JP2008187383A - Film antenna, power supply device, and receiving system for traveling object - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a non-directional film antenna for inputting/outputting a signal through a coaxial cable without providing any balanced/unbalanced converter at a power feeding part. <P>SOLUTION: This film antenna 10 is formed by laminating an antenna conductor configured of a conductors 52a, 54a, 52b and 54b on a transparent film 50. The antenna conductor is basically configured of a two-wire folded di-pole antenna shown by (b), and the width of one conductors 52a and 52b of a pair of conductors arranged in parallel is set so as to be wider than that of the other conductors 54a and 54b so that characteristic impedances can be matched with a coaxial cable. Also, an antenna conductor is laminated on the transparent film 50 in such a state that it is bent like an L character, and the conductors 52b and 54b are provided with inductors 56 and 58 for delaying the phase of a reception signal by 90 degrees. As a result, the film antenna 10 is configured as a non-directional antenna suitable for a traveling object. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention mainly relates to a film antenna that is used by being mounted on a glass of a mobile body, a power supply device that supplies power to the film antenna, and a mobile body that includes the film antenna and the power supply device. Receiving system

  Conventionally, as a film antenna that is attached to a window glass of a house or an automobile and receives a television broadcast, an antenna film (folded dipole antenna) made of a mesh-like conductor is laminated on an insulating transparent film. (For example, see Patent Document 1).

  According to the proposed film antenna, the area of the mesh hole of the conductor constituting the antenna conductor is adjusted so as to satisfy the bandwidth and field of view of the received signal, thereby obstructing the user's view. Thus, a desired broadcast signal can be received.

  However, in the proposed film antenna, the antenna conductor forms a dipole antenna and has directivity. Therefore, when used in a moving body such as an automobile, the signal of the received signal is accompanied by a change in the traveling direction of the moving body. There has been a problem that the level has changed greatly and the area where broadcast radio waves can be normally received becomes narrow.

On the other hand, as an omnidirectional antenna suitable for mounting on a mobile object, two linear antenna elements having a length (λ / 4) of about a quarter of the wavelength λ of the received signal are used. There is known a turn-style antenna that is arranged in an L shape, and one antenna element is provided with an element (capacitor, inductor, etc.) that shifts the phase of a received signal by 90 degrees compared to the other antenna element (for example, a patent Reference 2 etc.).
JP 2000-124730 A Japanese Patent No. 3349666 (see in particular FIG. 7 and paragraphs 0036-0041)

  For this reason, when manufacturing an omnidirectional film antenna suitable for mounting on a moving body, the antenna conductors laminated on the transparent film are combined with the techniques of the above-mentioned publications to form straight lines made of mesh-like conductors. It is only necessary to form two antenna elements having a shape in an L shape and to provide an element for phase adjustment on one of the antenna elements.

  However, as described in Patent Document 2, the turn-style antenna is a balanced dipole antenna. Therefore, when the antenna conductor is configured with a turn-style antenna in the film antenna, the antenna directivity is suitable for a moving object. However, in order to use a common coaxial cable for transmission of a received signal, a balanced-unbalanced converter must be provided in the feeding portion of the film antenna. There was a problem of inviting.

  The present invention has been made in view of these problems, and makes it possible to input / output a signal via a coaxial cable without making the film antenna omnidirectional, and without providing a balanced-unbalanced converter in the power feeding section. The purpose is to do.

  In order to achieve the above object, the invention according to claim 1 is a film antenna formed by laminating an antenna conductor on an electrically insulating film, wherein the antenna conductor is linear and has a different width. A two-wire folded dipole antenna in which characteristic impedance is set to match a coaxial cable for transmission of communication signals by arranging two conductors substantially in parallel and connecting both ends of each conductor. In contrast, the antenna conductor as a whole is bent in an L shape with the feeding point as the center, and the communication signal is compared with the antenna portion that forms one straight portion of the L shape compared to the antenna portion that forms the other straight portion. It is characterized by being laminated in a state in which phase-shifting means for shifting the phase of each is shifted by approximately 90 degrees.

  The invention according to claim 2 is the film antenna according to claim 1, wherein the film antenna has a connection terminal to which the coaxial cable can be connected and a reception signal from the antenna conductor to amplify the signal. An amplifying unit having an amplifying unit that outputs to the connecting terminal and a power source separating unit that extracts the power supply voltage input to the connecting terminal from the outside and supplies it to the amplifying unit is mounted.

  On the other hand, the invention described in claim 3 is a power supply device that supplies power to the amplification unit of the film antenna according to claim 2 via a coaxial cable, and the film antenna is connected via the coaxial cable. Detecting means for detecting the signal level of the received signal transmitted from the receiver, and determining whether the signal level detected by the detecting means is higher than the determination level. If the signal level is high, the voltage is high. And voltage setting means for setting a power supply voltage to be supplied to the amplification unit so that the voltage is lowered when the signal level is low.

  According to a fourth aspect of the present invention, in the power supply device according to the third aspect, the received signal transmitted from the film antenna via the coaxial cable is amplified to a predetermined target level to be transmitted to the terminal side. And an amplifying circuit with an automatic gain adjusting circuit.

  Next, the invention according to claim 5 is the power supply device according to claim 3 or claim 4, wherein a plurality of inputs for inputting received signals from a plurality of film antennas via the coaxial cable, respectively. And a mixing circuit for mixing the reception signals input to the plurality of input terminals.

  According to a sixth aspect of the present invention, in the power supply device according to the fifth aspect, the detecting means detects a signal level of the received signal input to each of the input terminals, and the voltage setting means is The power supply voltage is set based on the highest signal level among the signal levels detected by the detecting means.

  Further, the invention according to claim 7 is the power supply device according to claim 3 or claim 4, wherein a plurality of input terminals for inputting received signals from a plurality of film antennas, respectively, and the plurality of inputs And a selection circuit that selects a reception signal having a high signal level as an output signal to the terminal among the reception signals input to the terminal.

  Next, the invention according to claim 8 or claim 9 is for a mobile object suitable for receiving broadcast radio waves in a mobile object in which the direction of arrival of radio waves as viewed from a film antenna mounted on glass or the like changes. It relates to a receiving system.

  An eighth aspect of the present invention is directed to a mobile reception system comprising the film antenna according to the second aspect and the power supply device according to the third or fourth aspect. The mobile receiving system according to claim 1 includes a plurality of film antennas according to claim 2 and the power supply device according to any one of claims 5 to 7.

  2. The film antenna according to claim 1, wherein the antenna conductor laminated on the film has two conductors having a linear shape and different widths arranged substantially in parallel to each other to connect both ends of each conductor, thereby providing a characteristic impedance. Constitutes a two-wire folded dipole antenna set so as to be matched with a coaxial cable for communication signal transmission.

  The antenna conductor is bent in an L shape with respect to the feeding point as a center with respect to the film, and the communication signal is compared with the antenna portion that forms one straight portion of the L shape compared to the antenna portion that forms the other straight portion. Are stacked in a state in which phase-shifting means for shifting the phase is shifted by approximately 90 degrees.

  Therefore, according to the film antenna of the present invention, similarly to the turn style antenna described in Patent Document 2, the film surface (in other words, the L-shape of the antenna conductor) is arranged so as to be horizontal, thereby making the horizontal plane omnidirectional. If it is used by attaching it to a surface that is as horizontal as possible on the moving body, such as the windshield of an automobile, the radio waves transmitted from the terrestrial broadcasting station can be stabilized without being affected by the traveling direction of the moving body. It will be possible to receive.

  In particular, in the film antenna of the present invention, the antenna conductor is a two-wire folded dipole antenna, and by setting the widths of the two conductors constituting the antenna conductor to different widths, the characteristic impedance is The characteristic impedance (generally 50Ω or 75Ω) is set to be substantially the same as that of the coaxial cable for communication signal transmission.

  For this reason, when inputting / outputting a signal to / from the film antenna of the present invention via a coaxial cable, it is not necessary to provide a balanced-unbalanced converter in the power supply unit, and the structure of the power supply unit is simplified, The antenna can be reduced in size and weight.

  Next, the film antenna according to claim 2 includes a connection terminal for connecting a coaxial cable, an amplifying means for amplifying a received signal, and a power source that extracts a power supply voltage input to the connecting terminal and supplies the power to the amplifying means. An amplification unit equipped with a separating means is attached.

For this reason, the received signal is amplified and output from the film antenna, and the received signal can be stably supplied to the receiving device to the terminal side.
By the way, when the amplification unit is provided in the film antenna, it is necessary to supply power to the amplification unit from the terminal side. However, when the receiving device on the terminal side does not have a power supply function, the film antenna is connected to the terminal side. A power supply device may be provided on the transmission path of the reception signal to the.

  The power supply apparatus may be configured to supply power to the amplification unit via a coaxial cable. The power supply apparatus includes a detection unit, a voltage setting unit, and a voltage setting unit. Means may be provided.

  That is, in the power supply device according to claim 3, the detection means detects the signal level of the received signal transmitted from the film antenna via the coaxial cable, and the voltage setting means detects the detected signal level. The power supply voltage supplied to the amplification unit is set so that the voltage is high when the signal level is high and the voltage is low when the signal level is low.

  For this reason, when the signal level of the reception signal is low and the noise component generated by the amplification operation of the amplification unit affects the reception signal, the drive voltage of the amplification unit is set low (in other words, in order to suppress the noise component). If the signal level of the reception signal is high and the maximum output level of the amplification unit needs to be increased, the output from the amplification unit is saturated at a low level and the reception signal is Thus, the drive voltage of the amplifying means can be increased so that no distortion occurs.

  Next, this power supply device is provided on a transmission path (coaxial cable) for transmitting a reception signal from the film antenna, and outputs the reception signal to the receiving device on the terminal side. As described in claim 4, an amplification circuit with an automatic gain adjustment circuit for amplifying the received signal to a predetermined target level and outputting it to the terminal side may be provided.

  In other words, if an amplifier circuit with an automatic gain adjustment circuit is provided in the power supply device, it is possible to output a constant level of reception signal to the receiving device on the terminal side, and stable reception without level fluctuation to the receiving device A signal can be transmitted.

  Next, in the power supply device according to claim 5, a plurality of input terminals for respectively inputting reception signals from the plurality of film antennas, and a mixing circuit for mixing the reception signals input to these input terminals And are provided.

Therefore, according to this power supply device, a diversity reception system using a plurality of film antennas can be easily configured.
In this power supply device, when the detection means detects the signal level of the reception signal mixed by the mixing circuit, the power supply voltage supplied to the amplification unit of each film antenna is received from each film antenna. It is set according to the signal level (in other words, the average level) obtained by adding the signals, and the power supply voltage for the amplification unit of the film antenna having a high signal level of the received signal becomes too low, and is finally passed through the mixing circuit. It is conceivable that the quality of the received signal that is obtained automatically decreases.

  For this reason, in the power supply device according to claim 5, as described in claim 6, the detection means detects the signal level of the reception signal input to each input terminal, and the voltage setting means Of the detected signal levels, the power supply voltage may be set based on the highest signal level.

  In other words, in this way, the power supply voltage suitable for the film antenna having the highest signal level of the received signal is set in the voltage setting means, the output from the film antenna is distorted, and the mixing circuit Thus, it is possible to prevent the quality of the reception signal finally obtained via the deterioration.

  In addition, the power supply device according to claim 7 has a plurality of input terminals for inputting received signals from the plurality of film antennas, and a signal level of the received signals input to these input terminals. And a selection circuit that selects a high received signal as an output signal to the terminal side.

  Therefore, according to this power supply device, it can be used as an antenna switching device that automatically selects a film antenna most suitable for reception from among a plurality of film antennas.

  In this power supply apparatus, since the reception signal having a high signal level is selected and output from the selection means, the detection means and the voltage setting means may be configured in the same manner as in the sixth aspect. Alternatively, the detection unit may detect the signal level of the reception signal output from the selection unit, and the voltage setting unit may set the power supply voltage based on the detected signal level.

  However, in this power supply apparatus, the selection means needs to detect the signal level of each received signal in order to select a received signal having a high signal level. For this reason, when the detection means is shared by the selection means and the voltage setting means, the detection means and the voltage setting means are configured in the same manner as in the sixth aspect, and each reception detected by the detection means is configured. The signal level of the signal may be input to both the selection means and the voltage setting means.

  Next, since the mobile reception system according to claim 8 includes the film antenna according to claim 2 and the power supply device according to claim 3 or 4, The receiving system is suitable for receiving various types of broadcast radio waves.

  Moreover, the receiving system for mobile bodies of Claim 9 is provided with two or more film antennas of Claim 2, and these power supply apparatuses in any one of Claims 5-7 WHEREIN: From these each film antennas. Since the received signals are mixed or selected and transmitted to the terminal side, it is possible to realize a diversity type or antenna switching type receiving system suitable for receiving various broadcast radio waves in the mobile body.

Embodiments of the present invention will be described below with reference to the drawings.
In the following description, FIG. 1 is a schematic configuration diagram showing the overall configuration of a mobile receiver system to which the present invention is applied, and FIG. 2 shows the appearance of a film antenna used in the receiver system of this embodiment. FIG. 3 is an explanatory diagram for explaining details of the film antenna, and FIG. 4 is a block diagram showing a circuit configuration of a mixer used in the receiving system of the present embodiment.

  As shown in FIG. 1, the mobile reception system according to the present embodiment is attached to, for example, an upper part and a lower part of an automobile windshield, and receives television broadcast waves (UHF broadcast) such as terrestrial digital broadcasts. A diversity system receiving system that includes a pair of film antennas 10 and 20, and that receives signals from the film antennas 10 and 20 are mixed by a mixer 30 and transmitted to a vehicle-mounted device (receiving device) on the terminal side. is there.

  The film antennas 10 and 20 are formed in an L shape in which the lengths of the two linear portions are substantially the same, and amplification units 12 and 22 for amplifying the received signals are provided at the corners that are the center of the L shape. It has been.

  The film antennas 10 and 20 are arranged so that the amplification units 12 and 22 are located at the end of the windshield on the passenger seat side (right side in the figure). The mixer 30 is connected via coaxial cables 14 and 24 embedded in a pillar or the like surrounding the windshield. In addition, the mixer 30 is arrange | positioned in the position hidden from windshields, such as a pillar, like the coaxial cables 14 and 24. FIG.

  Next, as shown in FIG. 2, the film antennas 10 and 20 can be attached to the windshield of an automobile by laminating a mesh-like (mesh) antenna conductor on an L-shaped transparent film 50. It is formed so as not to obstruct the occupant's view.

  2 and 3 show the configuration of the film antenna 10, the film antenna 20 is configured to be vertically symmetric with respect to the film antenna 10 when installed on the windshield 2 of an automobile. However, since the basic configuration is exactly the same as that of the film antenna 10, the drawing of the film antenna 20 is omitted.

  The transparent film 50 is composed of, for example, a substrate material made of a PET material and a coating material, and the mesh-like antenna conductor is formed on the surface of the substrate material and covered with the coating material. The antenna conductor is a conductive material laminated on a substrate material formed by, for example, etching or the like so as to have a mesh-like antenna shape to be described later, and the width of the line forming the mesh is approximately 10 μm. It has become.

  Next, the antenna conductor includes linear conductors 52a and 54a arranged in parallel to one linear part of the transparent film 50, and linear conductors 52b and 54b arranged in parallel to the other linear part. It is composed of

  The length of each of these conductors 52a, 54a, 52b, 54b is approximately one quarter (λ / 4) of the wavelength λ of the reception frequency representing the frequency band (470 MHz to 770 MHz) of the reception signal (television UHF broadcast). ), And the width of each conductor 52a, 54a, 52b, 54b is such that the conductors 52a, 52b arranged outside the L-shape in each linear portion of the transparent film 50 are inside the L-shape. It is set so as to be wider than the conductors 54a and 54b disposed in the.

  Specifically, the width of the conductors 52a and 52b is set to 15 mm, for example, and the width of the conductors 54a and 54b is set to 2 mm, for example. Further, the gap between the conductors 52a, 52b and the conductors 54a, 54b is, for example, 4 mm, and the length of each conductor 52a, 52b, 54a, 54b is, for example, 110 mm. This is because the characteristic impedance of the film antennas 10 and 20 is set to the same characteristic impedance as that of the coaxial cables 14 and 24 (for example, 75Ω).

  The conductors 52a, 54a, and 52b, 54b disposed in the respective straight portions of the transparent film 50 are connected to the open ends of the respective straight portions of the transparent film 50, and the narrow conductors. 54a and 54b are mutually connected by the center part (corner part) of L character.

  In addition, as shown to Fig.3 (a), the wide conductors 52a and 52b arrange | positioned at each linear part of the transparent film 50 are open | released by the L-shaped center part (corner part), and the open | release is carried out. At the ends, power supply terminals 53a and 53b for electrical connection with circuits in the amplification units 12 and 22 are provided.

  Further, in the connection portion of the conductor 54b to the conductor 54a and the connection portion of the conductor 52b to the conductor 54b, radio waves (radio waves having the above reception frequency) received by the conductors 54b and 52b are transmitted. Inductors 56 and 58 for delaying the phase by approximately 90 degrees are provided.

  That is, in the film antennas 10 and 20 of the present embodiment, as shown in FIG. 3B, two linear conductors having different widths are arranged substantially in parallel and both ends of each conductor are connected to each other. As a result, the basic structure is a two-wire folded dipole antenna that is set so as to match the coaxial cables 14 and 24 for communication signal transmission because the feeding point is unbalanced.

  And in this embodiment, in order to make the directivity of the film antennas 10 and 20 suitable for a moving body and substantially non-directional with no null point, the two-wire folded dipole antenna shown in FIG. Inductors 56 and 58 that are bent in an L shape around the feeding point and delay the phase of the received signal by approximately 90 degrees are formed on the antenna portion (conductors 52b and 54b) formed on one straight portion of the L shape. It is provided.

  Therefore, according to the film antennas 10 and 20 of the present embodiment, the directivity of the horizontal plane around the moving body is substantially eliminated by using it on a moving body that is as horizontal as possible in a moving body such as a windshield of an automobile. It becomes directivity, and it becomes possible to stably receive broadcast radio waves transmitted from a terrestrial broadcast station without being influenced by the traveling direction of the moving body.

  In particular, in the mobile reception system of the present embodiment, the diversity system reception system is configured by using the two film antennas 10 and 20, so that the broadcast radio waves from the broadcast station can be stabilized more stably. It will be possible to receive.

  Next, as shown in FIG. 4, the amplification units 12 and 22 amplify the reception signals received by the film antennas 10 and 20, an amplification circuit 61 as amplification means, and the reception signals from the amplification circuit 61. A power supply separation circuit 62 serving as a power supply separation unit is provided on the output path and extracts the power supply voltage transmitted from the terminal side and supplies it to the amplifier circuit 61 as a drive voltage.

  As shown in FIG. 3C, each of these circuits 61 and 62 is formed on a printed wiring board (hereinafter simply referred to as a board) 64 on which various electronic components constituting each of the circuits 61 and 62 are mounted. The amplification units 12 and 22 are provided integrally with the film antenna 10 by fixing the substrate 64 to the transparent film 50 via the adhesive layer 66.

  In addition, when the substrate 64 is fixed to the transparent film 50 through the adhesive layer 66, the reception signal input terminal 67 connected to the power supply terminals 53a and 53b of the antenna conductor and the amplified reception signal are connected. A connector 65 for connecting a coaxial cable that outputs to the outside is also provided. And this board | substrate 64 is protected by the cover 68 made from a synthetic resin surrounding the whole board | substrate with the connector 65 as a connection terminal of a coaxial cable protruding outside. In addition, FIG.3 (c) is the sectional view on the AA line shown in FIG.

  On the other hand, an adhesive is applied to the mounting surface of the transparent film 50 on the windshield 2 or the like, but peeling portions 50a and 50b to which no adhesive is applied are formed at two end portions. (See FIG. 3A). For this reason, if these peeling parts 50a and 50b are utilized, the film antennas 10 and 20 with which the windshield 2 etc. were mounted | worn can be removed easily.

  Further, the outer peripheral edge of the transparent film 50 has a windshield as shown in FIG. 3D in order to prevent a step on the glass surface when the film antennas 10 and 20 are mounted on the windshield 2 or the like. It is formed so as to incline from the mounting surface to 2 etc. to the upper surface where the antenna conductor is formed. FIG. 3D is an enlarged view of a region B indicated by a one-dot chain line in FIG.

  Next, in addition to the function as a mixer that mixes the reception signals from the film antennas 10 and 20, the mixer 30 supplies power to the amplification units 12 and 22 of the film antennas 10 and 20. As a function.

  That is, first, the mixer 30 has input terminals T1 and T2 connected to the amplification units 12 and 22 of the film antennas 10 and 20 via coaxial cables 14 and 24, and inputs to these input terminals T1 and T2. A mixing circuit 72 that mixes the received signals and an amplification circuit 76 that amplifies the reception signals mixed by the mixing circuit 72 are provided, and the reception signals amplified by the amplification circuit 76 are output terminals. It is configured to output from To to an external receiving device.

  A branch circuit 78 for branching a part of the reception signal amplified by the amplification circuit 76 is provided on the output path of the reception signal from the amplification circuit 76, and the input of the reception signal to the amplification circuit 76 is provided. On the path, an automatic gain adjustment circuit (AGC circuit) for adjusting the input level of the received signal to the amplifier circuit 76 so that the signal level of the received signal branched by the branch circuit 78 becomes a preset target level. ) 74 is provided.

  In addition, the mixer 30 is provided with a power supply circuit 80 that receives power supply from a vehicle-mounted power supply (battery) and generates a power supply voltage for driving the internal circuit of the mixer 30 and the amplification unit, and the input terminal T1, On the transmission path of the received signal from T2 to the mixing circuit 72, power supply superimposing circuits 91 and 92 for supplying a DC power supply voltage from the input terminals T1 and T2 to the amplification units 12 and 22 are provided.

  In addition, the mixer 30 supplies a power supply voltage supplied to the amplification units 12 and 22 via the power supply superimposing circuits 91 and 92 based on the power supply voltage generated by the power supply circuit 80, as a high voltage VH (for example, 8 V) and A voltage switching circuit 90 that switches to any one of the low voltages VL (for example, 5 V) is provided.

  The power supply voltage switched by the voltage switching circuit 90 is set by a determination circuit 88 that determines whether or not the signal level of the received signal from each of the film antennas 10 and 20 is higher than a predetermined determination level.

  That is, the mixer 30 includes branch circuits 81 and 82 for branching a part of the received signals from the film antennas 10 and 20 input via the input terminals T1 and T2, and the branch circuits 81 and 82. Detection circuits 83 and 84 are provided as detection means for detecting the signal level by detecting received signals from the branched film antennas 10 and 20. Then, by inputting the outputs from these detection circuits 83 and 84 to the integration circuit 86 as they are, the integration circuit 86 detects the higher voltage among the detection voltages output from the detection circuits 83 and 84. The voltage (in other words, the detection voltage of the received signal having the higher signal level) is integrated, and the integration result is input to the determination circuit 88 as voltage setting means.

  As a result, the determination circuit 88 increases the power supply voltage supplied to each amplification unit 12 and 22 in accordance with the signal level of the reception signal having the higher level among the reception signals from the two film antennas 10 and 20. / Set either low power supply voltage VH / VL.

  Specifically, when the signal level of the received signal is equal to or lower than a predetermined determination level and it is necessary to suppress noise in order to ensure the C / N of the received signal, the determination circuit 88 starts from the voltage switching circuit 90. Is set to a low voltage VL, noise generated by the amplification operation of the amplification circuit 61 in each amplification unit 12 and 22 is suppressed, and the amplification circuit 61 is operated as a low noise amplifier. Is higher than the determination level and the output level of each of the amplification units 12 and 22 needs to be increased, the output voltage from the voltage switching circuit 90 is set to the high voltage VH to power up the amplification circuit 61. Operate as an amplifier.

  The integrating circuit 86 is connected to the power supply voltage of the amplifier circuit 61 in the amplifier units 12 and 22 (in other words, the amplifier circuit 61) in accordance with the change in the signal level of the received signal input to the determination circuit 88 as voltage setting means. The operating point is to prevent frequent changes, and is configured as a low-pass filter having a predetermined time constant.

In this embodiment, the reception operation is stabilized by making the time constant of the integration circuit 86 longer than the guard interval set in the digital terrestrial broadcasting.
In other words, in the case of terrestrial digital broadcasting, in order to modulate the broadcast signal by the OFDM (Orthogonal Frequency Division Multiplexing) method, and to suppress interference due to multipath interference caused by broadcast radio waves that arrive later than the original broadcast radio waves, A guard interval is set.

  Therefore, in this embodiment, by setting the time constant of the integrating circuit 86 to be longer than the guard interval, even if the operating point of the amplifier circuit 61 in the amplifier units 12 and 22 is changed, the terminal side digital The broadcast can be received / demodulated stably.

  As described above, in the mobile receiver system of this embodiment, the characteristic impedances are matched to the coaxial cable by adjusting the widths of the conductors arranged in parallel to each other as the film antennas 10 and 20. A two-wire folded dipole antenna is used as a basic configuration, and the two-wire folded dipole antenna is made of an antenna conductor bent in an L shape using inductors 56 and 58.

  For this reason, according to the mobile reception system of the present embodiment, the directivity of each film antenna 10, 20 is made omnidirectional, and the broadcast radio waves can be stabilized without being influenced by the traveling direction of the mobile. In addition, the reception signal can be transmitted via the coaxial cable without providing a balanced-unbalanced converter at the feeding point.

  In addition, since the feeding points of the film antennas 10 and 20 are provided with amplification units 12 and 24 that amplify and output the received signals, the film antennas 10 and 20 can be used even in regions where the electric field strength of broadcast radio waves is low. The reception signal can be stably supplied from the terminal to the terminal side.

  Each amplification unit 12, 24 is supplied with power from the mixer 30, and the power supply voltage supplied to each amplification unit 12, 24 is received from each amplification unit 12, 24. Based on the signal level of the signal, the low voltage VL is set when the signal level is low, and the high voltage VH is set when the signal level is high.

  Therefore, when the electric field strength of the broadcast radio wave is low, the amplification units 12 and 24 are operated as a low noise amplifier to secure the C / N of the received signal. When the electric field strength of the broadcast radio wave is high, the amplification unit 12 and 24 can be operated as power amplifiers with high output levels to prevent distortion in the received signal.

As mentioned above, although one Embodiment of this invention was described, this invention is not limited to the said embodiment, A various aspect can be taken in the range which does not deviate from the summary of this invention.
For example, in the above embodiment, in order to be able to easily remove the film antennas 10 and 20 mounted on the windshield 2 or the like, the mounting surface of the transparent film 50 on the glass or the like in the film antennas 10 and 20. In the above description, the peeling portions 50a and 50b to which the adhesive is not applied have been formed. For example, as shown in FIG. 5 (a), instead of the peeling portions 50a and 50b at both ends of the transparent film 50, The knobs 51a and 51b to which no adhesive is applied may be provided in a protruding manner.

  Moreover, in the said embodiment, when mounting the film antennas 10 and 20 to the windshield 2 etc., in order to prevent that a glass surface makes a level | step difference, it demonstrated as what inclines the outer periphery of the transparent film 50. For example, as shown in FIGS. 5B and 5C, the outer peripheral edge of the transparent film 50 is formed so as to be rounded from the mounting surface to the windshield 2 or the like to the upper surface on which the antenna conductor is formed. Also good.

  Further, as illustrated in FIGS. 5A, 5B, and 5D, in order to improve workability when removing the film antennas 10 and 20 from the windshield 2 or the like, the amplification unit 12 is covered with a cover. 68, a bar-shaped pressing member 69 that penetrates through the substrate 64, the adhesive layer 66, and the transparent film 50 and can come into contact with a mounted portion such as the windshield 2 may be provided.

  That is, if the pressing member 69 is provided in the amplification unit 12 in this way, when the film antennas 10 and 20 are removed from the mounted portion such as the windshield 2, the pressing member 69 is pressed toward the mounted portion. By pulling up the entire amplification unit 12 in the direction opposite to the mounted portion, the portions of the film antennas 10 and 20 provided with the amplification unit 12 can be easily removed.

5B is a cross-sectional view taken along the line C-C shown in FIG. 5A, and FIG. 5C is an enlarged view of a region D indicated by a one-dot chain line in FIG. 5B.
On the other hand, in the above-described embodiment, the pair of film antennas 10 and 20 have been described as being disposed at the upper and lower positions at the passenger seat side end position of the windshield of the automobile. This is because the antenna gain can be increased by narrowing the directivity in the vertical plane by mixing the received signals from the antennas 10 and 20 with the mixer 30.

  However, the pair of film antennas 10 and 20 may be arranged at the left and right end positions above (or below) the windshield as shown in FIG. When the antennas 10 and 20 are installed in this way, as shown in FIG. 6B, a part of the vehicle enters a dead zone where radio waves do not reach due to a building such as a building, and one antenna Even if it becomes impossible to receive radio waves, it may be possible to receive with the other antenna, and the radio wave reception rate (reception possibility) in an automobile can be increased.

  As shown in FIG. 1 or FIG. 6 (a), when the film antennas 10 and 20 are mounted on the windshield, the power feeding section (in other words, the amplification unit 22) is arranged at the end of the windshield as much as possible. Thus, it is desirable not to obstruct the occupant's view.

  In the above embodiment, the reception signals from the film antennas 10 and 20 are mixed by the mixer 30 having a function as a power supply device and output to the terminal side. 7 is provided, and an antenna switching device 40 shown in FIG. 7 is provided, and among the received signals from the film antennas 10 and 20, the signal level is higher (in other words, the C / N (carrier-to-noise ratio) is larger). May be selected and output to the terminal side.

  The antenna switcher 40 is provided with a switch 94 that selects one of the received signals input to the input terminals T1 and T2 and outputs the selected signal to the AGC circuit 74 instead of the mixing circuit 72. Further, the control circuit 96 4 and the addition circuit 98 are added to the mixer 30 shown in FIG.

  That is, in the antenna switch 40, the detection voltage output from the detection circuits 83 and 84 is input to the control circuit 96 and the addition circuit 98. Then, the control circuit 96 compares the two detection voltages and switches the switch 94 so that the reception signal having the higher detection voltage (that is, the signal level higher) passes to the terminal side. Further, the adder circuit 98 adds the detection voltages so as not to affect the voltage levels of the detection voltages input to the control circuit 96 and inputs them to the integration circuit 86.

  Accordingly, a reception signal having a high signal level and a high C / N is selectively output from the antenna switch 40 to the terminal side, among the received signals from the film antennas 10 and 20, and the antenna switch 40 is It functions also as the power supply device of the present invention, and can supply an appropriate level of power supply voltage to each of the film antennas 10 and 20.

  In the above embodiment, the battery voltage is directly supplied to the mixer 30. However, as shown in FIG. 8, transmission of a received signal from the output terminal To to the receiving device 100 on the terminal side is performed. A power supply superimposing device 110 that superimposes the battery voltage is provided on the path (coaxial cable), and a power supply separation filter 79 is provided on the output path of the received signal from the amplifier circuit 76 to the output terminal To in the mixer 30. The battery voltage supplied from the power supply superimposing device 110 may be separated and input to the power supply circuit 80.

  On the other hand, in the above embodiment, the diversity type reception system including the two film antennas 10 and 20 has been described. However, the present invention may be a reception system including one film antenna or the film antenna. Even a receiving system including three or more can be applied in the same manner as in the above embodiment.

  In the above embodiment, the antenna conductors of the film antennas 10 and 20 are bent in an L shape, and the two inductors 56 and 58 are used to make the directivity characteristic omnidirectional. The number of inductors may be set as appropriate according to the required antenna characteristics, and capacitors may be used instead of inductors.

It is a schematic block diagram showing the structure of the whole mobile receiver system of embodiment. It is an external view showing the external appearance of a film antenna. It is explanatory drawing explaining the detailed structure of a film antenna. It is a block diagram showing the circuit structure of a mixer. It is explanatory drawing explaining the modification of a film antenna. It is explanatory drawing explaining the modification of arrangement | positioning of a film antenna. It is a block diagram showing the circuit structure of an antenna switch. It is explanatory drawing showing the structural example in the case of supplying a battery voltage to a mixer via a power supply superimposition apparatus.

Explanation of symbols

  2 ... windshield, 10 ... film antenna, 12, 22 ... amplification unit, 14, 24 ... coaxial cable, 20 ... film antenna, 30 ... mixer, 40 ... antenna switch, 50 ... transparent film, 50a, 50b ... peeling 51a, 51b ... knob, 52a, 52b, 54a, 54b ... conductor, 53a, 53b ... feeding terminal, 56, 58 ... inductor, 61 ... amplification circuit, 62 ... power supply separation circuit, 64 ... substrate, 65 ... Connector, 66 ... Adhesive layer, 67 ... Terminal, 68 ... Cover, 69 ... Pressing member, 72 ... Mixing circuit, 74 ... AGC circuit (automatic gain adjustment circuit), 76 ... Amplifying circuit, 78 ... Branch circuit, 80 ... Power supply circuit , 81, 82 ... branch circuit, 83, 84 ... detection circuit, 86 ... integration circuit, 88 ... determination circuit, 90 ... voltage switching circuit, 91, 92 ... power supply superposition circuit, 94 ... Pitch, 96 ... control circuit, 98 ... adding circuit, 100 ... receiving device, 110 ... power line device, T1, T2 ... input terminal, the To ... output terminal.

Claims (9)

A film antenna formed by laminating an antenna conductor on a film having electrical insulation,
The antenna conductor is
Two conductors with different widths are arranged in parallel and connected to each other at both ends so that the characteristic impedance is set to match the coaxial cable for communication signal transmission. A dipole antenna,
For the film, the entire antenna conductor is bent in an L shape with the feeding point as the center, and an antenna portion that forms one straight portion of the L shape is compared with an antenna portion that forms the other straight portion. A film antenna, characterized in that the film antennas are stacked in a state where phase-shifting means for shifting the phase of a communication signal by approximately 90 degrees is disposed. In the film antenna,
A connection terminal to which the coaxial cable can be connected;
Amplifying means for amplifying a reception signal from the antenna conductor and outputting the amplified signal to the connection terminal;
A power supply separation means for extracting a power supply voltage input to the connection terminal from the outside and supplying the amplification means;
The film antenna according to claim 1, wherein an amplification unit including: A power supply device that supplies power to the amplification unit of the film antenna according to claim 2 via a coaxial cable,
Detecting means for detecting a signal level of a received signal transmitted from the film antenna via the coaxial cable;
The amplification unit determines whether the signal level detected by the detection means is higher than a determination level, so that the voltage is high when the signal level is high and the voltage is low when the signal level is low. Voltage setting means for setting the power supply voltage to be supplied to
A power supply device comprising:   4. An amplification circuit with an automatic gain adjustment circuit for amplifying a reception signal transmitted from the film antenna via the coaxial cable to a predetermined target level and outputting the amplified signal to a terminal side. The power supply device described in 1.   A plurality of input terminals for respectively receiving reception signals from a plurality of film antennas via the coaxial cable, and a mixing circuit for mixing the reception signals input to the plurality of input terminals. The power supply device according to claim 3 or 4.   The detection means detects the signal level of the received signal input to each input terminal, and the voltage setting means is based on the highest signal level among the signal levels detected by the detection means. The power supply apparatus according to claim 5, wherein the power supply voltage is set.   A plurality of input terminals for inputting reception signals from a plurality of film antennas via the coaxial cable, and a reception signal having a high signal level among the reception signals input to the plurality of input terminals to the terminal side The power supply device according to claim 3, further comprising: a selection circuit that selects the output signal as a signal.   A mobile antenna receiving system comprising the film antenna according to claim 2 and the power supply device according to claim 3 or 4.   A plurality of film antennas according to claim 2 and a power supply device according to any one of claims 5 to 7 are provided.

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