JP2007093629A - Radio wave transmission retroreflection sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a radio wave transmission retroreflection sheet which can be preferably used for an active, passive retaining the visibility in nighttime or a retroreflective RFID device by combination with an RFID. <P>SOLUTION: The radio wave transmission retroreflection sheet is constituted so that in the retroreflection sheet having a mirror surface reflection layer, mirror surface reflection regions having the mirror surface reflection layer are electrically insulated from one another by non-mirror surface reflection regions having no mirror surface reflection layer and form independent regions which are partially disposed with a repeated pattern and, as the result, the radio wave transmission can be exhibited. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to a radio wave transmitting retroreflective sheet. Specifically, in the retroreflective sheet in which the specular reflection layer is installed, the specular reflection area in which the specular reflection layer is installed is electrically insulated from each other by the non-specular reflection area in which the specular reflection layer is not installed, and is an independent area. The present invention relates to a radio wave permeable retroreflective sheet that is installed in a repeating pattern and exhibits radio wave transmissivity.

In more detail, the non-specular reflection region constitutes a region in which linear, bent, and / or curved linear regions having a width of 0.1 to 1.5 mm are connected to each other. Regarding the sheet.

The radio wave transmitting retroreflective sheet in the present invention is a radio frequency authentication device (Radio Frequency
This is called an identification device, hereinafter referred to as an RFID device. ), It can be preferably used for an RFID device that maintains nighttime visibility.

Several proposals have been made regarding retroreflective RFID devices that combine a retroreflective sheet and an RFID device.

Japanese Patent Laid-Open No. 9-508983 (Patent Document 1) by Pantry discloses an integrated retroreflective electronic display device. According to the description of this patent, a retroreflective device for visual and electromagnetic information communication, which is a retroreflective sheet having visual information for retroreflecting incident light, is a single-layer retroreflective micrometer. A retroreflective sheet comprising a base sheet having a sphere group embedded in one surface, and a regular reflection means for light spaced apart from the base sheet via a transparent material, and an electromagnetic An apparatus comprising an antenna means for communication and a coupling means enabling coupling to the antenna means is disclosed.

However, in the description of the retroreflective sheet that can be preferably used in the Pantry invention, for example, “a new type of retroreflective sheet that is not opaque to electromagnetic radiation can be used, and the retroreflective sheet is used as the ground plane of the antenna network. A continuous conductive reflective layer of the sheet can be used ". In addition, “the retroreflective sheet of the encapsulated lens, such as the strong grade of the 3M brand Scotchlite reflective sheet manufactured by Minnesota Mining and Manufacturing Company, can be used as the retroreflective sheet of the electronic license plate 2”. However, it is not disclosed what kind of retroreflective sheet can be preferably used, and only a commercially available retroreflective sheet is used.

Further, Japanese Patent Publication No. 11-505050 (Patent Document 2) by Pantry et al. Discloses an electronic license plate having a safety identification device. According to the description of this patent, an electronic license plate device for use in an electronic vehicle communication device in which a plurality of remote traffic management stations communicate with an electronic license plate, comprising visual identification information and limited information, at least one A license plate including identification means for storing limited information that includes one type of vehicle identification information and cannot be changed by the remote station or vehicle, non-limiting information, at least one remote Information means for storing non-limiting information that can be changed by a station or vehicle, said identification means and communication means operatively connected to said information means for processing communications with said remote station, Antenna means for transmitting / receiving communication contents with the communication station, An electronic license plate apparatus, comprising: mounting means fixed to both and for detachably mounting the license plate portion to a vehicle so as to replace the license plate portion without requiring replacement of information means. It is disclosed.

Further, International Publication WO-02 / 103629 (Patent Document 3) by Mimura describes a recursion characterized by comprising an integrated circuit module incorporating an integrated circuit, a light retroreflective element, and a supporting layer thereof. An invention relating to a reflective integrated circuit encapsulated product is disclosed.

However, it is not disclosed in any invention whether the retroreflective sheet having any structure can be preferably used because it is provided with excellent radio wave transparency and retroreflective properties.

Patent literature
Bantry, special table hei 09-508983 Pantry et al. Mimura, International Publication WO-02 / 103629 Bellisle et al., JP 59-071848 Bellisle et al., U.S. Pat.No. 4,721,649 Bellisle et al., U.S. Pat.No. 4,725,494 McKenzie, Shoko 40-007870 Mackenzie, U.S. Pat.No. 3,190,178 McGrath, JP 52-110592 McGrath, U.S. Pat.No. 4,025,159 Bailey, JP 62-121043 Bailey, U.S. Patent No. 5,064,272 Roland, special table flat 8-510415 Roland, U.S. Pat.No. 5,376,272 Mimura et al., International Publication Gazette WO-01 / 057560 Mimura et al., U.S. Patent No. 6,817,724

The problem to be solved by the present invention is to provide a radio wave-transmitting retroreflective sheet that can be preferably used in an active or passive RFID device that retains night visibility in combination with an RFID device.

Another problem to be solved by the present invention is to supply a retroreflective sheet that is capable of efficiently transmitting weak radio waves in the communication of RFID apparatuses using weak radio waves, and particularly for passive RFID devices. It is in the supply of a radio wave-transmitting retroreflective sheet that can be preferably used.

A further problem of the present invention is a radio wave transmissive retroreflective sheet that can be preferably used for a retroreflective RFID device, and has radio wave transmissive properties with excellent retroreflective properties that can sufficiently ensure nighttime visibility. The supply of retroreflective sheets.

When such a retroreflective RFID device is used for a vehicle license plate, a third plate (vehicle recognition sticker attached to a vehicle glass window), or a traffic sign, it is required to ensure retroreflective performance as a retroreflective device. . The problem to be solved by the present invention is to provide a radio-transmissive retroreflective sheet that can satisfy the requirement of retroreflective performance while ensuring the communication performance of the RFID device.

An object of the retroreflective RFID apparatus according to the present invention is to enable efficient radio wave communication with a RFID reader installed outside via a mutual communication antenna.

The radio wave transmission type retroreflective sheet according to the present invention is a retroreflective sheet in which a specular reflection layer is installed, and the specular reflection region in which the specular reflection layer is installed is electrically connected to each other by a non-specular reflection region in which the specular reflection layer is not installed. It is insulated and partly installed in a repetitive pattern in an independent area, showing radio wave transmission.

As a method of partially installing the specular reflection layer as an independent region, a method of partially removing the specular reflection layer in advance after installing the specular reflection layer in all regions or a method of partially installing the specular reflection layer is adopted. I can do it.

As a partial removal method, a chemical etching method, a mechanical removal method, an energy beam irradiation method, and a chemical reaction method can be employed.

As chemical etching method, etching treatment liquid such as various acids and alkalis that can be removed as a soluble salt by reacting with the specular reflection layer is applied by printing, spraying, etc. to partially remove the specular reflection layer. Is used. After the etching, it is preferable to perform washing with water in order to protect the specular reflection layer from corrosion of the treatment liquid. Further, a thickener for improving printability and sprayability can be added to the treatment liquid. As a printing method, known printing methods such as gravure printing, flexographic printing, screen printing, and ink jet printing can be appropriately employed, but flexographic printing and gravure printing are particularly preferable because a delicate print pattern can be easily obtained.

As a mechanical removal method, the specular reflection layer can be partially removed by a method such as brush polishing or sand blasting after laminating a mask sheet for protecting the non-removed surface.

As the energy irradiation method, a method of vaporizing and removing the specular reflection material by continuously scanning a high energy beam such as a laser beam or an electron beam in the removal region can be employed. Such an energy ray irradiation method can be particularly preferably used because a preferable shape of the non-specular reflection region can be freely or partially formed.

In the retroreflective sheet of the present invention, a laser beam irradiation method can be particularly preferably used. Various laser light sources such as YAG laser and carbon dioxide laser can be used as the laser beam to be irradiated, but the light source is not particularly limited. Further, the diameter of the laser beam can be adjusted as appropriate in accordance with the width of the non-specular reflection region, and in some cases, wider processing can be performed by scanning twice or more.

Laser processing can be performed by irradiating from the front reflective layer side of the retroreflective sheet to remove the specular reflective layer, but irradiating the specular reflective layer directly from the back of the retroreflective sheet before laminating the adhesive layer Is preferred.

As the chemical reaction method, a method of forming a non-conductive oxide, salt or the like by reacting with a specular reflection material to lose conductivity can be employed. As the reactive material, various acids and alkali compounds that react with the specular reflection material can be used.

In addition, as a method of partially installing the specular reflection layer, it is possible to install the specular reflection layer by a method such as vacuum deposition, sputtering, or chemical plating after laminating a mask sheet that protects the non-specular reflection region. I can do it.

The specular reflection area in which the specular reflection layer is installed in the present invention is electrically insulated from each other by a non-specular reflection area in which no specular reflection layer is installed, and is partially installed in a repeating pattern forming an independent area. Has been. If they are not electrically insulated from each other by the non-specular reflection region, the radio wave permeability is lowered, which is not preferable.

The area where such a non-specular reflection area is installed may be installed over the entire retroreflective part of the retroreflective RFID apparatus, but it is partially installed in the area where the RFID antenna apparatus is installed. May be. In such a partial installation method, it is preferable that the non-specular reflection region is installed larger than the area of the antenna device because of excellent radio wave recognition characteristics. Preferably, the outer periphery of the antenna is preferably 10 mm or more in the non-specular reflection region, and more preferably 25 mm or more.

The non-specular reflection region in the present invention constitutes a region in which linear, bent, and / or curved linear regions having a width of 0.1 to 1.5 mm are connected.

If the width of the non-specular reflection region is less than 0.1 mm, it is difficult to maintain the electrical insulation between the specular reflection regions, and this is not preferable because the radio wave transmission is reduced. On the other hand, when the thickness exceeds 1.5 mm, the retroreflective performance is deteriorated, or retroreflected light at night is sparse and the appearance is not uniform. Therefore, the preferable width is 0.1 to 1.5 mm, and more preferably 0.2 to 1.0 mm.

The shape of the non-specular reflection region is a linear region having a linear shape, a bent line shape, and / or a curved shape, and an independent specular reflection region remains depending on the combination of these linear regions.

The shape of the independent region of the specular reflection region in the present invention is such that the aspect ratio (L / S) between the outer end length (L) in the longest direction of the independent region and the outer end length (S) in the direction perpendicular thereto is 2 The above is preferable.

A radio wave transmissive retroreflective sheet with a specular reflection area with such a large aspect ratio is especially suitable for RFID devices or external devices with communication antennas that emit highly directional radio waves such as bar antennas and dipole antennas. Particularly preferred in the case of a reader.

The installation direction of the retroreflective sheet must be changed depending on the installation direction of the reading antenna and the directivity direction of the radio wave. An aspect ratio of less than 2 is not preferable because reading performance deteriorates.

The shape of the reflection region may be a rectangle partitioned by a straight non-specular reflection region. In the case of such a rectangular non-specular reflection region, the aspect ratio is determined by the size of the retroreflective sheet installed in the retroreflective RFID device used. In addition, when the non-specular reflection region is partially installed, the size is determined by the size of the non-specular reflection region.

The area ratio of the independent region of the specular reflection region in the present invention is preferably 85 to 99%.

If it exceeds 99%, it is difficult to maintain the electrical insulation between the specular reflection regions, and this is not preferable because the radio wave transmission is reduced. On the other hand, if it is less than 85%, the retroreflective performance is lowered, or retroreflected light at night is sparse and the appearance is not uniform. Therefore, a preferable area ratio is 85 to 99%, and more preferably 88 to 98%.

An encapsulated lens type retroreflective element, a capsule lens type retroreflective element or a cube corner type retroreflective element can be adopted as the retroreflective element constituting the retroreflective sheet in the present invention.

The retroreflective element that can be used in the present invention and the retroreflective sheet formed by the retroreflective element can be produced by a method known per se and are not particularly limited.

These retroreflective elements are provided with a specular reflection layer, and the incident light can be efficiently specularly reflected.

In addition, the specular reflection layer component constituting the specular reflection layer in the present invention is preferably aluminum, silver, nickel, and / or copper, and particularly preferably aluminum because the appearance of the sheet can be brightened. .

These specular reflection components can be installed by methods such as vacuum deposition, sputtering, and chemical plating, and vacuum deposition is particularly preferred.

A preferable thickness of the specular reflection layer is 0.05 to 2 μm. The specular reflection layer may be a single layer, but two or more of the above components may be laminated.

The radio wave transmissive retroreflective sheet according to the present invention can be preferably used in a retroreflective RFID device that maintains nighttime visibility in combination with an active or passive RFID device.

Further, in communication of an RFID device using weak radio waves, the weak radio waves can be efficiently transmitted, and can be preferably used particularly for a passive RFID device.

Furthermore, it is a radio wave transmissive retroreflective sheet and has excellent retroreflective properties that can sufficiently ensure nighttime visibility.

When such a retroreflective RFID device is used as a retroreflective device when used as a vehicle license plate, a third plate (vehicle recognition sticker attached to a vehicle glass window), or a traffic sign, the communication performance of the RFID device is improved. The requirement of retroreflective performance can be satisfied while ensuring.

A preferred embodiment of the radio wave transmission type retroreflective sheet according to the present invention will be described below with reference to the drawings.

FIGS. 1-5 is a top view which shows the non-specular reflection area | region (1) and specular reflection area | region (2) in this invention. (1) shows a non-specular reflection region, which shows that a linear, bent linear, and / or curved linear region having a width of 0.1 to 1.5 mm is connected. Also, (2) shows a specular reflection area, and the specular reflection area is electrically insulated from each other by a non-specular reflection area where no specular reflection layer is provided, and forms an independent area with a repeated pattern. It is shown that it is installed.

In FIG. 1, it is shown that the non-specular reflection region (1) has a wave-like curve overlapping each other to form the specular reflection region (2) as an independent region.

FIG. 2 shows that the non-specular reflection area (1) is formed by a rectangular line and the hexagonal specular reflection area (2) is formed as an independent area.

In FIG. 3, it is shown that the non-specular reflection area (1) is constituted by a rectangular line and the substantially square specular reflection area (2) is formed as an independent area.

FIG. 4 also shows that the non-specular reflection region (1) is formed by a rectangular line and the hexagonal specular reflection region (2) is formed as an independent region. The shape of the independent region of the hexagonal specular reflection region shown in FIG. 4 is the aspect ratio (L) of the outer edge length (L) in the longest direction of the independent region and the outer edge length (S) in the direction perpendicular thereto. / S) is 2.5.

FIG. 5 shows that the non-specular reflection region (1) is formed by straight lines and the rectangular specular reflection region (2) is formed as an independent region. The rectangular specular reflection region in FIG. 5 is continuous to both ends of the sheet and has a very large aspect ratio.

FIG. 6 shows that in the encapsulated lens type retroreflective sheet which is a preferred embodiment of the present invention, a part of the specular reflection layer (14) does not exist partially and a non-specular reflection region (15) is formed. It is shown.

FIG. 7 shows a cube-corner retroreflective sheet that is another preferred embodiment of the present invention, in which a part of the specular reflection layer (23) is not partially present and a non-specular reflection region (24) is formed. It has been shown.

FIG. 8 shows the interval between adjacent hexagons as P and the width of the non-specular reflection region as W in the retroreflective sheet according to the present invention having the hexagonal specular reflection region shown in FIG. .

FIG. 9 shows the positional relationship between the retroreflective sheet and the RFID tag according to the present invention having the rectangular specular reflection region shown in FIG. In FIG. 9A, the long side direction of the rectangle and the longitudinal direction of the tag are installed in the same direction, and in FIG. 9B, they are installed so as to be at right angles to each other.

Although the description of the following literature can be referred to regarding the specific aspect of the retroreflection sheet | seat in which the specular reflection layer which can be used for this invention was installed, it is not limited to these. In any type of retroreflective sheeting, the non-specular reflection region can be appropriately installed using the method for disposing a non-specular reflection region disclosed above.

Examples of the encapsulated lens type retroreflective sheet include Berisley et al., Japanese Patent Application Laid-Open No. 59-071848 (Patent Document 4) and corresponding US Pat. No. 4,721,649 (Patent Document 5) and US Pat. No. 4,725,494. (Patent Document 6).

Examples of the capsule lens type retroreflective sheet include Mackenzie's Japanese Patent Publication No. 40-007870 (Patent Document 7) and its corresponding US Pat. No. 3,190,178 (Patent Document 8), No.-110592 (Patent Document 9) and the corresponding US Pat. No. 4.025,159 (Patent Document 10), and Bailey et al., Japanese Patent Laid-Open No. 62-121043 (Patent Document 11) and the corresponding US Pat. No. 5,064,272. No. (Patent Document 12) and the like.

Further, as a cube corner retroreflective sheet in which a specular reflection layer is installed, Roland's Japanese Patent Publication No. 8-510415 (Patent Document 13) and its corresponding US Pat. No. 5,376,431 (Patent Document 14), Mimura et al. WO 01/057560 (Patent Document 15) and the corresponding US Pat. No. 6,817,724 (Patent Document 16).

Hereinafter, the details of the present invention will be described more specifically with reference to examples, but it is needless to say that the present invention is not limited to the examples.

<Measurement of retroreflection coefficient>
The retroreflection coefficient described in the present specification including the examples is measured by the method described below. As a retroreflective coefficient measuring instrument, using Gamma Scientific's Model 920, the retroreflective coefficient of the measurement sample of 100 mm x 100 mm is the same as ASTM E810-91, with an observation angle of 0.2 ° and an incident angle of 5 ° Then, the measurement was made 5 times, and the average value was taken as the retroreflection coefficient of the retroreflective article.

<Measurement of radio wave recognition rate by RFID device>
A single-chip system passive RFID tag HDT type is installed in close contact with the back of the measurement sample using an adhesive sheet, and a 9 mm thick glass plate is also installed on the surface of the measurement sample using the same adhesive sheet. The sample was used for measuring the radio wave recognition rate. Using this U519 type scanner and a YAGI antenna with a wavelength of 915MHz and a gain of 10dbi on this measurement sample, the US radio standard FCC
The recognition rate of radio waves was calculated from the number of times a radio signal was transmitted 500 times under the conditions of Part 15 standard and the response was made.

<Measurement of electrical insulation between independent specular reflection areas>
Ten sets of electrical conductivity between two independent specular reflection regions were measured using a commercially available electrical resistance measurement tester. As judgment of electrical conductivity, the case where the electrical resistance by a tester shows a value within 1000Ω was evaluated as having electrical conductivity. Samples that are not electrically conductive at 10 locations are evaluated as insulating samples, samples that are electrically conductive at 5 or more locations are evaluated as semi-insulating samples, and samples that are electrically conductive at 10 locations are non-insulating samples It was.

First, in measurement, sample number 1 is a measurement sample in which a film made of 75 μm polyethylene terephthalate is laminated on the front of the RFID tag instead of a retroreflective sheet, and sample number 2 is normal retroreflection without a non-specular reflection area. Table 1 shows the radio wave recognition rate and the retroreflective coefficient of a measurement sample using a sheet (encapsulated lens type retroreflective sheet manufactured by Nippon Carbide Industries Co., Ltd., Nikkalite MLG). Sample 1 is an insulating material because it is a resin material, and Sample 2 is a non-insulating material with conductivity between any two points because an aluminum specular reflection layer is installed over the entire surface. It was.

Sample No. 1 showed an excellent recognition rate at any reading distance, whereas Sample No. 2 using a conventionally known sample that was not subjected to non-specular reflection processing was radio wave at any reading distance. Could not be recognized.

Next, the encapsulated lens type retroreflective sheet manufactured by Nippon Carbide Industries Co., Ltd., non-specular reflection into the regular hexagonal shape shown in Fig. 2 by laser processing on the specular reflective layer surface where the adhesive layer of Nikkalite MLG is not installed Samples 10 to 24 having been treated were prepared and measured by the above method. Table 2 shows the shape of these samples. The center interval in Table 2 is shown as P in the diagram illustrating the hexagonal shape shown in FIG. Further, the line width of the non-specular reflection area is shown as W in FIG. Moreover, the area ratio of the specular reflection area | region of these samples is shown as a reflection area area ratio.

The recognition rates and retroreflection coefficients of these samples 10 to 24 are also shown in Table 2. Samples 10 to 14 having a line width of 0.20 mm show an excellent recognition rate, and the recognition rate is improved as the reflection area ratio is reduced. However, the change of the retroreflection coefficient was very small. Each sample was an insulating sample.

Samples 15 to 19 having a line width of 0.10 mm show excellent recognition rates as well, and the recognition rate is improved as the reflection area ratio is reduced. However, the change of the retroreflection coefficient was very small. Each sample was an insulating sample.

On the other hand, in Samples 20 to 24 having a line width of 0.05 mm, radio waves could not be recognized at any reflection area ratio. Each sample was a non-insulating sample.

Similarly, a rectangular specular reflection region as shown in FIG. 5 was installed on the specular reflection layer surface on which the adhesive layer of the enclosed lens type retroreflective sheet, Nikkalite MLG manufactured by Nippon Carbide Industries Co., Ltd., was not installed. In Table 3, samples 30a to 37a are installed such that the positional relationship between the retroreflective sheet and the RFID tag in the present invention having a rectangular specular reflection region as shown in FIG. . Further, in the samples 30b to 37b, the center interval and line width of the non-specular reflection region of the sample installed so as to be parallel to each other, and the area ratio of the specular reflection region are shown.

Similarly, Table 3 shows the measured values of the recognition rate and the retroreflection coefficient at each distance of the retroreflective sheet having the rectangular specular reflection region. Both samples have an excellent retroreflection coefficient. All samples were judged to be insulating materials.

Since the samples 30a to 37a are installed so that the positional relationship between the retroreflective sheet and the RFID tag in the present invention having a rectangular specular reflection region is perpendicular, the samples 30a to 37a show an excellent recognition rate. Samples 30a to 33a with a line width of 0.20 mm show a better recognition rate as a whole than samples 34a to 37a with a line width of 0.05 mm.

In addition, among the sample groups having the same line width, a sample with a small center interval of the non-specular reflection region and a smaller reflection region area ratio showed a better recognition rate even at a longer reading distance.

On the other hand, the samples 30b to 37b were installed so as to be parallel to each other, and radio waves could not be recognized in any of the samples.

Therefore, it is important to install the radio wave transmitting retroreflective sheet according to the present invention and the RFID tag antenna so that the antennas are installed at right angles in the radio wave transmitting reflective sheet having such a rectangular specular reflection region. In the case where they are installed in parallel, a preferable radio wave recognition performance cannot be obtained even if the shape of the non-specular reflection region is appropriately formed.

The retroreflective sheet in the present invention can be preferably used in an RFID apparatus that maintains nighttime visibility in combination with an RFID apparatus.

Furthermore, the retroreflective sheet in the present invention is a radio wave-transmitting retroreflective sheet capable of efficiently transmitting weak radio waves in communication of RFID devices using weak radio waves, and is particularly preferably used for passive RFID devices. I can do it.

Further, the retroreflective sheet according to the present invention can use the retroreflective RFID device for a vehicle license plate, a third plate, a traffic sign, or the like.

The top view which shows the non-specular reflection area | region and specular reflection area | region in this invention. The top view which shows the non-specular reflection area | region and specular reflection area | region in this invention. The top view which shows the non-specular reflection area | region and specular reflection area | region in this invention. The top view which shows the non-specular reflection area | region and specular reflection area | region in this invention. The top view which shows the non-specular reflection area | region and specular reflection area | region in this invention. Sectional drawing which shows the enclosure lens type retroreflection sheet in this invention. Sectional drawing which shows the cube corner type retroreflection sheet in this invention. The top view which shows the non-specular reflection area | region and specular reflection area | region in this invention. The figure which shows the relationship between the non-specular reflection area | region, specular reflection area | region, and tag in this invention.

Explanation of symbols

1: Non-specular reflection area
2: Specular reflection area
10: Surface protective layer
11: Retaining layer
12: Glass sphere
13: Focusing layer
14: Specular reflection layer
15: Non-specular reflection area
16: Adhesive layer
20: Surface protective layer
21: Prism holding layer
22: Prism layer
23: Specular reflection layer
24: Non-specular reflection area
25: Adhesive layer

Claims (8)

In the retroreflective sheet in which the specular reflection layer is installed, the specular reflection area in which the specular reflection layer is installed is electrically insulated from each other by the non-specular reflection area in which the specular reflection layer is not installed, and forms an independent area. A radio wave permeable retroreflective sheet that is installed in a repeating pattern and exhibits radio wave transmissivity. 2. The radio wave transmissive retroreflective sheet according to claim 1, wherein the non-specular reflection region is a linear, bent line or / and curved line region having a width of 0.1 to 1.5 mm. 3. The radio wave transmissive retroreflective sheet according to claim 1 or 2, wherein the linear region constitutes a connected region. The shape of the independent region of the specular reflection region is such that the aspect ratio (L / S) between the outer end length (L) in the longest direction of the independent region and the outer end length (S) in the direction perpendicular thereto is 2 or more. The radio wave transmissive retroreflective sheet according to claim 1, wherein the radio wave transmissive retroreflective sheet is provided. 5. The radio wave transmissive retroreflective sheet according to claim 1, wherein the area ratio of the independent region of the specular reflection region is 85 to 99%. 6. The radio wave transmission according to claim 1, wherein the retroreflective element constituting the retroreflective sheet is an encapsulated lens type retroreflective element, a capsule lens type retroreflective element, or a cube corner type retroreflective element. Retroreflective sheet. 7. The radio wave transmissive retroreflective sheet according to claim 1, wherein the specular reflection layer component constituting the specular reflection layer is aluminum, silver, nickel, and / or copper. 8. The radio wave transmissive retroreflective sheet according to claim 1, wherein the region forming the non-specular reflection region is a part of the retroreflective sheet.