Patent Application
20120166023
The present invention relates to a door opening/closing apparatus of the so-called smart-entry type, including a door opening/closing handle provided in a door of a vehicle, a sensor provided in this door handle, a detection circuit configured to detect a change in electrostatic capacitance occurring in the vicinity of the sensor in response to approaching or contacting of a human body portion relative to the door handle and to output a locking or unlocking operation signal, a device for executing locking/unlocking of the door based on the operation signal and a transmission/reception antenna for effecting transmission/reception with a portable unit corresponding to the vehicle. The invention relates also a coating film forming method for use in the above-described door opening/closing apparatus.
In the case of a door opening/closing apparatus disclosed in Patent Document 1 as an example of prior art document information relating to the door opening/closing apparatus of the above-noted type, as a metallic coating for providing metallic lustrous aesthetic property to a cover to be attached to a main body of the door handle, there is effected a spray coating of a coating material containing, as major components thereof, fine metal particles of aluminum or aluminum alloy and acrylic resin. In doing this, care is taken not to form discontinuous portions of the fine metallic particles wherein the particles are present in discontinuous manner. This is done by positively reducing the thickness of the coating film to from 0.1 to 40 μm. The document reports that loss in antenna output due to the metallic coating was restricted as the result of the above arrangement.
However, with the door opening/closing apparatus disclosed in Patent Document 1, it is difficult to control such that the film thickness of the coating film be uniform. Consequently, there would occur uneven distribution of the fine metal particles, thus inviting the risk that the level of change in the electrostatic capacitance due to a touch by a user's hand varies significantly depending on the position of the hand relative to the door handle. Further, in this known coating arrangement, the fine metal particles are distributed in the acrylic resin as the coating film. Hence, it is difficult to obtain good luster performance equivalent or comparable to that of a metal plating.
On the other hand, according to a further door opening/closing apparatus disclosed in Patent Document 2 which is another prior-art document, in an attempt to overcome the above-described problems present in the technique of Patent Document 1 and to ensure reduction in the antenna output loss as well as stability of communication while retaining metallic luster as substantially good as that of plating, a metal thin film is formed by the sputtering technique on the outer surface of the door handle. The metal cited as an example of a target of sputtering in Patent Document 2 is Cr.
However, with the door opening/closing apparatus disclosed in Patent Document 2, while the restriction of antenna output loss was made possible, the apparatus would still tend to suffer an operation error or failure when a user brings his/her hand or the like into vicinity of or contact with the door handle for having a locking or unlocking operation executed. As an example of such operation error, there can be cited an inconvenient phenomenon that in response to approaching of the hand to an unlock sensor of the door handle for unlocking the locked door, the door is unlocked once, but then is locked again immediately thereafter.
Then, in view of the problem proposed by the door opening/closing apparatuses of the above-cited prior art, the object of the present invention is to provide a door opening/closing apparatus with a door handle having an excellent metallic luster, yet hardly suffering an operation error or an operation failure at the time of locking/unlocking operation.
According to the first characterizing feature of a door opening/closing apparatus relating to the present invention, the apparatus comprises:
a door opening/closing handle provided in a door of a vehicle;
a sensor provided in the door handle;
a detection circuit configured to detect a change in electrostatic capacitance occurring in the vicinity of the sensor in response to approaching or contacting of a human body portion relative to the door handle and to output a locking or unlocking operation signal;
a device for executing locking/unlocking of the door based on the operation signal; and
a transmission/reception antenna for effecting transmission/reception with a portable unit corresponding to the vehicle;
wherein the door handle includes an insulating base body, and on a vehicle outer side surface of the base body, there is attached a metal layer comprised of a group of island shaped metal particles that extend along the surface of the base body and that are separated from each other.
With the door opening/closing apparatus having the first characterizing feature of the present invention, the metal layer provided in the door handle is comprised not of a single and continuous metal thin film, but of a group of island shaped metal particles separated from each other. Hence, while a distinguished mirror-face aesthetic property is retained, the surface resistance can be sufficiently high, thus restricting occurrence of capacitance coupling between the sensor and the metal layer. As a result, there is achieved the advantageous effect of change of electrostatic capacitance occurring in the vicinity of the sensor being rendered stable, which in turn restricts occurrence of an operation error or failure.
Moreover, with the door opening/closing apparatus having the first characterizing feature of the present invention, since the metal layer provided in the door handle is comprised of a group of island shaped metal particles separated from each other, even in the event of occurrence, during use, of partial corrosion due to e.g. formation of a surface flaw as deep as reaching the metal layer, the inter-particle gaps between the metal particles effectively prevent the corrosion from reaching the adjacent metal particles. This is another advantage achieved by the above arrangement.
Incidentally, the arrangement of Patent Document 2 failed to solve the problem of operation error or failure associated with the function of the sensor presumably for the following reason. Since the metal layer thereof is formed by sputtering of a thin film of a metal such as Cr which has a high melting point, the metal layer tends to be formed inevitably as a single metal layer which is continuous throughout, such that the metal layer provides only a low surface resistance (estimated value: below 1×102 Ω/square). Hence, at the time of approach or contact of e.g. a user's hand to the door handle, capacitance coupling tends to occur between the lock sensor or unlock sensor and the metal layer.
According to another characterizing feature of the present invention, the metal particle has a thickness ranging from 10 to 200 nm and a surface resistance value of at least 1×106 Ω/square.
The above arrangement ensures mirror-face like distinguished aesthetic property and achieves also further stability in the changing behavior of the electrostatic capacitance occurring in the vicinity of the sensor.
According to a still another characterizing feature of the present invention, the metal layer is formed by vacuum deposition and the metal particles are comprised of a metal element or an alloy having a lower melting point than aluminum.
With use of a metal element or an alloy having a relatively low melting point such as tin, indium or the like as proposed in the above-described arrangement, the resultant metal layer will not be formed as a generally continuous single metal layer which would be formed by the vacuum deposition with using aluminum, chrome or the like having high melting points as its evaporation source; rather, the resultant layer can be formed easily as a group of island shaped metal particles suitable for the stabilization of electrostatic capacitance in the vicinity of the sensor.
According to a still another characterizing feature of the present invention, the inter-particle gaps between the metal particles adjacent each other range from 5 to 200 nm. According to a still another characterizing feature of the present invention, the metal particles have a particle diameter ranging from 10 nm to 20 μm.
With the above-described arrangements, the metal layer as a whole obtains sufficient degree of reflection, yet has a high surface resistance value. Therefore, while the distinguished aesthetic property is retained, the capacitance coupling between the sensor and the metal layer can be restricted in a reliable manner. As a result, there is achieved the advantage of stability in the change of electrostatic capacitance in the vicinity of the sensor, thus restricting occurrence of operation error or failure.
According to a still another characterizing feature of the present invention, an inorganic transparent thin film is formed between the metal layer and a protective coating for protecting the metal layer.
If an inorganic transparent thin film is formed between the metal layer and a protective coating for protecting the metal layer as proposed by the above-described arrangement, even in the event of degradation of the protective coating due to e.g. UV exposure, development of corrosion or discoloration of the metal layer can be effectively restricted by the inorganic transparent thin film which is chemically stable.
According to the characterizing feature of a coating film forming method which also relates to the present invention, the method comprises a coating film forming step for forming a metal layer by vapor deposition on a base body formed of an insulator;
wherein the metal layer is comprised of a metal element or an alloy having a lower melting point than aluminum; and
the coating film forming step provides, on the base body, a metal layer having a thickness of 30 nm or greater and which layer is comprised of a group of island shaped metal particles separated from each other, and the resultant metal layer has a surface resistance value of at least 1×106 (Ω/square).
With the coating film forming method having the above-described arrangement, while the sufficient mirror-face distinguished aesthetic property is retained, the surface resistance can be sufficient high as high as at least 1×106 (Ω/square). Hence, even in its application to the outer surface of a door handle of a smart entry type door opening/closing apparatus, capacitance coupling between the sensor and the metal layer will hardly occurs. As a result, there can be obtained a door opening/closing apparatus in which the change of electrostatic capacitance occurring in the vicinity of the sensor is stable, thus effectively restricting occurrence of an operation error or an operation failure. Further, since the metal layer provided in the door handle is comprised of a group of island shaped metal particles separated from each other, even in the event of occurrence, during use, of partial corrosion due to e.g. formation of a surface flaw as deep as reaching the metal layer, the inter-particle gaps between the metal particles effectively prevent the corrosion from reaching the adjacent metal particles, advantageously.
Modes of embodying the present invention will be described next with reference to the accompanying drawings.
As shown in
As shown in
Further, as shown in
In this embodiment, the transmission antenna 10 is disposed inside the door handle 2, whereas the reception antenna 14 is disposed inside e.g. a pillar or a luggage room. The car-mounted unit A further includes a transmission circuit (not shown) for the transmission antenna 10, a reception circuit (not shown) for the reception antenna 14, a lock/unlock signal circuit (not shown) for the lock sensor 4a and the unlock sensor 4b, and a control ECU connected to a drive circuit for the actuator 8, etc. The portable unit B includes a transmission antenna, a reception antenna and an ECU (not shown).
As shown in
(Construction of Door Handle)
As shown in
The outer member 2a of the door handle 2 includes a base body 20 formed of PBT (polyethylene terephthalate) by the injection molding technique. On a face of this base body which corresponds to the outer side of the vehicle, there is formed a metal layer 22 for providing an aesthetically distinguished mirror-face like appearance.
More particularly, on the face of the outer member 2a corresponding to the outer side of the vehicle, there is provided a three-layered coating film. As shown in
(Structure of Metal Layer)
As shown in
On the other hand, in spite of such sufficient reflection index as above, this metal layer 22 has a high surface resistance value (as measured prior to the formation of the protective layer) as high as 1×1012˜3×1012 (Ω/square). As a result, there is obtained a door opening/closing door handle 2 that has a distinguished aesthetic property as good as that of the standard chrome plating and whose metal layer 22 hardly provides any adverse effect to the functions of the lock sensor 4a, the unlock sensor 4b, the transmission antenna 10, etc. relating to the electromagnetic wave, the electrostatic capacitance thereof, etc. In particular, the above arrangement effectively restricts a phenomenon of unwanted capacitance coupling between the lock sensor 4a or the unlock sensor 4b and the metal layer 22. Hence, there is obtained a door handle 2 which hardly causes an operation error or an operation failure in the locking or unlocking operation attempted by the user who causes his/her hand to approach or contact to the door handle 2.
The reason for the high surface resistance value of the metal layer 22 is that this metal layer 22 as a whole is comprised not of a continuous coating film, but of a group of island shaped tin particles independent of and separated from each other as illustrated in
(Coating Film Forming Conditions of Metal Layer)
The metal layer 22 is formed by the vacuum deposition technique as an example of the art of thin film coating. More particularly, the layer is formed under the following film forming conditions presented as a non-limiting example.
vacuum degree: 2×10−2 Pa or lower
electric current value: 120 mA
film forming rate: 0.9˜1.2 nm/sec
evaporation source-base body distance: 500˜800 mm (the base body is disposed immediate above the evaporation source, with the deposition-target face thereof oriented downwards)
Under the above-described film forming conditions, on the base body, there was formed an appropriate metal layer having a thickness ranging from 30 to 50 nm by a continuous film forming process for from about 30 to 60 seconds. Incidentally, if the film forming period is too long, the respective tin particles will be extended in a convex manner, thus impairing the flatness, so that there tends to occur such problem as the light reflection index becoming insufficient.
As the metal element or alloy used for obtaining the metal layer 22 by the vacuum deposition technique, one having a lower melting point than aluminum is suitable. Tin which has been confirmed as one example of optimum metal in this invention has a melting point of 232□. If the vapor deposition is effected with using aluminum (melting point: 660□) as the evaporation source, the resultant layer will not be formed as a group of islets-lie particles and high surface resistance value will not be obtained. This applies also chrome (melting point: 1890□).
As examples of such metal elements or alloys having lower melting points than aluminum, there can be cited magnesium (melting point: 651□), indium (melting point: about 157□), tin/bismuth alloy, etc. And, in the case of using one of these as the evaporation source too, there can be obtained a group of island shaped particles and sufficient high surface resistance values.
From the photos of
Incidentally, the SEM photo on the lower side of
From
Incidentally, the respective surface resistance values described above were determined from the metal layers prior to addition of the protective layer (second layer) thereto, by the measurement method according to JIS-K6911 with using a double-ring electrode type resistance meter (Mitsubishi Chemical Analytech Co., Ltd.: Hiresta-UP MCP-HT450).
Example 2 will be described with reference to
In
<1> As the method of forming the metal layer 22 and the inorganic transparent thin film, it is possible to employ any other vapor deposition method than the vacuum deposition method, that is, ion sputtering, ion plating, or any other thin film forming method e.g. CVD.
<2> The material forming the base body 20 is not limited to PBT. Instead, various resins such as PC (polycarbonate) can also be employed.
<3> The first layer and the third layer of the coating film provided on the base body 20 can range from 10 to 40 μm. And, their materials are not limited to the acrylic urethane based coating material, but can be various kinds of coating material such as acrylic coating material, UV curing coating material, etc.
The invention can be applied to a smart entry type door opening/closing apparatus for a vehicle with a door handle having an excellent metallic luster, yet hardly suffering an operation error or an operation failure at the time of locking/unlocking operation.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2009-222389 | Sep 2009 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2010/065619 | 9/10/2010 | WO | 00 | 3/2/2012 |
