temperature of the mirror and may control the heating parameters of the mirror. Using a thermal detection unit causes additional complexity issues in packaging and manufacturing as well as increasing the cost of the mirror unit.

Current heatable mirrors for a vehicle are not effective at providing an even distribution of the heat across the mirror surface. Some areas are heated to a higher temperature than a nearby area. This can create a mirror viewing area which is not completely cleared causing it to be more difficult to view images in the mirror glass. An uneven heat distribution can also cause difficulties for other nearby components which may be temperature sensitive and may cause concerns with personal safety to touch the surface. The current heatable vehicle mirrors usually comprise heater means with a positive temperature coefficient (PTC) material for controlling the thermal mechanism of a mirror as well as a thermal detection unit for temperature detection of the mirror. The addition of the heater means with PTC leads to an increase of costs of the mirrors. Another concern with known heatable vehicle mirrors is the geometry of the mirror surface. Typically the heatable mirrors are planar which improves the effectiveness and manufacturability of the heated mirror module. However, a planar mirror does not provide an optimal viewing area for the driver. Curved mirror geometries provide a wider viewing area decreasing blind spots for the driver.

It is the object of the present disclosure to provide a heatable vehicle mirror overcoming at least some of the drawbacks of the prior art.

SUMMARY

The object of the present disclosure is solved by claim 1. The sub-claims 2 to 10 describe embodiments of heatable vehicle mirrors according to the present disclosure. Claim 11 refers to a vehicle with a heatable vehicle mirror.

It should be noted that the features set out individually in the following description can be combined with each other in any technically advantageous manner and set out other forms of the present disclosure. The description further characterizes and specifies the present disclosure in particular in connection with the Figures.

An aspect of the present disclosure is to provide improved thermal performance with an efficient way for evenly spreading temperature across a mirror plate for a heatable vehicle mirror. According to the present disclosure, the heatable vehicle mirror has a mirror plate, and a chrome film is applied to the back of the mirror plate with a first outer edge and a second outer edge. At least two separate silver paste areas are applied to the chrome film in a first area adjacent to the first outer edge and in a second area adjacent to the second outer edge of the chrome film. At least two electrode terminals are electrically coupled to the chrome film and the at least two silver paste areas. Another aspect of the present disclosure further defines the first area to have a first inner edge located inward of the first outer edge and the second area to have a second inner edge located inward of the second outer edge. A distance may be measured from a point on the first inner edge to a corresponding point on the second inner edge. This distance may be measured from a first point along the first edge to a corresponding second point on the second edge and will be substantially equidistance for any selected first point along the length of the first inner edge measured to a corresponding second point along the length of the second inner edge. This equidistance maintains a uniform distance for the exposed chrome film with no applied silver paste on the mirror plate. The first area of silver paste may have a first shape and the second area of silver paste may have a second shape and the at least two silver paste areas may be printed on the chrome film preferably using serigraphy.

According to a further aspect of the present disclosure, the heating performance of the heatable vehicle mirror may be achieved utilizing a thickness of the chrome film in the range of 35 ~ 50 /Zin with a resistance between 5 ~ 8Q. The conductive silver paste areas may have a thickness in the range of 100-200 jt/m with a resistance of the conductive silver paste under 0.1 .

According to a further aspect of the present disclosure, the temperature equilibrium condition for improved thermal performance heating mirror plate may be achieved in less than or equal to 600 seconds at a temperature range between 75°C and 85°C.

In another aspect of the present disclosure, the heatable vehicle mirror maycomprise a backing plate which has at least two attached electrode terminals. The at least two electrode terminals may be electrically coupled to the reflective heating resistor chrome film and directly coupled to the at least two silver paste areas. The electrode terminal may be connected to a power supply to activate the resistance of the reflective heating resistor chrome film providing heat to the mirror plate.

It should be noted that the features set out individually in the following description can be combined with each other in any technically advantageous manner and set out other forms of the present disclosure. It should be understood, however, that the disclosure is not limited to the precise arrangements and instrumentalities shown. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate an implementation of system, apparatuses, and methods consistent with the present description and, together with the description, serve to explain advantages and principles consistent with the disclosure. The figures are not necessarily drawn to scale. Like numbers used in the figures refer to like components. However, it will be understood that the use of a number to refer to a component in a given figure is not intended to limit the component in another figure labelled with the same number. The description further characterizes and specifies the present disclosure in particular in connection with the figures.

DRAWINGS

In order that the disclosure may be well understood, there will now be described various forms thereof, given by way of example, reference being made to the accompanying drawings, in which:

Fig. 1 illustrates a layer structure of a heatable vehicle mirror,

Fig. 2a illustrates a back view of a heatable vehicle mirror with a first pattern,

Fig. 2b illustrates a back view of a heatable vehicle mirror with a second pattern ,

Fig. 3a illustrates an exploded view of the heating system components of a heatable vehicle mirror,

Fig. 3b illustrateselectrode terminals of the heatable vehicle mirror,

Fig. 4a illustrates a rear perspective view of a backing plate with connection with the electrode terminals of the heatable vehicle mirror,

Fig. 4b illustrates an enlarged area of the backing plate connection with the electrode terminals of the heatable vehicle mirror,

Fig. 4c illustrates a section along line A in Fig. 4a of the backing plate connection with the electrode terminal of the heatable vehicle mirror, Fig. 5 illustrates an exemplary graphical representation of thermal equilibrium condition of the heatable vehicle mirror, and

Fig. 6 illustrates an exemplary temperature spread of the heatable vehicle mirror.

DETAILED DESCRIPTION

The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features.

This disclosure refers to heating a mirror surface using conductive silver paste applied in a specific pattern for controlling the temperature of the mirror surface without using an additional heater means with PTC material. This eliminates the need of a temperature detection unit in a mirror unit and leads to less part complexity and cost. This disclosure provides for improved thermal performance and may also be utilized for curvature type mirrors.

FIG. 1 illustrates layer structure of a heatable vehicle mirror 10. The heatable vehicle mirror 10 comprises a mirror plate 100, a chrome film 102 and a conductive silver paste 104. The heatable vehicle mirror 10 structure shown in Fig. 1 may have a curvature such as an elliptical curvature or may be planar. The mirror plate 100 in this form is a mirror glass plate. The reflective chrome film 102 is affixed to the mirror plate 100 and is able to provide a resistance to be utilized for heating the surface of the mirror plate 100. The thickness of the chrome film 102 is selected based on the resistance of the chrome film 102 to achieve the desired ampere on the mirror plate 100. In this form, the thickness of the chrome film 102 is between 35 - 50 jt/m. The silver paste 104 is a conductive silver paste 104 applied in a pattern as described with respect to Fig. 2a and 2b to the surface of the chrome film 102. In this form, the silver paste 104 is printed over the chrome film 102, more specifically printed by serigraphy with a thickness is between 100-200 jt/m . In other variations, the silver paste 104 may be applied in other ways to the chrome film 102. The conductive silver paste 104 is applied on an outer edge of the chrome film 102 (Fig. 2a and 2b) and is connected with at least two electrode terminals 106. Specifically, at least one terminal of the at least two electrode terminals 106 is positive and at least one of the at least two electrode terminals 106 is negative. The at least two electrode terminals 106 are connected to a power supply (not shown) which may be an independent power supply or a vehicle supplied power supply for about 13.5 Volts. The power supply provides current which is transferred from the at least two electrode terminals 106 through the silver paste 104 to the chrome film 102 which heats the surface of mirror plate by the resistance of the chrome film 102.

FIG. 2a and 2b depict a back view of a first and a second exemplary pattern of the applied silver paste 104 on the chrome film 102 with two separate silver paste areas 104a and 104b, respectively.

Fig. 2a illustrates the first pattern of the applied silver paste 104 as a crescent type pattern. The silver paste 104 is applied with a first silver paste area 104a applied adjacent to a first outer edge 108 of the chrome film 102 and having a first inner edge 112. A second silver paste area 104b is applied adjacent to a second outer edge 110 of the chrome film 102 and having a second inner edge 114. In the exemplary crescent type pattern shown in Fig. 2a, two conductive silver paste areas 104a and 104b are shown but additional areas may be utilized. The geometry parameters for the first silver paste area 104a are different than geometry parameters for the second silver paste area 104b. In other forms, the geometry parameters of the first and second silver paste areas 104a and 104b may be identical.

Fig 2b illustrates the second pattern of the applied silver paste 104 as a finger type pattern. The second pattern has a first silver paste area 104a applied adjacent to the first outer edge 108 and a second silver paste area 104b applied adjacent to the second outer edge 110 of the chrome film 102. As described above in reference to Fig. 2a, the geometry parameters for the finger type pattern for the first silver paste area 104a are different than the printed geometry parameters for the second silver paste area 104b. In other forms, the first and second silver paste areas 104a and 104b may have similar geometry parameters.

As shown in Fig. 2a and Fig. 2b, distance measurements A, B, and C are illustrated in relation to the first and second silver paste areas 104a and 104b. In both the first and the second exemplary patterns (Fig. 2a, 2b), distances A, B, and C are measured between a point on the first inner edge 112 of the first silver paste area 104a and a corresponding point on the second inner edge 114 of the second silver paste area 104b. The distance of the exposed chrome film 102 between the first inner edge 112 and the second inner edge 114 is substantially equidistant along the entire contour of the first and second inner edges. This distance measurements A, B, C along the first and second inner edges 112 and 114 determine the pattern of the first silver paste area 104a in relation to the second silver paste area 104b applied on the chrome film 102. The distance measurements also determine the amount of chrome film 102 which is not covered by the first and second silver paste areas 104a and 104b. By maintaining an equal distance between the first and second inner edges 112 and 114, the amount of exposed chrome film 102 is consistent leading to an improved thermal distribution to the mirror plate 100 (Fig. 1). As shown in Fig. 2a and 2b, the measurement distances A, B and C are substantially equal distant which provides consistent heating of by the resistance of the chrome film 102.

FIG. 3 a illustrates an exploded view of the heating system components for the heatable vehicle mirror 10. A first silver paste area 104a and a second silver paste area 104b are applied to the back side of ta chrome film 102 as described above. At least two electrode terminals 106 are coupled to a non-conductive backing plate 118 best seen in Fig. 4. The backing plate 118 is positioned between the chrome film 102 with applied first and second silver paste areas 104a andl04b and the at least two electrode terminals 106. A mirror housing (not shown) aligns the backing plate 118 such that the at least two electrode terminals 106 are electrically connected to the silver paste 104 as illustrated in Fig. 4.

Fig. 3b illustrates examples of the at least two electrode terminals 106 such as a pogo pin type 106a, a conductive fingers type 106b and a conductive spring type 106c which may be used for in the heating system for the heatable vehicle mirror 10.

Fig. 4a illustrates a rear perspective view of the backing plate 118. In this figure, two electrode terminal areas 120 are used, An enlarged view of such an area 120 is shown in Fig. 4b to illustrate the arrangement of at least one electrode terminal 106, e.g. of the pogo pin type 106a. In this form, the two electrode terminal areas 120 are identical. In other forms, the two electrode terminal areas 120 may have different configurations. Fig. 4a also defines a section line “A” shown for use in Fig. 4c. The mirror plate 100, the chrome film 102 and the silver paste 104 which make up the mirror heating system for the heatable vehicle mirror 10 are illustrated in Fig. 4c but not in the rear view of Fig. 4a.

The pogo pin type 106a is shown in Fig. 4b coupled to the backing plate 118 and is in electrical contact with the silver paste 104. The pogo pin type 106a is shown as inserted or embossed inside the backing plate 118. Fig. 4c illustrates a sectional view defined by the section line A through the backing plate 118 shown in Fig. 4a. Illustrated in this figure, is an exemplary configuration of the layers of the heatable vehicle mirror 10. The electrode terminal 106 of pogo pin type 106a is shown inserted into the backing plate 118. An adhesive 116 is shown to form a bond between the backing plate 118 and the silver paste 104. The pogo pin type 106a electrode terminal 106 is shown in direct and electrical connection with the silver paste 104 and the chrome film 102. In this form the pogo pin type 106a is embedded in the silver paste 104 and the chrome film 102 by between 0.25 and 0.75 mm, preferably the overlap 122 is 0.5 mm. The current will be supplied by the electrode terminal 106 of the pogo pin type 106a to the silver paste 104 and the chrome film 102. The resistance of the chrome film 102 will provide heating for the mirror plate 100. In other forms, the electrode terminal 106 of the pogo pin type 106a may contact the silver paste 104 with an overlap 122 of 0.5mm and not make a direct electrical connection to the chrome film 102. The current will then be transferred from the pogo pin type 106a through the silver paste 104 to the chrome film 102.

Fig. 5 depicts an exemplary graphical representation of a thermal equilibrium condition of the heatable vehicle mirror 10. Even distribution of heat provides improved removal of water and ice from the heatable vehicle mirror 10 and also prevents safety issues with potential higher temperature areas for the user. The thermal equilibrium condition for the heatable vehicle mirror 10 is shown at point 124. The thermal equilibrium may be achieved in the time duration of 600 seconds for a temperature range of 75°C ~ 85°C. The resistance range of the chrome film 102 may be between 5 ~ 8 and the resistance of the conductive silver paste 104 under 0.1 to meet the condition where the mirror plate 100 temperature is in thermal equilibrium condition between 75°C ~ 85°C. Maintaining the resistance of the chrome film 102 between 5 ~ 8 leads to even distribution of temperature over the applied chrome film 102 and results in equalized heating of heatable vehicle mirror 10. Fig. 6 illustrates an exemplary thermal distribution achieved by the mirror plate 100 of the heatable vehicle mirror 10 in this disclosure. In this figure, the exemplary first pattern shown in Fig. 2a is illustrated with the heatable vehicle mirror 10 at equilibrium. The areas illustrated in Fig. 2a, i.e. the first silver paste area 104a and the second silver paste area 104b are shown as shaded in Fig. 6. The portion of the chrome film 102 which is not covered by the silver paste 104 (Fig. 2a) creates an even distribution of thermal temperature over the mirror plate 100 denoted by thelighter area. This thermal distribution shown is in the temperature range of 75°C ~ 85°C and is consistently an even heat distribution across the mirror plate 100 with no hot spots on the mirror plate 100. This leads to improved performance in removing water and ice from the mirror plate 100 and increases the safety of the user and components located nearby. The thermal equilibrium condition of the heatable vehicle mirror 10 is reached in the time duration 600 seconds for the temperature range of 75 °C ~ 85 °C.

The foregoing description of various preferred embodiments have been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the disclosure to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. The example embodiments, as described above, were chosen and described in order to best explain the principles of the disclosure and its practical application to thereby enable others skilled in the art to best utilize the disclosure in various embodiments and with various modifications as are suited to the particular use contemplated.

REFERENCE SIGN LIST

10 - Heatable Vehicle Mirror

100 - Mirror Plate

102 - Chrome Film

104 - Silver Paste

104a - First Silver Paste Area

104b - Second Silver Paste Area

106 - Electrode Terminal

106a - Pogo Pin Type

106b - Conductive Finger Type

106c - Spring Type

108 - First Outer Edge

110 - Second Outer Edge

112 - First Inner Edge

114 - Second Inner Edge

116 - Adhesive

118 - Backing Plate

120 - Electrode Terminal Area

122 - Overlap

124 - Point

A - Section Line