JP2010166471A - Antenna - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an antenna, packaged in various mobile communication devices for use, which improves radiation characteristics and is low in price. <P>SOLUTION: The antenna includes an antenna element part by printing a lower conductor layer 2 and an upper conductor layer 16, which overlaps the lower conductor layer 2, on a base sheet 1 using conductive paste in accordance with screen printing. In that case, in a portion that becomes a high frequency band antenna element part, an outer frame 17 overlaps a rectangular part 3 and that portion includes positions at which thickness is partially different. In such a configuration, the usage of conductive paste can be reduced without damaging radiation characteristics and the antenna can configured at low cost. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an antenna that is mounted and used in various wireless devices, mobile communication devices, and the like.

  In recent years, various wireless devices and mobile communication devices have become widespread, and various types of antennas for transmitting and receiving radio waves have been adopted. For example, as an antenna used to receive radio waves for televisions, radios, car navigation systems, etc., film antennas that are used by being attached to automobile window glass or the like have been increasingly used. In addition, as an antenna for transmitting or receiving radio waves of various wireless devices and mobile communication devices, film antennas that are excellent in weight reduction and the like are often used inside devices. Here, the film antenna has a form in which a conductor layer is formed in a predetermined pattern on a base sheet made of an insulating film, and a part of the conductor layer is formed in an antenna element portion.

  There are various methods for forming the conductor layer in a predetermined pattern. For example, a conductive paste having a desired pattern is obtained by printing a conductive paste on a substrate sheet with a screen printer, drying, and curing. There is a method of forming in the element portion. As the conductive paste, silver paste is mainly used.

  As another method, a copper layer is bonded on a base sheet with an adhesive to form a planar copper layer, and then a part of the copper foil is dissolved by etching to form a conductor layer in a desired pattern A subtractive method or the like is also used. This subtractive method using etching requires resist coating, exposure, development, and etching steps, and therefore has a large number of steps and expensive materials, resulting in a problem that the product becomes expensive.

  In contrast, the former method of patterning a conductor layer by screen printing using a conductive paste requires fewer steps and can produce a conductor layer with a desired pattern on a base sheet at low cost. . However, since the conductive paste (silver paste) contains a resin binder, filler, etc., when using this method, sufficient conductivity is obtained, and the conductive material is reduced so that the electric resistance value is also reduced. It is customary to increase the amount. In this way, even in a film antenna made of a conductive paste, conductor loss in the high frequency band can be suppressed, and the antenna radiation characteristics can be improved. Furthermore, in order to improve the radiation characteristics of the antenna, it is often performed to increase the thickness of the conductor layer to lower the electric resistance value of the conductor layer.

  A conventional film antenna formed by printing a conductor layer in a desired pattern shape using such a conductive paste will be described below with reference to FIGS.

  5 is an external perspective view of a conventional antenna, FIG. 6 is an exploded perspective view thereof, and FIG. 7 is an external perspective view showing a state in which the antenna is attached to a substantially rectangular parallelepiped resin base.

  In the figure, reference numeral 1 denotes a base material sheet made of an insulating material having flexibility. As the base sheet 1, various plastic sheets and films can be used, but those having heat resistance capable of withstanding the curing temperature when forming a conductor layer in a desired pattern with a conductive paste are desirable.

  Reference numeral 2 denotes a lower conductor layer printed and formed on the base sheet 1 with a conductive paste. The pattern shape of the lower conductor layer is a rectangular portion formed by solid coating on a substantially rectangular shape serving as an antenna element portion for a high frequency band. 3. A pattern including a belt-like portion 4 which extends from the rectangular portion 3 and surrounds the periphery of the rectangular portion 3 and serves as an antenna element portion for a low frequency band, a feeding portion protruding portion 5, and a grounding portion protruding portion 6. It is formed with. The lower conductor layer 2 is formed by printing a conductive paste in which silver powder is a conductive material and metal particles are dispersed in a resin binder on the base sheet 1 by a screen printing method. The lower conductor layer 2 is formed with a uniform thickness as a whole.

  Further, reference numeral 7 denotes an upper conductor layer that is printed directly on the lower conductor layer 2. The upper conductor layer 7 is formed in the same pattern shape as the lower conductor layer 2. That is, a rectangular portion 8 having the same shape is stacked on the rectangular portion 3 of the lower conductor layer 2, and a strip-shaped portion 9 having the same shape is stacked on the strip 4. Similarly, the power supply protrusion 10 having the same shape is stacked on the power supply protrusion 5, and the grounding protrusion 11 having the same shape is stacked on the grounding protrusion 6. ing. The upper conductor layer 7 is also printed and formed in the pattern shape by the screen printing method using the same conductive paste as the lower conductor layer 2. The reason why the upper conductor layer 7 is formed so as to overlap is that, as described above, it is easy to obtain a sufficient conductivity by increasing the conductor thickness.

  Then, the component parts of the stacked rectangular portions 3 and 8 serve as a first antenna element unit corresponding to the high frequency band, and the component parts of the stacked strips 4 and 9 correspond to the low frequency band. It is an element part. Then, the upper surface positions of the power feeding portion projections 5 and 10 formed in a stacked manner are power feeding portion locations, and the upper surface positions of the grounding portion projection portions 6 and 11 are grounding portion locations.

  As described above, the conventional film antenna is configured, and usually has a form in which the upper surface side excluding the portions to be the power feeding portion and the grounding portion is covered with the protective layer. The protective layer is disposed in order to provide corrosion resistance, insulation, and the like of each antenna element portion. For example, the surface of each antenna element portion is covered with a resist or the like. Examples of the resist ink include inks such as ultraviolet curable resins and thermosetting resins, and the coating method can be performed by means such as printing and coating. Note that the protective layer may be provided on almost the entire surface of the base sheet 1 except for the feeding portion and the grounding portion, or may be formed so as to be slightly wider than each antenna element portion. However, the power feeding portion and the grounding portion described above are not covered with a protective layer in order to become an electrical connection portion with the device used, and the radio, television, navigation system, wireless device, mobile phone, etc. It was set as the structure used as a connection location with the transmission / reception apparatus.

  Furthermore, the adhesive layer 13 is often formed on the lower surface of the base sheet 1. In that case, as shown in FIG. 6, the adhesive surface is covered with the release sheet 14. In addition, the said adhesion layer 13 may be formed in the surface side in which each conductor layer 2 and 7 of the base material sheet 1 is formed. Examples of the material used for the adhesive layer 13 include urethane resin, acrylic resin, polyester resin, and rubber-based resin. And as the peeling sheet 14 provided in order to protect the adhesion layer 13, resin films with high smoothness, such as a polyethylene terephthalate film and a polypropylene film, or what peeled to it is used, for example.

  The conventional film antenna having the above structure is attached by being attached to a resin substrate 15 formed in a substantially rectangular parallelepiped shape, for example, as shown in FIG. At this time, the film antenna can be mounted while being bent at a predetermined location, and after installation, the film antenna is mounted by connecting a radio wave transmission / reception circuit on the device side to the power supply location and the ground location, and the corresponding high frequency band. The first antenna element unit functions during transmission / reception of radio waves, and the second antenna element unit functions and operates in transmission / reception of corresponding low frequency band radio waves.

As prior art document information related to the invention of this application, for example, Patent Document 1 and Patent Document 2 are known.
JP 2001-156522 A JP 2007-267185 A

  However, since the above-described conventional antenna has a configuration in which the upper conductor layer 7 is printed in the same shape on the lower conductor layer 2 in order to ensure desired electrical characteristics, the conductive paste ( There is a problem that the amount of silver paste) used is large, which causes a cost increase.

  The present invention solves such a conventional problem, and an object thereof is to provide an antenna that can be configured at a lower cost than a conventional product and has excellent radiation characteristics.

  In order to achieve the above object, the present invention has the following configuration.

  According to the first aspect of the present invention, a conductor layer is formed in a predetermined pattern on a base material made of an insulating material, and a part of the conductor layer serves as an antenna element part. Is an antenna characterized in that it has portions with partially different thicknesses.

  If it is the said structure, the usage-amount of the electrically conductive paste at the time of carrying out the printing formation of the conductor layer can be reduced, and although it mentions later for details, in the conventional product which formed the antenna element part by the uniform thickness on the whole In contrast, the radiation characteristics of the antenna can be made substantially the same. That is, it has the effect that an inexpensive antenna with excellent performance can be provided.

  The invention according to claim 2 is the invention according to claim 1, wherein the outer peripheral position of the antenna element portion is formed at a thick portion, and the high frequency tends to concentrate on the conductor edge portion. By setting the conductor film thickness at the outer peripheral portion where the height is increased to be partially thick, the conductor loss can be reduced and the radiation characteristic can be improved.

  According to a third aspect of the invention, in the first aspect of the invention, a plurality of antenna element portions are formed by the conductor layer, and the antenna element portion side corresponding to a high frequency has a thin portion having a partially different thickness. Since the antenna element portion corresponding to the high frequency side is generally formed in a large area, the amount of the conductive paste used when the element portion side is configured as described above. This has the effect that the reduction rate can be increased.

  According to a fourth aspect of the present invention, in the first aspect of the present invention, the conductor layer constituting the antenna element portion is further provided with a portion to be a power feeding portion and a ground portion, and a path portion from the antenna element portion or The thickness of the power supply portion and the portion that becomes the grounding portion is formed with at least the same thickness as the thick portion of the antenna element portion, including the power supply portion and the grounding portion and the path portion up to that point. It has an effect that a conductor having good characteristics in which the conductor loss is reduced as a whole can be obtained.

  As described above, according to the present invention, an advantageous effect that an inexpensive antenna having excellent performance can be provided.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. In addition, the same code | symbol is attached | subjected to the part of the structure same as the structure demonstrated in the term of the prior art, and detailed description is abbreviate | omitted.

(Embodiment)
1 is an external perspective view of an antenna according to an embodiment of the present invention, FIG. 2 is an exploded perspective view thereof, and FIG. 3 is an external perspective view showing a state in which the antenna is attached to a substantially rectangular parallelepiped resin base.

  In the figure, reference numeral 1 denotes a base material sheet made of an insulating material having flexibility, and a lower conductor layer 2 is printed and formed on the upper surface thereof with a conductive paste in the same pattern as in the prior art. On the lower conductor layer 2, the upper conductor layer 16 is printed and formed with the same conductive paste.

  Here, the pattern shape of the upper conductor layer 16 is different from the conventional one. That is, the upper conductor layer 16 portion formed by laminating on the rectangular portion 3 of the lower conductor layer 2 having a substantially rectangular shape is formed in the shape of the frame-shaped outer frame portion 17. The outer shape of the outer frame portion 17 is the same as the outer shape of the rectangular portion 3, and the upper surface of the central portion of the rectangular portion 3 is exposed in the outer frame portion 17. The other portions of the upper conductor layer 16 are the same as in the conventional case. That is, a pattern in which the belt-like portion 18, the feeding portion projecting portion 19, and the grounding portion projecting portion 20 are stacked on the belt-like portion 4, the feeding portion projecting portion 5, and the grounding portion projecting portion 6. It has a shape.

  And in the thing of the said structure, the part of the laminated | stacked square part 3 and the outer frame part 17 becomes a 1st antenna element part corresponding to a high frequency band, and the laminated | stacked strip | belt-shaped parts 4 and 18 part are low frequency bands. It becomes the structure which becomes a 2nd antenna element part corresponding to. Further, the upper surface side of the stacked feeding portion projections 5 and 19 is a feeding portion, and the upper surface side of the grounding projections 6 and 20 is a grounding portion.

  Furthermore, an adhesive layer 13 is formed on the entire lower surface of the base sheet 1, and the adhesive surface is covered with a release sheet 14 (see FIG. 2). In addition, it is good also as a form which provided the adhesion layer 13 in the upper surface side of the base material sheet 1, and covered the adhesion surface with the peeling sheet 14. FIG. Moreover, you may make it the form which covered at least each antenna element part except the said electric power feeding part location and the grounding location location with the protective layer.

  The film antenna according to the present invention configured as described above is attached to the resin substrate 15 while being bent with respect to the resin base 15 as shown in FIG. The device side radio wave transmission / reception circuit is connected to the power feeding part location and the grounding location, and the first antenna element unit functions and responds when transmitting / receiving radio waves in the corresponding high frequency band. The second antenna element unit functions when transmitting / receiving radio waves in the low frequency band.

  As described above, the film antenna according to the present invention has a configuration in which the first antenna element portion corresponding to the high frequency band has a portion having a partially different thickness, and the outer peripheral position thereof is formed in a thick portion. Next, the reason for the above configuration will be described.

  When radio waves are transmitted / received via the antenna element portion, the conductor film thickness required differs depending on the frequency band to be used in consideration of the high-frequency skin effect. Further, since a high frequency generates a standing wave due to resonance, a portion having a high current density (current antinode) and a portion having a low current density (current node) are distributed in the conductor pattern. For this reason, the conductor loss can be reduced by setting the film thickness of the portion where the current density is high. Since the high frequency tends to concentrate on the conductor edge portion, it is preferable to increase the film thickness of the edge portion. From the above viewpoint, the outer frame portion 17 is laminated on the rectangular portion 3 with respect to the first antenna element portion corresponding to the high frequency band. In general, the first antenna element portion corresponding to a high frequency is often formed wide in area. Therefore, when the first antenna element portion side is configured as described above, the amount of conductive paste used is There is also an advantage that the reduction rate can be increased. Furthermore, the thickness of the portion that becomes the power feeding portion and the grounding portion and the portion that is connected from each antenna element portion to them is also the same as the thickness of the thick portion of the first antenna element portion or the second antenna element portion having the same thickness. On the other hand, if it is configured to have a thickness that is at least approximately equal, it is possible to reduce the above-mentioned conductor loss as a whole, including the feeding portion, the grounding portion, and the route portion up to that point. Characteristic ones can be obtained.

  Next, the manufacturing process of the film antenna according to the present invention and the result of the characteristic evaluation of the film antenna manufactured by the manufacturing process will be described.

  First, a plastic film (material: polyethylene terephthalate resin, thickness: 25 μm) is used as the base sheet 1, and a conductive paste (components: silver powder, polyester resin, solvent (butyl cellosolve acetate, isophorone) is applied to the upper surface of the screen printing machine. The lower conductor layer 2 was produced through the process of drying and curing, and the formation pattern of the lower conductor layer 2 was a rectangular portion 3 made of a rectangular solid for high frequency band as described above, A pattern having a band 4 for a low frequency band, a power supply protrusion 5 and a grounding protrusion 6 integrally formed around the rectangular portion 3. The drying and curing are performed. The latter thickness is a uniform thickness of 15 μm.

  Next, the upper conductor layer 16 was formed on the lower conductor layer 2 by screen printing using the same conductive paste. As the upper conductor layer 16, an outer frame portion 17 laminated on the rectangular portion 3, a belt-like portion 18 laminated in the same shape on the belt-like portion 4, and a power feed laminated in the same shape on the power feeding portion protruding portion 5. It is assumed to have a pattern shape integrally including a grounding part projecting part 20 and a grounding part projecting part 20 laminated in the same shape on the grounding part projecting part 6. Here, the thickness of the thick film portion in which the upper and lower two layers overlap after drying and curing is 30 μm.

  Next, a resist ink (component: polyester) is applied to the upper surface position of the upper conductor layer 16 excluding the power supply protrusion 19 and the grounding protrusion 20 using a screen printer for the purpose of corrosion resistance and insulation. A protective layer (thickness 15 μm after drying and curing) was formed by printing.

  Furthermore, an adhesive (component: acrylic resin) is printed on the lower surface side of the base sheet 1 using a screen printer to form an adhesive layer 13 having a thickness of 15 μm after drying and curing. A release sheet 14 (material: made of polyethylene terephthalate film, silicone-treated on one side, thickness 38 μm) was attached to the adhesive surface.

  Then, in the film antenna manufactured as described above, the release sheet 14 is peeled off, and the adhesive layer 13 exposed is bent and attached to a substantially rectangular parallelepiped resin base 15 (material: ABS), and is mounted on a mobile phone. The radiation efficiency of the antenna was evaluated in each frequency band (GSM band, DCS band, W-CDMA band) used for mobile phones. A conventional product was also prepared for comparison, and the measurement was also performed. The measurement results are shown in FIGS. 4 (a) and 4 (b). 4 (a) shows the characteristic results in the low frequency band, and FIG. 4 (b) shows the characteristic results in the high frequency band. In both cases, the horizontal axis represents frequency and the vertical axis represents radiation efficiency. The average value of 10 radiation efficiency measurement results is indicated by a white circle, and the average value of 10 radiation efficiency measurement results of a conventional product is indicated by a white square. As shown in FIG. 4, the radiation efficiency of the film antenna according to the present invention was almost the same as that of the conventional film antenna. That is, the product of the present invention has a configuration in which the outer frame portion 17 is changed from the conventional product, but this configuration can maintain the characteristics without losing the radiation characteristics of the antenna, and the amount of conductive paste used can be reduced. It was found that it can be reduced. In addition, as the reduction amount, in the case of the above-described configuration and process, it was possible to reduce the usage amount of the conductive paste by about 1/4. In addition, the cost can be significantly reduced even when compared with the one manufactured by the etching method described in the conventional section.

  As described above, according to the present invention, the usage amount of the conductive paste can be reduced without impairing the radiation characteristics of the antenna, and an inexpensive antenna with excellent performance can be provided.

  The idea according to the present invention described above can be applied to all antennas that form an antenna element portion by printing a conductive paste. In the above description, an example of a two-layer conductor structure that overlaps the upper and lower sides and an element having a portion with a partially different thickness only in the antenna element portion for the high frequency band has been described. The same effect can be obtained even if the idea is applied to an antenna element portion or the like. Further, the number of conductor layers to be laminated is not limited to only two upper and lower layers, and only the upper conductor layer may be provided using a printing method. Further, the conductive paste may have other conductive powders other than silver powder.

  And although the structure which used the base material sheet 1 was demonstrated above, the thing made from a hard insulating material etc. may be used as a base material. Moreover, you may comprise the antenna element part which has a location from which thickness differs partially using methods other than a printing method.

  The antenna according to the present invention has a feature that it can provide an inexpensive and excellent characteristic without impairing radiation characteristics, and is useful as an antenna for various wireless devices including mobile devices and mobile communication devices. .

1 is an external perspective view of an antenna according to an embodiment of the present invention. Exploded perspective view External perspective view showing a state where the antenna is attached to a substantially rectangular parallelepiped resin base The figure which shows the characteristic result of the radiation efficiency External perspective view of a conventional antenna Exploded perspective view External perspective view showing a state where the antenna is attached to a substantially rectangular parallelepiped resin base

DESCRIPTION OF SYMBOLS 1 Base material sheet 2 Lower conductor layer 3 Rectangular part 4, 18 Band-like part 5, 19 Feed part protrusion part 6, 20 Ground part protrusion part 13 Adhesive layer 14 Release sheet 15 Resin substrate 16 Upper conductor layer 17 Outer frame part

Claims (4)

A conductor layer is formed in a predetermined pattern on a base material made of an insulating material, and a part of the conductor layer serves as an antenna element part, and the antenna element part has a part with a partially different thickness. An antenna characterized by being made. The antenna according to claim 1, wherein the outer peripheral position of the antenna element portion is formed at a thick portion. The antenna according to claim 1, wherein a plurality of antenna element portions are formed of a conductor layer, and the antenna element portion side corresponding to a high frequency has a thin portion partially having a different thickness. The conductor layer constituting the antenna element portion is further provided with a portion serving as a feeding portion and a ground portion, and the thickness of the route portion from the antenna element portion and the portion serving as the feeding portion and the ground portion is determined as the antenna element portion. The antenna according to claim 1, wherein the antenna is formed to have at least an equivalent thickness with respect to a thick portion.

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