Patent Grant
7342547
This application is based on and hereby claims priority to Japanese Application No. 2005-263996 filed on Sep. 12, 2005 in Japan, the contents of which are hereby incorporated by reference.
(1) Field of the Invention
The present invention relates to glass antennas formed on/in glass substrates and manufacturing methods for the same.
(2) Description of the Related Art
Recently, automobiles often have high-frequency GPS (Global Positioning System) antennas and also antennas for receiving satellite radio waves of satellite digital broadcasting. Further, there has been a demand for other types of antennas for use in ETC (Electronic Toll Collection) systems which automatically charge for use of highways or toll roads, and for radio wave beacons in the VICS (Vehicle Information Communication System). As such types of antennas, there has been technology in which window glass of automobiles is used as a substrate, and patch antennas (planner antennas) are constructed.
Here, for the purpose of good reception of GPS signals, which are circular polarization signals, the antenna conductor 120 has an antenna pattern of a spiral shape. The end of the center of the spiral form is connected to a power supplier 130. The size of the antenna pattern is 58 mm×46 mm, and the width of the line is 1 mm, and the interval between the spiral antenna conductor 120 is 5 mm.
The size of the reflection conductor 210 on the window glass 110 is 120 mm×60 mm. The reflection conductor 210 is electrically connected to the earth of a non-illustrated receiver through the following: a leg portion 170, which is formed by metal fittings for attaching an insulation box 150 to the window glass 110; a ground of an amplifier circuit built in the insulation box 150; and an outer conductor of a coaxial cable 180 for transmitting the output of the amplifier circuit to the non-illustrated receiver. Further, an electric supply line is connected from a power supplier 130, which is electrically connected to the input unit of the above amplifier circuit, to a part of the antenna conductor 120 with a conductive material through a hole 220 provided in the window glass 110.
With the above arrangement, in the present automobile high-frequency glass antenna, radio waves radiated from the antenna conductor 120 to the window glass 110 are reflected by the reflection conductor 210 and radiated to the antenna conductor 120 (outside of the automobile), so that antenna gain is increased.
Next,
Further, the following patent document 3 discloses a technique for printing wiring on glass sheets. In the technique, a glass substrate is laid over a metal board which is appropriate as a conductor pattern material. From above the glass substrate, YAG laser light is emitted with a desired image pattern corresponding to a desired conductor pattern. As a result, the metal board is fused by heat or evaporated, and a desired conductor pattern is transferred to the glass substrate by heat. In this manner, a stable conductor pattern which does not come off easily is printed on the glass substrate, without using any chemicals. As an application of this technique, the following patent document 3 discloses the way of printing antenna conductor patterns on the windshields of automobiles for receiving FM broadcasting.
The following patent document 4 is not an art relating to antennas, but it discloses technology (electromagnetic wave-shielding film) for preventing the leakage and the invasion of electromagnetic waves. This electromagnetic wave-shielding film is a laminated film, on whose opposite sides, a metal conductive layer and a two-dimensional line pattern-printed layer are symmetrically laminated with the basic film as the center layer, or is a laminated film in which such films are laminated. All the patterns on the metal conductive layers and on the printed layers are substantially the same, and the patterns overlap one another on the basis film (the metal conductive layer is covered by the printed layer, viewed from the opposite sides of the basic film). This construction provides a film with good electromagnetic wave-shielding characteristics.
[Patent Document 1] Japanese Patent Application Laid-open No. HEI 7-29916
[Patent Document 2] Japanese Patent Application Laid-open No. HEI 6-247746
[Patent Document 3] Japanese Patent Application Laid-open No. HEI 6-104551
[Patent Document 4] Japanese Patent Application Laid-open No. HEI 10-341093
However, if antennas are simply formed on the surface of window glass as in the above patent documents 1 and 2, or using the technology disclosed in the above patent document 3, a problem of lowering of antenna gain because of loss due to the thickness of glass is caused. That is, normal glass sheets have a conductive loss of approximately 0.02, which is comparatively large. Thus, loss increases in frequencies of the UHF band or higher. If antenna (and ground patterns) are provided on the opposite sides of a glass sheet, gain is lowered because of loss of the glass sandwiched therebetween.
Further, when the technology disclosed in the above patent document 4 is applied to form a conductor pattern on a film, thereby providing an antenna, it is only possible to provide linear antenna. Hence, it is extremely difficult to provide high-gain antennas like patch antennas in which reflection boards are utilized.
With the foregoing problems in view, one object of the present invention is to provide high-gain, low-loss glass antennas which utilize glass substrates. Another object of the invention is to provide a method for manufacturing such antennas. In this instance, the applications of the invention are not limited to mobile objects such as vehicles, and the applications include entrance/exit gate systems and security systems.
In order to accomplish the above object, according to the present invention, the present invention is characterized in that the following glass antennas and their manufacturing method are provided.
(1) As a generic feature, there is provided a glass antenna, comprising: a glass substrate; an antenna pattern; and a ground pattern which reflects a radiated wave radiated from the antenna pattern, either or both of the antenna pattern and the ground pattern being buried inside the glass substrate.
(2) As a preferred feature, the antenna pattern is provided on one side of the glass substrate; and the ground pattern is buried inside the glass substrate.
(3) As another preferred feature, the glass substrate is a laminated glass sheet which is made of two glass sheets, a first glass sheet and a second glass sheet, stuck together with an adhesive layer interposed therebetween, and the antenna pattern is provided on a side opposite to an adhesion side of the first glass sheet, and wherein the ground pattern is provided on the adhesion side of the first glass sheet.
(4) As yet another preferred feature, the glass substrate is a laminated glass sheet which is made of two glass sheets, a first glass sheet and a second glass sheet, stuck together with an adhesive layer interposed therebetween, and the antenna pattern is provided on a side opposite to an adhesion side of the first glass sheet, and the ground pattern is provided on the adhesion side of the second glass sheet.
(5) As a further preferred feature, the ground pattern is provided on one side of the glass substrate, and the antenna pattern is buried inside the glass substrate.
(6) As a still further preferred feature, the glass substrate is a laminated glass sheet which is made of two glass sheets, a first glass sheet and a second glass sheet, stuck together with an adhesive layer interposed therebetween, and the ground pattern is provided on a side opposite to an adhesion side of the first glass sheet, and the antenna pattern is provided on the adhesion side of the first glass sheet.
(7) As an even further preferred feature, the antenna pattern and the ground pattern are buried inside the glass substrate oppositely to each other, the antenna pattern and the ground pattern being apart from each other so that a reflection distance with which the radiated radio wave is capable of being reflected is maintained.
(8) As another preferred feature, the glass substrate is a laminated glass sheet which is made of two glass sheet, a first glass sheet and a second glass sheet, stuck together with an adhesive layer therebetween, and the antenna pattern is provided on an adhesion side of the first glass sheet, and the ground pattern is provided on an adhesion side of the second glass sheet.
(9) As another generic feature, there is provided a glass antenna manufacturing method, comprising: forming an antenna pattern on one side of a first glass sheet, and forming a ground pattern on the other side of the first glass sheet, the ground pattern reflecting radiated radio waves of the antenna pattern; sticking one side of the first glass sheet or the other side of the first glass sheet and one side of a second glass sheet together with an adhesive layer interposed therebetween.
(10) As yet another generic feature, there is provided a glass antenna manufacturing method, comprising: forming an antenna pattern on one side of a first glass sheet, and forming a ground pattern on one side of a second glass sheet, the ground pattern reflecting radiated radio waves of the antenna pattern; sticking one side of the first glass sheet or the other side of the first glass sheet and one side of the second glass sheet together with an adhesive layer interposed therebetween.
According to the present invention, it is possible to construct high-gain antennas such as patch antennas in which a reflection board utilizing the thickness of glass is employed. Further, in comparison with antennas in which antenna patterns are arranged on the opposite sides of glass with the same thickness, it is possible to realize antennas lower in loss.
Further, since either of the antenna pattern and the ground pattern is buried inside the glass substrate, it is possible to protect the buried pattern.
Furthermore, when the antenna pattern and the ground pattern are formed on the opposite sides of a single sheet, those patterns can be accurately aligned, so that glass antennas with desired gain can be easily obtained.
Other objects and further features of the present invention will be apparent from the following detailed description when read in conjunction with the accompanying drawings.
For a design reason, antennas are often formed on glass.
Here, these glass antennas are usable both as transmitter antennas and as receiver antennas. Further, in
That is, a glass antenna (single patch antenna) of the present embodiment, as schematically shown in
Here, the thickness of the whole glass substrate 1 is preferably approximately 10 mm. For example, the thickness of the glass sheets 1a and 1b is preferably approximately 5 mm, and the thickness of the intermediate film is preferably 0.76 mm. In this manner, since the glass has a thickness to some degree, it becomes possible to construct a patch antenna with a reflecting board 3 employed therein. The intermediate film (adhesive layer) 3 can be realized by an adhesive film made of e.g., polyvinyl butyral (the same applies in the following embodiments). Further, the antenna pattern 2 and the ground pattern 3 can be formed using a print technique such as silver printing.
A description will made hereinbelow of a manufacturing method for the above-described glass antenna. For example, as a first step, a print agent (silver paste or the like; the same applies in the following description) is applied over one side 1a-2 of the glass sheet 1a using a screen mesh for a ground pattern 3, and drying and firing is performed. Subsequently, as a second step, the print agent is applied over the other side 1a-1 of the same glass sheet 1a using a screen mesh for an antenna pattern 2, and drying and firing are performed. After that, as a third step, the ground pattern printed side 1a-2 of the glass sheet 1a and the glass sheet 1b, on which no printing is performed, are stuck together with an intermediate film 1c therebetween.
As a result, a glass antenna with the above-described construction is manufactured. Here, the first and the second steps can be performed in an inverse order, or the two steps can be carried out as one step utilizing a double-sided simultaneous printing process. This will reduce manufacturing time and costs.
In this manner, the glass substrate 1 is not given in the form of one glass sheet, but in the form of a laminated glass sheet in which two glass sheets 1a and 1b, half in thickness each, are stuck together, and on the opposite sides 1a-1 and 1a-2 of one of the two glass sheets, the antenna pattern 2 and the ground pattern 3, which are conductor patterns, are formed. In consequence, in comparison with a case where conductor patters are formed on opposite sides of a glass substrate made of one glass sheet with the same thickness (for example, approximately 10 mm), a glass portion between the antenna pattern 2 and the ground pattern 3 is reduced (that is dielectric loss is reduced). Therefore, a high-gain antenna like a patch antenna in which a reflection board 3 can be employed utilizing the thickness of the glass is realized with lower loss.
Further, since the present glass antenna has the ground pattern 3 buried inside the glass substrate 1, the ground 3 is protected. Furthermore, since the antenna pattern 2 and the ground pattern 3 are formed on the same glass sheet 1a, the positions of the antenna pattern 2 and the ground pattern 3 are accurately aligned. In consequence, a glass antenna with a desire gain is manufactured in an easy way.
Here, the thickness of the glass sheets 1a and 1b and the intermediate film 1c should not be limited to the above numerical example, and it can be varied as necessary. In addition, the glass sheet 1a and the glass sheet 1b can be the same or different in thickness. To reduce the dielectric loss induced by glass, the distance between the antenna pattern 2 and the ground pattern 3 is preferably as small as possible. Thus, it is preferable that the thickness of the glass sheet 1a, on which the antenna pattern 2 and the ground pattern 3 are formed, be as small as possible in a range in which necessary gain is assured.
In addition, in order to further reduce dielectric loss between the antenna pattern 2 and the ground pattern 3, thereby realizing low loss, the thickness of the portion of the glass sheet 1a sandwiched between the antenna pattern 2 and the ground pattern 3 is preferably made thin, or the portion is preferably removed and replaced with a material with lower loss than the glass sheet 1a such as ceramic, plastic, and crystal glass (or just removed and left as it is).
Further, the positions at which the antenna pattern 2 and ground pattern 3 are formed should not be limited to the positions illustrated in
Now, a description will be made of a manufacturing method for a glass antenna of the present embodiment. For example, as a first step, a print agent is applied over one side 1a-2 of the glass sheet 1a using a screen mesh for a ground pattern 3, and drying and firing are performed. Subsequently, as a second step, a print agent is applied over the other side 1a-1 of the glass sheet 1a utilizing a screen mesh for an antenna pattern 2, and drying and firing are performed. Then, as a third step, the antenna pattern-printed side 1a-1 of the glass board 1a and a glass sheet 1b, on which no printing is performed, are stuck together with an intermediate film 1c interposed therebetween.
These steps make it possible to manufacture a glass antenna with the above-described construction. In the present embodiment, also, the first and the second steps are changeable in order, or they can be concurrently performed as a single step by using a double-sided simultaneous printing process.
With this arrangement, a radiation electric field is concentrated in the radiation direction (the direction which vertically extends from the antenna pattern 2-formed side 1a-1) of the antenna pattern 2. That is, in the present embodiment, the antenna pattern 2 is buried inside the glass substrate 1 with comparatively large (approximately 7) relative permittivity. In comparison with a glass antenna having the construction already described with reference to
Here, a description will be made of a manufacturing method for a glass antenna of the present embodiment. For example, as a first step, a print agent is applied over one side 1a-2 of the glass sheet 1a using a screen mesh for a ground pattern 3, and drying and firing are performed. Subsequently, as a second step, a print agent is applied over the other side 1a-1 of the glass sheet 1a utilizing a screen mesh for an antenna pattern 2, and drying and firing are performed. Then, as a third step, a contact portion of the intermediate film 1c (to which the glass sheets 1a and 1b are stuck), which portion contacts the antenna pattern 2, is removed in accordance with the shape of the antenna pattern 2, and the portion is filled with a low loss material 1d. Then, as a fourth step, the antenna pattern-printed side 1a-1 of the glass board 1a and a glass sheet 1b, on which no printing is performed, are stuck together with an intermediate film 1c, in which the low loss material 1d is filled, interposed therebetween.
As a result, the glass antenna with a construction illustrated in
The antenna structure of the present embodiment further reduces dielectric loss in the radiation direction of the antenna pattern 2, so that a glass antenna with lower loss than that of the second embodiment is realized. In this instance, in the present embodiment, a portion of the intermediate film 1c (the portion corresponding to the antenna pattern 2) is removed. However, it is not always necessary to remove the portion, and the portion is made thinner than its surrounding portions and the thinned part is filled with the above low loss material 1d. This method is also effective in reducing gain loss.
Further, as shown in
In this embodiment, the glass sheets 1a and 1b are preferably half as thick (5 mm) as the glass substrate 1. However, as to the thickness of the intermediate film (adhesive layer) 1c, it needs to have a thickness (for example, 2 mm or 3 mm) to assure the distance adequate for the ground pattern 3 to function as a reflection board. In this case, the intermediate film 1c can be formed by laminating the necessary number of adhesive films (normally, one film has a thickness of approximately 0.76 mm). Further, in the present embodiment, also, the antenna pattern 2 and the ground pattern 3 can be formed by a printing technique such as silver printing.
Now, a description will be made of a manufacturing method for a glass antenna of the present embodiment. For example, as a first step, a print agent is applied over one side 1a-2 of the glass sheet 1a using a screen mesh for a ground pattern 3, and drying and firing are performed. Subsequently, as a second step, a print agent is applied over the other side 1a-1 of the glass sheet 1a utilizing a screen mesh for an antenna pattern 2, and drying and firing are performed. Then, as a third step, a contact portion of the intermediate film 1c (to which the glass sheets 1a and 1b are stuck), which portion contacts the antenna pattern 2, is removed in accordance with the shape of the antenna pattern 2, and the portion is filled with a low loss material 1d.
Next, as a fourth step, a part (or the whole) of the glass sheet 1b at a position corresponding to the antenna pattern 2 is removed, and a low loss material 1e is filled therein. Then, as a fifth step, the side of the glass sheet 1b on which a low loss material 1e is buried and the antenna pattern printed side 1a-1 is stuck together with an intermediate film 3, in which a low loss material 1d is buried, interposed therebetween.
In this manner, the glass antenna with a construction of
With this arrangement, only the intermediate film 1c, which is thinner than the glass sheets 1a and 1b, exists between the antenna pattern 2 and the ground pattern 3. Thus, in comparison with the already described construction, the distance between the antenna pattern 2 and the ground pattern 3 is small, so that the reflection effect by the ground pattern 3 is improved, and gain is also improved.
In the present example, like in the antenna construction already described in the second embodiment, the antenna pattern 2 is formed on the side 1a-2 which comes into contact with the intermediate film 3, and is buried inside the glass substrate 1, so that a radiation field is concentrated in the radiation direction of the antenna pattern 2 (the direction extending vertically from the side 1a-1 which is opposite the side 1a-2 on which the antenna pattern 2 is formed). That is, in this case, also, since the antenna pattern 2 is buried inside the glass substrate 1 having comparatively large relative permittivity (approximately 7), dielectric loss is slightly increased but the directivity of radiated radio waves is a little improved.
Further, since both the antenna pattern 2 and the ground pattern 3, both of which are conductor patterns, are buried inside the glass substrate 1, it is possible to protect both of the conductor patterns 2 and 3.
In this instance, as in the case of the antenna construction already described with reference to
Here, in the present embodiment, also, the low loss material 1e can be used only in the glass sheet 1a. Further, in the antenna constructions of
That is, the antenna construction of
Here, in the present embodiment, as in the case of the first embodiment, the thickness of the glass substrate 1 should preferably be approximately 10 mm. Since the distance between the antenna pattern 2 and the ground pattern 3 is preferably as small as possible, the thickness of the glass sheet 1a should be thinner than the thickness of the glass sheet 1b, on which the ground pattern 3 is formed. In the present embodiment, the intermediate film (adhesive layer) 1c is realized by an adhesive film such as polyvinyl butyral. The antenna pattern 2 and ground pattern 3 are formed by print technology such as silver printing.
A description will be made hereinbelow of a manufacturing method for a glass antenna of the present embodiment. For example, as a first step, a print agent is applied over one side 1a-1 of the glass sheet 1a using a screen mesh for an antenna pattern 2, and drying and firing are performed. Subsequently, as a second step, a print agent is applied over the other side 1b-1 of the glass sheet 1b utilizing a screen mesh for a ground pattern 3, and drying and firing are performed. Then, as a third step, the side 1a-2 of the glass sheet 1a on which no antenna pattern is printed and the ground pattern-printed side 1b-1 of the glass sheet 1b are stuck together with a intermediate film 1c interposed therebetween.
With these steps, a glass antenna with the above-described construction can be manufactured. In the present embodiment, also, the first and the second steps can be exchanged in order, or these steps can be carried out as a single step by using a double-sided simultaneous printing process. According to the present embodiment, as in the case of the first embodiment, in comparison with a case where the conductor patterns are formed on opposite sides of one glass sheet (with a thickness of, e.g, approximately 10 mm), the thickness of the glass between the antenna pattern 2 and the ground pattern 3 is reduced (that is, dielectric loss is reduced). Thus, high-gain antennas such as patch antennas in which reflection boards are usable, utilizing the thickness of the glass can be realized with lower loss than ever. In addition, since the ground pattern 3 is buried inside the glass substrate 1, it is possible to protect the ground pattern 3.
Here, in the present embodiment, also, in order to further reduce the dielectric loss between the antenna pattern 2 and the ground pattern 3, thereby realizing lower loss, the thickness of the portion of the glass sheet 1a and of the intermediate film 1c sandwiched between the antenna pattern 2 and the ground pattern 3 can be made thinner or the portion can be removed. The portion is preferably replaced with a low loss material such as ceramic, plastic, and crystal glass (or is left as it is).
Further, the present invention should by no means be limited to the above-illustrated embodiment, but various changes or modifications may be suggested without departing from the gist of the invention.
As described so far, according to the present invention, it is possible to provide higher-gain and lower-loss antennas formed on glass substrates, in comparison with previous antennas formed on glass substrates. Thus, the present invention is considered to be significantly useful when employed in technology fields in which radio waves are used, such as automobile GPS antennas, entrance/exit gate systems, and security systems.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2005-263996 | Sep 2005 | JP | national |
| Number | Name | Date | Kind |
|---|---|---|---|
| 3818489 | Bobel, II et al. | Jun 1974 | A |
| 4633262 | Traut | Dec 1986 | A |
| 6198447 | Sauer | Mar 2001 | B1 |
| 6313796 | Potin et al. | Nov 2001 | B1 |
| Number | Date | Country |
|---|---|---|
| 3834075 | Apr 1989 | DE |
| 6-104551 | Apr 1994 | JP |
| 6-247746 | Sep 1994 | JP |
| 7-29916 | Jun 1995 | JP |
| 10-341093 | Dec 1998 | JP |
| 11127012 | May 1999 | JP |
| WO 9534921 | Dec 1995 | WO |
| Number | Date | Country | |
|---|---|---|---|
| 20070057848 A1 | Mar 2007 | US |
