JP2009124485A - Resin molded article disposed on beam path of radio wave radar device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize a three-dimensional design while suppressing increase in a transmission loss. <P>SOLUTION: A transparent resin layer includes a general part and a projecting part which is thicker than the general part and protrudes its surface from a top layer, and at least a portion of the projecting part is formed from a thermoplastic resin having such characteristics that a dielectric loss tangent at a frequency of beam is 0.0005 or less and a relative dielectric constant is 3 or less. The projecting part is formed from the thermoplastic resin, thereby extremely reducing a transmission loss of millimeter waves when transmitting through the projecting part. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a resin molded product disposed in a beam path of a radio wave radar device such as a millimeter wave radar device or a microwave radar device.

  The auto-cruise system measures the distance and relative speed between the vehicle in front and the vehicle using sensors mounted in front of the vehicle, and controls the throttle and brake based on this information to accelerate and decelerate the vehicle. This is a technology to control the distance. In recent years, this auto-cruise system has attracted attention as one of the core technologies of the Intelligent Transport System (ITS) aiming to reduce traffic congestion and reduce accidents.

  Generally, a laser radar or a millimeter wave radar is used as a sensor used in an auto cruise system. Among these, the millimeter wave radar transmits this millimeter wave using a millimeter wave having a frequency of 30 GHz to 300 GHz and a wavelength of 1 to 10 mm, and receives the millimeter wave reflected on the object, thereby transmitting this millimeter wave. The distance between the vehicle ahead and the vehicle and the relative speed are measured from the difference between the wave and the received wave.

  Since the millimeter wave has a short wavelength, it is possible to downsize the millimeter wave radar using the millimeter wave. In addition, because millimeter waves have a large reflection coefficient for good conductors such as metals, they can identify vehicles well and have characteristics that are less susceptible to fog, snow, sunlight, etc. compared to lasers. Therefore, the millimeter wave radar using the millimeter wave is suitably used as an in-vehicle radar.

  The millimeter wave radar is generally arranged on the back side of the front grill of the vehicle. However, the front grill is often plated with metal, and it is difficult to satisfactorily transmit millimeter waves having a large metal reflection coefficient. Also, the front grille has a structure with a vent hole for taking in air and does not have a uniform wall thickness. A difference in millimeter wave transmission speed occurs between the thin and thick portions, and the accuracy of the auto-cruise system decreases.

  Under such circumstances, it is common to provide a window portion through which millimeter waves can be transmitted at a portion of the front grill corresponding to a portion where the millimeter wave radar is disposed. When providing a window part in a front grill, it becomes possible to let a millimeter wave go in and out through this window part. However, the appearance of the front grille is lost due to the provision of the window, and the inside of the vehicle, for example, the millimeter wave radar device or the engine room, is visually observed from this window, so that the appearance of the vehicle is There is a risk of damage.

  Therefore, conventionally, for example, a covering component as disclosed in Japanese Patent Application Laid-Open No. 2000-159039 is inserted into the window portion of the front grill so that the window portion and the front grill body have a sense of unity. The covering component disclosed in the publication is formed by laminating a plurality of resin layers formed with unevenness, and the fin member of the front grille is covered with the metal layer deposited with unevenness between the resin layers. It gives the impression that it exists continuously inside.

  However, if such a covering component is arranged in the beam path of the millimeter wave radar, the accuracy of the auto cruise system is reduced due to the transmission loss. Therefore, it is necessary to reduce the transmission loss as much as possible. Therefore, Japanese Patent Laid-Open No. 2002-135030 discloses that a radio wave transmissive outer surface coating plate having a metal film on the inner surface and a radio wave transmissive rear surface coating plate are laminated to form an outer surface coating plate and a back surface coating plate. There has been proposed a radio wave transmissive exterior part cost in which the relative permittivity of the material to be made is substantially the same. In this way, by configuring the outer cover plate and the rear cover plate from materials having substantially the same relative dielectric constant, it is possible to effectively suppress the refraction and reflection of radio waves and to reduce transmission loss.

  Japanese Patent Laid-Open No. 2003-252137 discloses a method in which a metal thin film is formed on one surface of a plate-like base material, and a part of the metal thin film is physically or chemically removed to form an island-like bright part. There has been proposed a method for manufacturing a radio wave transmission cover in which a transparent resin layer is formed on the upper surface of the surface on which the bright part is formed.

  Further, JP-A-2004-251868 discloses a transparent resin layer having an exposed surface, a base material layer, and a decorative body layer that is laminated in a gap between the transparent resin layer and the base material layer and displays a design through the transparent resin layer. Proposed a radio wave transmission cover characterized in that the decorative body layer includes a luminous piece having a vapor deposition design surface on which a metal material whose crystal extends in the vapor deposition direction is deposited so as to become a predetermined design Has been.

In these publications, when polycarbonate (PC) is used as the transparent resin layer, the base layer is formed from acrylonitrile / ethylene propylene / styrene polymer (AES) whose relative dielectric constant is substantially the same as polycarbonate. It is stated that it is desirable. However, even with resin molded products made of PC and AES, the radio wave attenuation is still 1.3 to 1.8 dB, which is still large, and it is required to further reduce the radio wave attenuation, that is, to further reduce the transmission loss. .
JP 2000-159039 JP 2002-135030 JP2003-252137 JP 2004-251868

  By the way, in the resin molded product arranged in the beam path of the above-described millimeter wave radar device, it is necessary to make the thickness in the radio wave transmission range uniform in order to prevent variation in transmission loss due to the transmission part. However, such a resin molded product has a problem that the design surface is low because the design surface is flat and flat.

  Therefore, it is conceivable to form a two-layered resin molded product, form a stepped portion at the interface, and express a three-dimensional design at the stepped portion. However, when manufacturing by injection molding, there exists a minimum wall thickness that can be molded. Therefore, in order to form a stepped portion at the interface between the two layers, in order to make the thickness of one of the two layers at the stepped portion equal to or greater than the minimum moldable thickness, at least one of the two layers However, there was a problem that the transmission loss increased.

  Further, it is conceivable to form a three-dimensional design by forming a convex portion on the surface of the transparent resin layer. It is known that the transmission loss when passing through the transparent resin layer is reduced when the thickness of the transparent resin layer is an integer (n) times 1/2 of the beam wavelength (λ). Therefore, if the thickness of the convex portion satisfies this restriction, a three-dimensional design can be achieved while suppressing an increase in transmission loss.

  However, in this case, the thickness of the general part other than the convex part in the transparent resin layer must satisfy the above-mentioned regulations, so that the thickness of the convex part of the transparent resin layer becomes too thick when the conventional material is used. As a result, there is a problem that transmission loss increases and the required design is difficult to be expressed.

  This invention is made | formed in view of such a situation, and makes it the subject which should be solved to enable it to express a solid design with a high degree of freedom, suppressing the increase in transmission loss.

  The resin molded product arranged in the beam path of the radio wave radar device of the present invention that solves the above problems is a resin molded product arranged in the beam path of the radio wave radar device on the back side, and is exposed on the outer surface. A transparent resin layer having an exposed surface and a base material layer formed on the surface opposite to the exposed surface of the transparent resin layer, and the transparent resin layer is thicker than the general part and the general part. A convex portion whose surface protrudes from the exposed surface, and at least a part of the convex portion is formed of a thermoplastic resin having characteristics of a dielectric loss tangent at a beam frequency of 0.0005 or less and a relative dielectric constant of 3 or less. There is to be.

  The thickness difference (Δh) between the convex portion and the general portion is substantially equal to an integer (n) times 1/2 (Δh = nλ / 2) of the wavelength (λ) of the beam transmitted through the convex portion. Is desirable.

  The convex portion is desirably formed in a size close to the boundary between the radio wave transmission range and the radio wave non-transmission range within the radio wave transmission range. Moreover, you may form the whole transparent resin layer from this thermoplastic resin. The thermoplastic resin is preferably a cycloolefin resin.

  Moreover, when at least a convex part is formed from cycloolefin type resin, the fine convex part of thickness smaller than the thickness of a convex part can be formed in the surface of a convex part. Desirably, a polycarbonate layer is formed on the surface of the convex portion, and a hard coat layer is formed on the surface of the polycarbonate layer.

  According to the resin molded product of the present invention, since the convex portions are formed on the transparent resin layer, a three-dimensional design is possible, and the degree of freedom of design is dramatically increased. Since at least a part of the convex portion is formed of a thermoplastic resin having a characteristic that the dielectric loss tangent at the beam frequency is 0.0005 or less and the relative dielectric constant is 3 or less, the radio waves of the beam pass through the convex portion. Transmission loss can be made extremely small.

  Further, the difference in thickness (Δh) between the convex portion and the general portion is substantially equal to an integer (n) times 1/2 (Δh = nλ / 2) of the wavelength (λ) of the radio wave transmitted through the convex portion. For example, the transmission loss when the radio wave of the beam passes through the convex portion can be further reduced. Therefore, it is possible to maintain high accuracy of the auto cruise system while expressing the three-dimensional design by the convex portion.

  The resin molded product of the present invention has a transparent resin layer and a base material layer. The base material layer and the transparent resin layer need to be formed from a resin having a small radio wave transmission loss. In consideration of moldability, PC, AES, cyclopolyolefin (COP), or the like can be used. The transparent resin layer needs to have high transparency, and it is desirable to use PC or COP. The base material layer does not need to be transparent, but may be transparent. In that case, PC or COP can be used.

  Polypropylene (PP) has a dielectric loss tangent at a beam frequency of 76.5 GHz of a commonly used millimeter wave radar device as small as 0.0003 and a relative dielectric constant as small as 2.3. Therefore, the transmission loss satisfies the target value. However, since the molding shrinkage ratio is as large as 1.6 to 1.9, it is not preferable in view of moldability. The dielectric loss tangent (tan δ) is a dielectric index also called dielectric loss. The dielectric loss tangent of a commonly used millimeter wave radar device at a beam frequency of 76.5 GHz is 0.001 for PC, 0.001 for AES, and 0.00025 for COP, and any of them can be preferably used.

  Cyclopolyolefin (COP) is a polyolefin having a repeating unit having a saturated alicyclic structure. Some of them may contain an unsaturated bond. Specific examples of the alicyclic structure include a cycloalkane structure and a cycloalkene structure, and a cycloalkane structure is preferable. The number of carbon atoms constituting the alicyclic structure is usually 4 to 30, preferably 5 to 20, and more preferably 5 to 15. Examples of the monomer used as a raw material include norbornene, cyclohexene, vinylcyclohexane, and alkyl-substituted and alkylidene-substituted products thereof.

  For example, when a transparent resin layer composed of a general part and a convex part is formed from PC, the thickness difference (Δh) between the convex part and the general part is 1 / (1) of the wavelength (λ) of the radio wave transmitted through the convex part. An integer (n) times 2 (Δh = nλ / 2), and the thickness (H) of the general part is also an integer (n) that is ½ of the wavelength (λ) of the radio wave transmitted through the general part. Double. Specifically, when a radio wave having a beam frequency of 76.5 GHz of a commonly used millimeter wave radar device passes through the PC, Δh = 1.2n or H = 1.2 m (m is an integer). With this configuration, transmission loss can be reduced.

  However, even if the convex part and the general part are formed from the PC so as to satisfy the above-described regulation of Δh, for example, when the beam is transmitted obliquely, the above condition of Δh is not satisfied, and the transmission loss increases. End up.

  Therefore, in the resin molded product of the present invention, at least a part of the convex portion is formed from a thermoplastic resin having the characteristics that the dielectric loss tangent at the frequency of the transmitted radio wave is 0.0005 or less and the relative dielectric constant is 3 or less. Accordingly, at least a part of the convex portion formed from this thermoplastic resin has a very small transmission loss, so that the above-described regulation of Δh is relaxed and the convex portion can be formed with a relatively free thickness. If the dielectric loss tangent is larger than 0.0005 or the relative dielectric constant exceeds 3, the transmission loss becomes larger than the target due to refraction and reflection of radio waves. Examples of the thermoplastic resin having such characteristics include the COP described above.

  Even when the convex portion is formed of COP, the transmission loss can be further reduced if Δh is substantially Δh = nλ / 2. When radio waves pass through the dielectric, the wavelength changes depending on the material of the dielectric. Therefore, the wavelength (λ) of the radio wave that passes through the convex part differs between PC and COP. When radio waves with a frequency of 76.5 GHz of a commonly used millimeter-wave radar device are transmitted, the convex part made of PC Δh = 1.2n, and in the case of a convex portion made of COP, Δh = 1.3n. However, since the transmission loss of COP is extremely small, there is no practical problem even if Δh = 1.3n is not set accurately.

  When the convex portion is formed from COP, the PC layer may be formed in the lower layer of the convex portion, the entire thickness of the convex portion is formed from COP, and the general portion around the convex portion is formed from PC. Also good. Or the whole transparent resin layer can also be formed from COP. When the PC layer is formed in the lower layer of the convex portion formed of COP, the thickness of the convex portion does not need to be an exact multiple of 1.3 as described above, but the thickness of the lower PC layer is 1.2. Must be an integer multiple. When the total thickness of the convex portion is formed from COP and the general portion around the convex portion is formed from PC, the total thickness of the convex portion is preferably close to an integral multiple of 1.3. The thickness should be an integer multiple of 1.2.

  By the way, when the radio wave is transmitted with an inclination rather than perpendicular to the design surface, the substantial thickness does not satisfy Δh = nλ / 2 when the radio wave is transmitted through the step portion between the convex portion and the general portion. In some cases, transmission loss may increase. Therefore, in the case of a convex part that occupies a large area on the design surface or a convex part that is long in the left-right or vertical direction of the design surface, the convex part has a radio wave transmission range and a radio wave non-transmission range within the radio wave transmission range. It is desirable to form it in a size close to the boundary portion. By forming the convex portion in this way, the above-described problems are less likely to occur.

  In the resin molded product arranged in the beam path of the radio wave radar device, it is desired to increase the surface hardness in order to prevent scratches. Therefore, conventionally, a hard coat layer is formed on the surface, but COP has a problem that the hard coat layer cannot be formed on the surface of the convex portion because the adhesion of the hard coat layer is poor.

  Therefore, it is desirable to form a thin PC layer on at least the surface of the convex portion and to form a hard coat layer on the surface. In order to form the PC layer, there is a method of bonding a PC film.

  The base material layer can be formed of PC, COP, AES or the like. Incidentally, AES used in the past has excellent moldability since the molding shrinkage ratio is as small as 0.4%, and the relative dielectric constant is 2.56. Therefore, refraction and reflection of radio waves are suppressed and transmission loss is also reduced. The dielectric loss tangent at the frequency of 76.5 GHz is 0.001, which is equivalent to that of PC, and the wall thickness regulation is the same as that of PC.

  The resin molded product of the present invention preferably has a decorative layer. If the base material layer is transparent, the decorative body layer can be formed on the back surface, the interface between the base material layer and the transparent resin layer, the inside of the transparent resin layer, and the like. This decorative body layer displays a design on the exposed surface through the transparent resin layer, and a film-like decorative body layer may be laminated, or the surface opposite to the exposed surface of the transparent resin layer or the base material layer A decorative layer may be formed on the surface facing the transparent resin layer by printing, painting, or the like.

  Moreover, as a decorating body layer, the fine uneven | corrugated pattern of thickness smaller than the thickness of a convex part can also be formed in the surface of a convex part. In particular, when the convex portion is formed of COP, the dielectric loss tangent at the frequency of the transmitted radio wave has a characteristic of 0.0005 or less and the relative dielectric constant is 3 or less, so that the thickness variation has little influence on the transmission loss.

  In order to manufacture the resin molded product of the present invention, for example, first, a transparent resin layer having a decorative body layer is formed. The transparent resin layer can be formed by various molding methods such as injection molding, press molding, and potting.

  In order to form a decorative body layer, it can be directly formed on a previously formed transparent resin layer by painting, printing, vapor deposition or the like. In addition, a film on which a predetermined design is formed in advance is placed in a mold, and after the transparent resin layer is molded in the mold, the film is peeled off to transfer the design onto the surface of the transparent resin layer, You can also

  Thereafter, a transparent resin layer having a decorative body layer is placed in the mold, and a base material layer is formed. For example, AES has a glass transition temperature lower than that of PC and is excellent in molding fluidity and molding shrinkage. Therefore, since the molding temperature at the time of injection molding is not too high, there is no problem that the decorative body layer is destroyed. Further, since distortion during molding is small, warping and cracking can be prevented. Therefore, it is possible to easily and inexpensively manufacture a resin molded product having excellent design properties and shape accuracy and low transmission loss.

  Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples.

Example 1
FIG. 2 shows a resin molded product of this example. This resin molded product is an emblem 1 provided on a front grill 100 of an automobile as shown in FIG. 1, and is held in a window formed in the front grill 100 by a fixing means such as a bracket or a bolt (not shown). Yes. Behind the emblem 1, a millimeter wave radar device (not shown) as an in-vehicle radar device is disposed at a position separated from the back surface by a predetermined distance. The millimeter wave radar device transmits and receives a millimeter wave beam having a frequency of 76.5 GHz, and an emblem 1 is interposed in the beam path.

  The emblem 1 includes a base material layer 2, an indium layer 3, a black background layer 4 partially formed on the surface of the indium layer 3, and a transparent side from the rear side of the vehicle (the surface side facing the millimeter wave radar device). And a resin layer 5. The base material layer 2 is made of black opaque AES, and the transparent resin layer 5 is made of COP. The transparent resin layer 5 includes a general portion 50 having a substantially uniform thickness and a convex portion 51 protruding from the surface of the general portion 50. When viewed from the outside of the vehicle, a part of the black background layer 4 and the indium layer 3 is visually recognized from the surface of the transparent resin layer 5, and an emblem design in which a metallic glitter portion is floated on the black background is visually recognized. Moreover, since the convex part 51 is formed corresponding to the site | part which the indium layer 3 exposes, a glittering layer appears on the inner layer of the solid design of the convex part 50, and the design with a three-dimensional effect is exhibited.

  In FIG. 3, the typical sectional drawing of the resin molded product of a present Example is shown. The transparent resin layer 5 includes a general portion 50 and a convex portion 51, and is entirely made of COP. The thickness of the general portion 50 is 1.3 × 3 = 3.9 mm, and the convex portion 51 is 1.3 × 2 = 2.6 mm.

  This emblem 1 was manufactured as follows.

  First, cyclopolyolefin was injected to form the general portion 50 and the convex portion 51, and the transparent resin layer 5 was formed. On the back surface of the transparent resin layer 5 (surface facing the base material layer 2), an uneven shape with a slight step is formed. 2 and 3, this step size is exaggerated.

  Next, a black background layer 4 having a film thickness of several μm was formed from a black paint only on the convex surface on the back surface by screen printing. Next, using indium, an indium layer 3 was deposited on the entire back surface to a thickness of 300 mm. Thereby, from the surface side of the transparent resin layer 5, the bright portion composed of the indium layer 3 formed on the concave surface on the back surface, the black background layer 4 formed on the convex surface on the back surface, the general portion 50 and the convex portion on the surface. The part 51 is visually recognized.

  A transparent resin layer 5 having a decorative layer obtained as described above is placed in a mold, and a substrate having a substantially uniform thickness (1.2 mm) from black acrylonitrile / ethylene propylene / styrene polymer (AES). Layer 2 was injection molded.

(Example 2)
The resin molded product of this example had a decorative body layer that the base material layer 2 and the transparent resin layer 5 were integrally formed from COP, as shown in a schematic cross section in FIG. The configuration is substantially the same as that of the first embodiment except that the configuration is not present. The thickness of the general portion 50 of the transparent resin layer 5 is 1.3 × 6 = 7.8 mm, and the thickness of the convex portion 51 is 1.3 × 2 = 2.6 mm.

(Example 3)
In the resin molded product of this example, as shown in a schematic cross section in FIG. 5, a convex portion 51 ′ having a slight step is formed on the back surface side of the transparent resin layer 5, and the back surface except for the surface of the convex portion 52 is black. The ground layer 4 is formed, and the indium layer 3 is formed on the surface of the convex portion 51 ′ and the surface of the black ground layer 4. Further, a PC film layer 6 is laminated on the surface of the transparent resin layer 5, and a hard coat layer 7 is formed on the surface of the PC film layer 6. Other configurations are the same as those of the first embodiment.

  According to the resin molded product of this example, the hard coat layer 7 prevents the design surface from being scratched, and the PC film layer 6 prevents problems such as peeling of the hard coat layer 7. And since the convex part 51 and convex part 51 'have comprised the substantially convex lens shape, the design of the indium layer 3 is expanded and visually recognized, and high designability is expressed.

Example 4
In the resin molded product of this example, as shown in a schematic cross section in FIG. 6, the convex portion 51 in the transparent resin layer 5 is formed with the entire thickness of the transparent resin layer 5, and the general portion 50 is formed from PC. The configuration is substantially the same as in Example 1 except that the PC film layer 6 is laminated on the surface of the transparent resin layer 5 and the hard coat layer 7 is formed on the surface of the PC film layer 6. The thickness of the general part 50 is 3.9 mm, and the thickness of the convex part 51 is 6.5 mm.

(Example 5)
The resin molded product of the present embodiment is established even if it is not an integer (n) times 1/2 (Δh = nλ / 2) of the beam wavelength (λ). FIG. 7 shows a schematic cross section as an example. An uneven pattern 52 having a height of 0.3 mm is formed on the surface of the convex portion 51, a PC film layer 6 is laminated on the surface of the transparent resin layer 5, and a hard coat layer 7 is formed on the surface of the PC film layer 6. Except for this, this is the same as Example 2.

  Since the convex portion 52 is formed of COP, even if the concave / convex pattern 52 is formed in this way, the thickness variation has little influence on the transmission loss. Therefore, it is possible to form the uneven pattern 52 that has been difficult in the past, and the degree of freedom in design is high.

(Example 6)
As shown in a schematic cross section in FIG. 8, the resin molded product of this example is composed of a base material layer 2 ′ made of COP and a transparent resin layer 5 made of COP, and the base material layer 2 ′ and the transparent resin layer. An indium layer 3 and a black background layer 4 are formed therebetween. The base material layer 2 ′ and the transparent resin layer 5 are formed from the same COP by two-color molding.

  According to the resin molded product of this example, since the base material layer 2 ′ and the transparent resin layer 5 are formed from COP, the regulation of each thickness is relaxed. Accordingly, it is possible to form a large step as shown in FIG. 8 in the shape of the indium layer 3, and the degree of freedom in the design of the bright surface is high.

(Comparative Example 1)
A resin molded product having the same shape as in Example 2 was formed from PC. The thickness of the general portion 50 is 1.2 × 6 = 7.2, and the thickness of the convex portion 51 is 2.0 mm which is not an integral multiple of 1.2.

<Evaluation>
The resin molded products of Examples 1 to 6 and Comparative Example 1 were irradiated with a beam having a frequency of 76.5 GHz so as to be perpendicularly incident on the surface of the convex portion 51 from the millimeter wave radar device, and the transmission loss at that time was measured. The results are shown in Table 1 as relative values with the transmission loss of Comparative Example 1 as 100.

  From Table 1, the resin molded products of Examples 1 to 6 have smaller radio wave attenuation than the resin molded product of Comparative Example 1. That is, the resin molded product of the present invention has high radio wave permeability despite having the convex portions 51.

  The resin molded product of the present invention can also be used as a front grill, a bumper, a back garnish, a spoiler, a part of a side molding, and the like.

It is a principal part perspective view of the motor vehicle which has the resin molded product which concerns on one Example of this invention. It is sectional drawing of the resin molded product which concerns on one Example of this invention. It is typical sectional drawing which shows the principal part of the resin molded product which concerns on one Example of this invention. It is typical sectional drawing which shows the principal part of the resin molded product which concerns on the 2nd Example of this invention. It is typical sectional drawing which shows the principal part of the resin molded product which concerns on the 3rd Example of this invention. It is typical sectional drawing which shows the principal part of the resin molded product which concerns on the 4th Example of this invention. It is typical sectional drawing which shows the principal part of the resin molded product which concerns on the 5th Example of this invention. It is typical sectional drawing which shows the principal part of the resin molded product which concerns on the 6th Example of this invention.

Explanation of symbols

1: Emblem (resin molded product) 2: Base material layer 3: Indium layer 4: Black ground layer 5: Transparent resin layer 6: PC film layer 7: Hard coat layer 50: General part
51: Convex part 52: Concave and convex pattern

Claims (7)

It is a resin molded product placed in the beam path of the radio wave radar device on the back side,
A transparent resin layer having an exposed surface exposed on the outer surface, and a base material layer formed on the surface of the transparent resin layer opposite to the exposed surface,
The transparent resin layer has a general part, and a convex part whose surface is thicker than the general part and whose surface projects from the exposed surface,
At least a part of the convex part is formed from a thermoplastic resin having a characteristic that a dielectric loss tangent at a frequency of the beam is 0.0005 or less and a relative dielectric constant is 3 or less.   The difference in thickness (Δh) between the convex portion and the general portion is substantially equal to an integer (n) times 1/2 (Δh = nλ / 2) of the wavelength (λ) of the beam transmitted through the convex portion. The resin molded product according to claim 1 which is equal to each other.   3. The resin molded product according to claim 1, wherein the convex portion is formed in a size close to a boundary portion between the radio wave transmission range and the radio wave non-transmission range within the radio wave transmission range.   The resin molded product according to any one of claims 1 to 3, wherein the entire transparent resin layer is formed from the thermoplastic resin.   The resin molded product according to any one of claims 1 to 4, wherein the thermoplastic resin is a cycloolefin resin.   The resin molded product according to claim 1, wherein a surface of the convex portion has a fine convex portion having a thickness smaller than that of the convex portion.   The resin molded product according to claim 5 or 6, wherein a polycarbonate layer is formed on a surface of the convex portion, and a hard coat layer is formed on the surface of the polycarbonate layer.

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