JP6155634B2 - Receiving machine - Google Patents

Description

  The present invention relates to a receiver, and more particularly to a technique for removing noise from broadcast radio waves received by a receiving antenna.

  Various techniques for removing noise from radio waves received by a receiving antenna of a receiver are known. For example, Patent Document 1 includes a power line noise detection circuit that detects noise voltage fluctuation (hereinafter simply referred to as noise) in a power line, and removes noise detected by the power line noise detection circuit from a radio wave received by an antenna by a noise canceller. Techniques to do this are disclosed.

  In addition, Patent Document 1 also discloses a technique for removing noise generated by a plurality of electrical components disposed around a receiver. Specifically, when a plurality of electrical components arranged around the receiver is energized, a receiving circuit that receives a notification of energization from each electrical component is provided. In addition, a noise environment evaluation circuit including a weighting circuit and a voltage signal generation circuit is provided. In the weighting circuit, the weighting is determined according to the electrical component that has received the notification that the receiving circuit is energized, and the voltage signal generation circuit generates a voltage signal corresponding to the weighting. This voltage signal is removed from the radio wave received by the antenna as noise generated by the current electrical component.

Japanese Patent No. 4177437

  In the technology of Patent Document 1, since it is necessary for the receiving circuit to receive a notification of energization from each electric component, it is necessary to connect the electric component and the receiving circuit with a wire harness, and the cost is increased due to an increase in the number of wire harnesses. turn into.

  In addition, since it is necessary to perform weighting processing by the weighting addition circuit of the noise environment evaluation circuit, there is also a problem that the processing load is high.

  In addition, the voltage signal generated by the voltage signal generation circuit of the noise environment evaluation circuit reflects only whether each electrical component is energized or not, but in reality, it is generated while each electrical component is energized. The noise you do is not always the same. Therefore, there is a possibility that the technique of Patent Document 1 cannot sufficiently remove noise.

  Patent Document 1 also discloses a technique for detecting noise by a noise detection circuit for a power supply line. As with the power supply line, a noise detection circuit may be provided for the electrical component. However, if a noise detection circuit is provided for each electrical component, the cost becomes very high.

  The present invention has been made based on this situation, and the object of the present invention is to reduce the noise of the frequency selected by the user while reducing the number of devices for noise removal. An object of the present invention is to provide an in-vehicle receiver that can be removed more easily by a simple process regardless of fluctuations in height.

In order to achieve the object, the present invention includes a receiving antenna (10) that is mounted on a vehicle and receives broadcast radio waves coming from outside the vehicle, and a tuning unit (12) that is operated when a user performs a tuning operation. , A separate conductor (21) for generating a predetermined stray capacitance between the ground plane and the conductor portion of the vehicle body of the vehicle, and one end of the receiver (1). The impedance between the vehicle body and the ground plane at the frequency of the variable coil (23) connected to the conductor portion of the vehicle body and the other end connected to the remote conductor and the broadcasting station selected by the channel selection unit. An inductance adjustment unit (22) that adjusts the value of the inductance of the variable coil so that the size of the variable coil is reduced. Indah And adjusting the the chest to inductance corresponding to the frequency that is tuned.

  In the above configuration, since the impedance between the vehicle body and the ground becomes smaller than the case where the present invention is not applied with respect to the frequency selected by the channel selection unit, it exists at the frequency among the noise received by the receiving antenna. Noise tends to be bypassed to the ground.

  The noise bypassed to the ground plane is a combination of various noises. Therefore, it is not necessary to receive a notification of energization from each electrical component arranged around the receiver by the receiving circuit and to detect noise generated by each electrical component by the noise detection circuit. Therefore, it is possible to reduce the number of devices for noise removal.

  The noise bypassed to the ground is a combination of noise from various noise sources, and the amount removed from the signal received by the receiving antenna according to the number of noise sources and the magnitude of the noise. Since the configuration is not controlled, noise can be released to the ground regardless of noise fluctuation. Furthermore, since noise can be removed by the same process regardless of the number of noise sources, the process for removing noise becomes a simple process.

It is a block diagram which shows the structure of the radio receiver 1 of this invention. FIG. 3 is a diagram illustrating the configuration and arrangement of an inductance adjusting unit 20. It is sectional drawing by the III-III line in FIG. It is a figure which shows the path | route through which noise flows as an equivalent circuit. It is a figure which shows the path | route through which noise flows as an equivalent circuit. It is a block diagram which shows the structure of the radio receiver 1 of a modification. It is a figure which shows the other example of arrangement | positioning of the metal plate. It is a figure which shows the other example of arrangement | positioning of the metal plate. It is a figure which shows the other example of arrangement | positioning of the metal plate.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. FIG. 1 is a block diagram showing a configuration of a radio receiver 1 having a function as a receiver of the present invention. The radio receiver 1 is mounted on a vehicle, and as shown in FIG. 1, as a general radio receiver such as a broadcast wave antenna 10, a high frequency amplification unit 11, a tuning unit 12, a local transmission unit 13, and a mixer unit 14. In addition to the above function, an inductance adjusting unit 20 is provided. The broadcast wave antenna 10 is an antenna installed in a vehicle in order to receive a broadcast wave (radio radio wave) transmitted from a radio broadcast station outside the vehicle and reaching the vehicle. Therefore, it is installed at a position where it is easy to receive broadcast waves. As a specific installation position of the broadcast wave antenna 10, for example, there is an upper surface or a side surface of the vehicle body 30. The broadcast wave antenna 10 corresponds to the receiving antenna described in the claims.

  The high frequency amplifier 11 amplifies the signal received by the broadcast wave antenna 10 and outputs the amplified signal to the mixer unit 14. The channel selection unit 12 is a part that is operated when the user performs a channel selection operation. By operating the channel selection unit 12, the user designates the frequency used by the broadcast station desired by the user from the radio waves of various frequencies received by the broadcast wave antenna 10, and the broadcast is performed by the processing described later. You can listen to broadcasts from stations through speakers (not shown).

  The local oscillation unit 13 oscillates a signal having a frequency selected by the user at the channel selection unit 12. Then, the oscillated signal is output to the mixer unit 14. The mixer unit 14 mixes the reception signal amplified by the high frequency amplification unit 11 and the signal generated by the local oscillation unit 13. Thus, the received signal is frequency-converted from a broadcast frequency signal to an intermediate frequency signal.

  The post-stage signal processing unit 15 further performs various types of signal processing on the intermediate frequency signal frequency-converted by the mixer unit 14, converts the electrical signal into an audio signal, and outputs it. For example, the post-stage signal processing unit 15 includes an intermediate frequency amplification unit that amplifies an intermediate frequency signal, a detection unit that detects an intermediate frequency signal after amplification, a speaker, and the like (all not shown).

  Next, the inductance adjusting unit 20 that is a feature of the present invention will be described. As shown in FIG. 3, which is a sectional view taken along line III-III in FIG. 2 and FIG. 2, the inductance adjusting unit 20 includes a metal plate 21, a variable coil adjusting circuit 22, and a variable coil 23. As shown in FIG. 3, the metal plate 21 of the present embodiment is supported by the insulating member 24 on the lower surface of the bottom 31 of the vehicle body 30 so as to face the ground plane 40. The shape of the metal plate 21 may be appropriately designed, and in the present embodiment, as an example, it is a flat plate shape having a length of 20 mm and a width of 1750 mm. One end of the variable coil 23 is connected to the bottom 31 of the vehicle body 30, and the other end is connected to the metal plate 21. That is, the metal plate 21 and the vehicle body 30 are electrically connected via the variable coil 23 only. In addition, this metal plate 21 is corresponded to the isolation conductor as described in a claim. The vehicle body 30 is made of metal (that is, a conductor).

  The variable coil adjustment circuit 22 acquires the frequency f selected by the channel selection unit 12 from the channel selection unit 12, and the impedance between the vehicle and the ground becomes 0 based on the frequency f and various capacitance values described later. Inductance (La) is calculated. Then, adjustment is made so that the inductance L of the variable coil 23 becomes the calculated La. As a method of adjusting the inductance L of the variable coil 23, for example, a motor (not shown) that changes the density of the winding portion by pressing or extending the variable coil 23 is arranged and rotated by the amount of rotation that becomes the inductance La. Just do it.

  Next, it will be described with reference to FIG. 4A and FIG. 4B that the influence of noise is reduced by adjusting the inductance L of the variable coil 23. FIG. 4B is the same circuit as FIG. 4A, but is a circuit that shows the voltages applied to the vehicle body 30, the broadcast wave antenna 10, and the metal plate 21 more easily.

  4A and 4B, Cg represents the stray capacitance between the bottom 31 of the vehicle body 30 and the ground plane 40. Ca represents a capacitance between the vehicle body 30 and the broadcast wave antenna 10, and Cb represents a capacitance between the broadcast wave antenna 10 and the ground plane 40. Cd represents the capacitance between the metal plate 21 and the ground plane 40, and Ce represents the capacitance between the vehicle body 30 and the metal plate 21. The values of Ca, Cb, Cd, and Ce may be measured and grasped in advance, for example, at the time of designing or manufacturing.

  Vn is a noise voltage that is induced by various electrical components mounted on the vehicle and electromagnetic waves from the outside and applied to the bottom 31 of the vehicle body 30 and the ground plane 40 by the capacitance Cg. A part of the noise voltage Vn is received by the broadcast wave antenna 10. That is, Va indicates a noise voltage applied to the broadcast wave antenna 10 in Vn. The noise voltages Vn and Va are generated by various devices mounted on the vehicle or electromagnetic waves coming from the outside, and noise signals having various frequencies are superimposed on each other.

As can be seen from the equivalent circuits of FIGS. 4A and 4B, the noise voltage Vn induced in the vehicle body 30 is received by the broadcast wave antenna 10 by the divided voltage of the capacitance Ca and the capacitance Cb. The magnitude of the impedance Z (ω) between the vehicle body 30 and the ground plane 40 in FIG. Note that ω is an angular velocity at the frequency f.

  Here, when the numerator in Equation 1 is 0, the impedance Z (ω) of the equivalent circuit at the frequency f is 0. The value of the inductance L (= La) at that time is uniquely determined by transforming the equation so that the numerator of Equation 1 becomes 0 and obtaining L (Equation 2). Therefore, by setting the inductance L of the variable coil 23 to La at which the magnitude of the impedance Z (ω) becomes 0 as described above with respect to the frequency f selected by the radio, the signal of the frequency f is obtained. On the other hand, the vehicle body 30-the ground plane 40 is short-circuited. That is, among the noise voltage Va on which various frequency components are superimposed, the noise component of the frequency f is easily bypassed to the ground. Note that noise components of frequencies other than the frequency f may be larger than before adjustment by adjusting the inductance L of the variable coil 23. However, the local oscillating unit 13 and the mixer unit 14 output only the signal of the frequency f (including not only the radio wave received by the broadcast wave antenna 10 but also the noise voltage Va) {in other words, to the signal processing unit 15 at the subsequent stage. Is done. For this reason, even if a noise voltage other than the frequency f exists, the noise voltage other than the frequency f does not participate in the sound output from the speaker.

  Conventionally, noise voltages generated from various devices mounted on the vehicle and from outside are divided by the stray capacitance Ca between the vehicle body 30 and the broadcast wave antenna 10 and the stray capacitance Cb between the broadcast wave antenna 10 and the ground plane 40. The pressure is received by the broadcast wave antenna 10 due to the pressure. The noise component existing at the frequency f is superimposed on the radio wave signal of the frequency f selected by the channel selection unit 12 and is output from the speaker as a noise sound.

  However, in the present embodiment, the inductance L of the variable coil 23 is adjusted so that the magnitude of the impedance Z (ω) between the vehicle body 30 and the ground plane 40 with respect to the signal of the frequency f becomes zero. Since the magnitude of the impedance Z (ω) is 0, the noise component of the frequency f of the noise voltage Vn is bypassed to the ground plane 40. Along with this, the noise voltage Va induced from the vehicle body 30 to the broadcast wave antenna 10 is also reduced. On the other hand, the radio wave signal received by the broadcast wave antenna 10 is not affected by the impedance between the vehicle body 30 and the ground plane 40. Therefore, the noise component existing at the frequency f is difficult to be superimposed on the radio wave signal of the frequency f. As a result, the ratio of noise to the signal received by the broadcast wave antenna 10 (S / N ratio) is improved, and the influence on the sound output from the speaker can be reduced.

  Furthermore, since the noise voltage Vn is a combination of noises from various noise sources provided near the radio receiver, the noise can be removed by the same process regardless of the number of noise sources. Therefore, the process for removing noise is a simple process.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to the above-mentioned embodiment, The following embodiment is also contained in the technical scope of this invention, and also the summary other than the following is also included. Various modifications can be made without departing from the scope.

  For example, the inductance adjusting unit 20 includes a storage unit (27) that stores an inductance La having an impedance of 0 at the frequency f used by each radio broadcasting station in association with each frequency f. (Fig. 5). Then, every time the tuning unit 12 is operated and the frequency is changed, the inductance adjusting unit 20 adjusts the variable coil 23 so that the inductance La corresponding to the frequency f stored in the storage unit 27 is obtained.

  According to this configuration, every time the frequency is changed, it is possible to omit the process of calculating the inductance La in which the magnitude of the impedance Z (ω) at the frequency becomes zero. Therefore, the circuit of the inductance adjusting unit 20 can be simplified, and the time for calculating the inductance La when the impedance between the vehicle body 30 and the ground plane 40 is 0 with respect to the frequency f can be saved.

  In the present embodiment, the inductance L of the variable coil 23 is adjusted so that the impedance Z (ω) is zero by the impedance adjusting unit 20, but the present invention is not limited to this (that is, the impedance Z (ω) = 0). By adjusting the inductance L of the variable coil 23, the impedance Z (ω) only needs to be smaller than in the case where the present invention is not implemented. Therefore, the impedance adjustment unit 20 may be configured to determine the inductance L with which the impedance is reduced based on Equation 1 in which the impedance is obtained, and to adjust the variable coil 23 so as to have that value.

  In the above-described embodiment, the metal plate 21 is supported by the vehicle body 30 and the insulating member 24. However, the present invention is not limited to this. The metal plate 21 may be disposed so as to be electrically separated from the vehicle body 30 except for the variable coil 23. For example, the metal plate 21 may be disposed using a front bumper 33 made of resin (that is, an insulator). . In the example of FIG. 6, the metal plate 21 is disposed on the bottom surface of the bottom portion of the front bumper 33 (the portion facing the ground plane 40), and the variable coil 23 is disposed on the bottom portion 31 of the vehicle body 30. At this time, the variable coil 23 and the metal plate 21, and the variable coil 23 and the metal part of the vehicle body 30 may be connected by the lead wires 26. The variable coil 23 may be appropriately accommodated in a case (not shown) for preventing fouling.

  Moreover, as shown in FIG. 7, you may arrange | position on the upper surface of the bottom part of the front bumper 33. FIG. By doing in this way, the metal plate 21 can also reduce dirt, such as mud. Further, as shown in FIG. 8, an under cover 32 made of an insulator may be attached to the bottom 31 of the vehicle body 30, and the metal plate 21 may be disposed below the under cover 32.

  Moreover, although the above-mentioned metal plate 21 was flat plate shape, the shape of the metal plate 21 may be other shapes (for example, box shape, spherical shape, thin film shape). For example, when the metal plate 21 is disposed on the front bumper 33 as shown in FIGS. 6 and 7, the metal plate 21 may have a undulation that matches the shape of the bottom of the front bumper 33. The shape and arrangement of the metal plate 21 (and thus the separated conductor) may be appropriately designed so that the values of the capacitances Cd and Ce satisfy the conditions required for designing the receiver 1. In this embodiment, metal is used as the separation conductor, but other conductive members may be used. Note that the present invention can be applied to the receiver 1 of other broadcast waves such as TV broadcasts in addition to radio waves using analog waves and digital waves such as AM waves and FM waves. Note that the receiver 1 in the present invention appropriately includes a known configuration (for example, an amplitude limiting circuit in the case of FM waves) according to the signal format of the broadcast wave.

1: Radio receiver (receiver)
10: Broadcast wave antenna (receiving antenna)
12: Channel selection unit 20: Inductance adjustment unit 21: Metal plate (separate conductor)
22: Variable coil adjustment circuit 23: Variable coil 27: Storage unit 30: Vehicle body 31: Bottom of vehicle body 30 (conductor portion)
32: Undercover 33: Front bumper 40: Ground

Claims (6)

A receiving antenna (10) mounted on a vehicle for receiving broadcast radio waves coming from outside the vehicle;
A receiver (1) including a channel selection unit (12) operated when a user performs a channel selection operation,
Separating conductors (21) each creating a predetermined stray capacitance between the ground plane and the conductor portion of the vehicle body of the vehicle;
A variable coil (23) having one end connected to a conductor portion of the vehicle body and the other end connected to the remote conductor;
Inductance adjustment unit (22) for adjusting the value of the inductance of the variable coil so that the magnitude of the impedance between the vehicle body and the ground plane becomes small at the frequency of the broadcasting station selected by the channel selection unit. And comprising
The inductance adjusting unit adjusts the inductance of the variable coil to an inductance corresponding to the selected frequency every time the selected frequency is changed. In claim 1,
The receiver is a receiver that receives broadcast radio waves from a plurality of broadcast stations,
The inductance adjustment unit includes a storage unit (27) that stores the value of the inductance of the variable coil, in which the magnitude of the impedance is 0 at the frequency used by each broadcasting station, in association with the frequency.
The inductance adjusting unit adjusts the inductance of the variable coil so that the inductance value corresponding to the frequency of the broadcasting station selected by the channel selection unit is the inductance value stored in the storage unit. A receiver characterized by that. In claim 1 or 2,
The receiver according to claim 1, wherein the remote conductor is supported on a bottom portion of the vehicle body by an insulating member. In any one of Claim 1 to 3,
The receiver according to claim 1, wherein the separation conductor is provided at a bottom portion of a bumper made of an insulating member of the vehicle. In any one of Claims 1-4,
The receiver according to claim 1, wherein the remote conductor has a flat plate shape. In any one of Claim 1 to 5,
The receiver, wherein the remote conductor is a metal.

Images