JP2009094670A - Receiver, pair of planar antennas, and noise canceling method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To properly remove noise superposed on signals of a receiving system without increasing scale of a receiving circuit. <P>SOLUTION: A first antenna 21 is provided, with its receiving direction set outward, on a casing 5 of a portable navigation apparatus 1 used vertically. Moreover, a second antenna 23 is provided, with its receiving direction set inward of the casing 5, at the rear surface side of the first antenna 23. Noise signal superposed on the signal received by the first antenna 21 is canceled by generating a noise canceling signal for canceling the noise signal received by the second antenna 23 in a noise canceling signal generating unit 39 and then adding the noise canceling signal to the signal received by the first antenna 21. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a receiving device, a pair of planar antennas, and a noise canceling method.

  When noise is mixed in the signal of the receiving system, problems such as malfunction of the signal processing circuit and characteristic deterioration are caused. In most cases, the noise generation source is a digital circuit provided in the vicinity of the reception system. In particular, in the electronic device in which other electronic circuits are housed in the casing together with the receiving circuit, this noise problem is important.

Various techniques relating to noise removal have been developed. A typical and basic example is a technique of providing a filter circuit. For example, Patent Document 1 discloses a technique for removing noise superimposed on a power supply voltage of a power supply line by using a low-pass filter arranged between the power supply and the ground.
JP-A-6-188729

  Therefore, even when there is a noise source in the vicinity of the reception system, it is conceivable to apply the technique disclosed in Patent Document 1 to remove noise mixed in the signal of the reception system. However, in order to completely remove high-frequency noise, it is necessary to construct a filter using a capacitor having a large capacity, which causes problems in terms of increase in component cost and module size. For example, when a 40 μF capacitor is formed on a substrate, a circuit area of 1 to 2 mm square is required only with the capacitor.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to appropriately remove noise mixed in a signal of a reception system without increasing the circuit scale of the reception circuit. It is in.

  According to a first aspect of the present invention for solving the above-described problems, a first antenna provided on a peripheral portion of a casing in which an electronic circuit is disposed with a reception direction facing outward, and the first antenna A second antenna provided on the back side of the antenna with the receiving direction in the inward direction of the casing, and a noise signal generated in the casing from a signal received by the second antenna A noise canceling signal generator for generating a noise canceling signal for canceling a noise signal mixed in the signal received by the first antenna, and the signal received by the first antenna The reception apparatus cancels the noise signal by adding the generated noise cancellation signals.

  According to the first aspect of the invention, the first antenna is provided on the peripheral portion of the housing in which the electronic circuit is disposed with the reception direction facing outward. In addition, a second antenna is provided on the back side of the first antenna with the reception direction facing inward of the housing. Then, a noise cancellation signal for canceling the noise signal received by the second antenna is generated in the noise cancellation signal generation unit and added to the signal received by the first antenna, so that the signal is received by the first antenna. The noise signal mixed in the signal is canceled.

  Since the receiving direction of the second antenna is directed toward the inner direction of the housing in which the electronic circuit is arranged, noise having the electronic circuit as a noise source can be reliably detected. Therefore, it is possible to appropriately remove noise mixed in the signal of the reception system. In addition, the noise canceling signal generation unit and the adding unit that adds the noise canceling signal can be configured with a smaller circuit compared to the case where the same function is configured by a filter using a capacitor. Can be prevented.

  As a second invention, the second antenna in the receiver of the first invention constitutes a receiver having a reception characteristic capable of receiving a signal in the same reception band as the reception band of the first antenna. May be.

  According to the second aspect of the invention, a noise signal having the same reception band as the signal received by the first antenna is received by the second antenna.

  Further, as a third invention, the first antenna and the second antenna in the receiving device of the first or second invention may constitute a receiving device comprising the same antenna.

  According to the third invention, signals inside and outside the casing are received by the same antenna.

  As a fourth invention, in the receiving device according to any one of the first to third inventions, the first antenna is a planar antenna, and the surface direction is arranged along the peripheral surface of the casing. An apparatus may be configured.

  According to the fourth aspect of the invention, since the first antenna, which is a planar antenna, is arranged along the peripheral surface of the casing, it is possible to efficiently receive signals from the outside of the casing. .

  Further, as a fifth invention, the first antenna in the receiving device of the first to fourth inventions may constitute a receiving device which is a satellite signal receiving antenna provided in an upper part of the casing. .

  According to the fifth aspect of the invention, since the first antenna is provided at the upper part of the housing, the satellite signal can be received efficiently.

  Further, as a sixth aspect of the invention, the receiving direction of one planar antenna faces the outside of the housing in which the electronic circuit is disposed, and the receiving direction of the other planar antenna faces the inside of the housing. A pair of planar antennas disposed on the periphery of the housing with the backs of the two may be configured. Further, as a seventh invention, the one planar antenna and the other planar antenna are ground planes. A pair of planar antennas bonded back to back via each other may be configured.

  According to these sixth or seventh inventions, it is possible to realize an antenna having the same operational effects as those of the first invention described above.

  Of course, as an eighth invention, the one planar antenna and the other planar antenna in the pair of planar antennas of the sixth or seventh invention may constitute a pair of planar antennas comprising the same antenna. As a ninth invention, the one planar antenna in the pair of planar antennas of any of the sixth to eighth inventions may constitute a pair of planar antennas which are satellite signal receiving antennas.

  Further, as a tenth invention, a pair of planar antennas bonded in a back-to-back manner with the receiving directions opposite to each other, the receiving direction of one of the planar antennas faces outward of the housing in which the electronic circuit is disposed, The other planar antenna is arranged around the casing so that the receiving direction is inward of the casing, and the signal received by the other planar antenna is noise generated inside the casing. A noise cancellation signal that cancels a noise signal mixed in the signal received by the one planar antenna is regarded as a signal, and the generated noise cancellation signal is generated by the signal received by the one planar antenna. May be added to form a noise cancellation method for canceling the noise signal.

  According to the tenth aspect of the invention, a noise cancellation signal for canceling the noise signal received by the planar antenna arranged so that the reception direction faces inward of the housing in which the electronic circuit is arranged is generated, The noise signal mixed in the signal is canceled by adding to the signal received by the planar antenna arranged so that the receiving direction faces the outside of the housing. Also in this case, the same effect as the first invention described above is exhibited.

  DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments in the case where the present invention is applied to a portable navigation device which is a kind of electronic equipment provided with a GPS (Global Positioning System) satellite signal receiver will be described below with reference to the drawings. However, embodiments to which the present invention is applicable are not limited to this.

1. Schematic Configuration FIG. 1 is a schematic external view of a portable navigation device 1 according to this embodiment. The directions in the following description indicate directions from the viewpoint of the user who uses the portable navigation device 1, and each of the top, bottom, left and right toward the front side, the back side, and the top, bottom, left, and right toward FIG. These directions will be described as directions of up, down, left, and right. The direction is shown in FIG.

  The portable navigation device 1 includes an antenna unit 20 configured such that a first antenna 21 and a second antenna 23 which are planar antennas sandwich a ground plane 25 with opposite directions of directions, a touch panel 71, A touch screen 70 integrally formed with a display 73 is disposed in the housing 5. The portable navigation device 1 is a portable navigation device that is used in a posture (hereinafter referred to as “standing posture”) in which the touch screen 70 faces the user side (front side). In addition to the GPS receiving circuit, electronic circuits such as a display driving circuit unit 60 and various control circuits are mounted.

  The first antenna 21 constituting the antenna unit 20 is a microstrip planar antenna for receiving an RF signal including a GPS satellite signal transmitted from a GPS satellite, and the upper surface 5 a of the peripheral portion of the housing 5. Is arranged in the housing 5 with the receiving direction facing outward (the zenith direction). Further, the first antenna 21 is arranged so that the surface direction is along the upper surface 5 a of the housing 5.

  The GPS satellite signal is a spread spectrum modulated signal called a C / A (Coarse and Acquisition) code, and is superimposed on an L1 band carrier wave having a frequency of 1.57542 [GHz].

  The other second antenna 23 is a microstrip planar antenna for receiving a noise signal generated inside the housing 5, and the receiving direction is provided on the back side of the first antenna 21 via the ground plate 25. It is arranged toward the inward direction of the body 5. The second antenna 23 has a reception characteristic capable of receiving a signal having the same reception band as that of the first antenna 21 (= the reception band of the GPS satellite signal). Assume that the antenna 21 is the same antenna. Since the reception characteristics of the second antenna 23 are the same as those of the first antenna 21, the second antenna 23 receives a signal in the same band as the signal band received by the first antenna 21.

  The ground plane 25 is a metal plate disposed so as to be interposed between the first antenna 21 and the second antenna 23 whose directing directions (reception directions) are opposite to each other, and functions as a ground for both antennas. . In other words, it can be said that the first antenna 21 and the second antenna 23 constitute a pair of microstrip planar antennas bonded to each other back to back by the ground plane 25.

  FIG. 2 is a diagram for explaining the directivity of the first antenna 21 and the second antenna 23. The first antenna 21 and the second antenna 23 have a wide directivity that spreads radially. However, since the first antenna 21 and the second antenna 23 are bonded back to back by the ground plate 25, the directivity of the first antenna 21 is the case. 5 is strong in the outward direction, and weak in the inward direction of the housing 5. For this reason, the first antenna 21 efficiently receives a signal (= GPS satellite signal) from the outside of the housing 5 together with the fact that the antenna unit 20 is disposed on the top of the housing 5. Can do.

  On the other hand, the directivity of the second antenna 23 is strong in the inward direction of the housing 5 and weak in the outward direction of the housing 5. For this reason, the second antenna 23 can efficiently receive a signal (= noise signal) generated inside the housing 5.

2. Functional Configuration FIG. 3 is a block diagram showing a functional configuration of the portable navigation device 1. The portable navigation device 1 includes a GPS receiving unit 10, a host CPU (Central Processing Unit) 50, a display drive circuit unit 60, a touch screen 70 including a touch panel 71 and a display 73, a ROM (Read Only Memory) 80, and the like. And a RAM (Random Access Memory) 90.

  The GPS receiving unit 10 is a positioning unit that measures the current position of the portable navigation device 1 based on a GPS satellite signal received from a GPS satellite, and is a functional block corresponding to a so-called GPS receiving device. The GPS receiving unit 10 includes an antenna unit 20 configured to include a first antenna 21 and a second antenna 23, an RF (Radio Frequency) receiving circuit unit 30, and a baseband processing circuit unit 40. Composed. The RF receiving circuit unit 30 and the baseband processing circuit unit 40 can be manufactured as separate LSIs (Large Scale Integration) or can be manufactured as one chip.

  The RF receiving circuit unit 30 is a receiving circuit block for a high frequency signal (RF signal), and includes an adding unit 31, a SAW (Surface Acoustic Wave) filter 33, an LNA (Low Noise Amplifier) 35, and an RF conversion circuit unit 37. And a noise cancellation signal generation unit 39.

  The addition unit 31 is an adder that adds the noise cancellation signal generated by the noise cancellation signal generation unit 39 to the RF signal including the GPS satellite signal received by the first antenna 21. Output to the filter 33.

  The SAW filter 33 is a band pass filter (surface acoustic wave filter) that passes a predetermined frequency band component of the signal output from the adder 31, and outputs the passed signal to the LNA 35.

  The LNA 35 is a low noise amplifier that amplifies the signal that has passed through the SAW filter 33 with a predetermined amplification factor, and outputs the amplified signal to the RF conversion circuit unit 37.

  The RF conversion circuit unit 37 multiplies the signal amplified by the LNA 35 by a predetermined local oscillation signal, thereby down-converting the RF signal into an intermediate frequency signal (hereinafter referred to as an “IF (Intermediate Frequency) signal”). After the IF signal is amplified, it is converted into a digital signal by an A / D converter and output to the baseband processing circuit unit 40.

  The noise cancellation signal generation unit 39 is a circuit unit that generates a noise cancellation signal that cancels the noise signal by regarding the signal received by the second antenna 23 as a noise signal, and adds the generated noise cancellation signal. To 31.

  FIG. 4 is a diagram illustrating an example of a circuit configuration of the noise cancellation signal generation unit 39. The noise cancellation signal generation unit 39 attenuates the phase shifted by the phase of the noise signal output from the second antenna 23 by 180 degrees and the signal phase shifted by the phase shift unit 391 with a predetermined attenuation rate. And an attenuating portion 393 to be configured.

  In the GPS receiving unit 10, the RF receiving circuit unit 30 and the baseband processing circuit unit 40 are arranged at positions close to each other, so that unnecessary radiation generated from the baseband processing circuit unit 40 is generated from the first antenna 21 to the RF. The signal output to the receiving circuit unit 30 may be mixed as noise. In addition, unnecessary radiation or the like generated due to the circuit operation of an electronic circuit other than the GPS receiving unit 10 (for example, the display driving circuit unit 60) is also generated with respect to the signal output from the first antenna 21 to the RF receiving circuit unit 30. Mix as noise.

  These noise signals are received by the second antenna 23 provided on the back side of the first antenna 21 provided in the peripheral portion of the housing 5 with the reception direction directed inward of the housing 5. And output to the noise cancellation signal generation unit 39. That is, the second antenna 23 receives a noise signal that can be received by the first antenna 21 at substantially the same position as the first antenna 21 that receives the GPS satellite signal that is the original signal.

  Then, a noise cancellation signal that cancels the noise signal is generated in the noise cancellation signal generation unit 39, and added to the signal output from the first antenna 21 in the addition unit 31. For this reason, the noise superimposed on the original signal (GPS satellite signal) received by the first antenna 21 can be attenuated and removed more reliably.

  The baseband processing circuit unit 40 performs correlation processing on the IF signal output from the RF receiving circuit unit 30 to capture and extract GPS satellite signals, decodes the data, and extracts navigation messages, time information, and the like. This is a circuit unit that performs positioning calculation and the like.

  The baseband processing circuit unit 40 includes a circuit that performs correlation processing, a circuit that generates a spreading code (replica code) for correlation processing, and a circuit that decodes data, as well as the baseband processing circuit unit 40 to the RF receiving circuit unit 30. The CPU 41 is a processor that performs various arithmetic processes by comprehensively controlling each unit, and includes a ROM 43 and a RAM 45 as memories.

  The host CPU 50 is a processor that comprehensively controls each unit of the portable navigation device 1 according to various programs such as a system program stored in the ROM 80.

  The display drive circuit unit 60 is a circuit unit that controls the drive of the display 73 by generating a drive signal for driving the display 73 and outputting the generated drive signal to the display 73.

  The touch panel 71 detects the touch operation position in units of dots constituting the display 73 and outputs the detection result to the host CPU 50 based on a detection principle such as pressure-sensitive type, optical type, electrostatic type, and electromagnetic induction type. A destination is input by a user operation input on the touch panel 71.

  The display 73 is configured by an LCD (Liquid Crystal Display) or the like, and is a display device that performs various displays based on the drive signal output from the display drive circuit unit 60. A navigation screen is displayed on the display 73.

  The ROM 80 stores a system program for the host CPU 50 to control the portable navigation device 1, various programs and data for realizing a navigation function, and the like.

  The RAM 90 forms a work area for temporarily storing a system program executed by the host CPU 50, various processing programs, data being processed in various processing, processing results, and the like.

3. Effects According to the present embodiment, in the portable navigation device 1 used in the standing posture, the first antenna 21 is provided on the upper portion of the housing 5 with the reception direction directed outward. Further, the second antenna 23 is provided on the back side of the first antenna 23 with the reception direction directed inward of the housing 5. A noise cancellation signal for canceling the noise signal received by the second antenna 23 is generated in the noise cancellation signal generation unit 39 and added to the signal received by the first antenna 21, thereby The noise signal mixed in the signal received by the antenna 21 is canceled.

  Since the second antenna 23 is arranged with the reception direction directed inward of the housing 5, it is possible to reliably detect noise generated from an electronic circuit that is a noise source in the housing 5. Therefore, it is possible to appropriately remove noise mixed in the signal of the reception system. In addition, the noise canceling signal generating unit 39 and the adding unit 31 for adding the noise canceling signal can be configured with a smaller circuit compared to the case where the same function is configured by a filter using a capacitor. An increase in circuit scale can be suppressed.

4). Modified example 4-1. The present invention relates to a receiving device that receives a satellite signal, a receiving device that receives a radio signal for a mobile phone, a short distance represented by a wireless local area network (LAN) or Bluetooth (registered trademark). The present invention can be similarly applied to a receiving device that receives a radio signal for wireless communication, a receiving device for terrestrial digital broadcasting, and the like.

4-2. Electronic Device The present invention can also be applied to any electronic device provided that it is equipped with a receiving device. For example, the present invention can be similarly applied to a notebook personal computer, a mobile phone, a PDA (Personal Digital Assistant), a car navigation device, and the like.

4-3. In the above-described embodiment, the antenna unit 20 configured to include the first antenna 21 and the second antenna 23 has been described as being built in the upper portion of the housing 5. Any other position may be used as long as it is a peripheral part of the body 5. For example, it may be incorporated in the back surface or side surface of the housing 5. In this case, by arranging the first antenna 21 and the second antenna 23 so that the surface direction is along the back surface or side surface of the housing 5 (more preferably parallel), It becomes possible to efficiently receive signals inside and outside the housing 5.

  Further, although the antenna unit 20 has been described as being built in the housing 5, it may be exposed. For example, the antenna unit 20 may be disposed on the upper surface 5a of the housing 5, or an opening that fits the upper surface of the first antenna 21 is provided on the upper surface 5a of the housing 5, and the lower portion of the opening is provided. Therefore, the antenna unit 20 may be disposed so as to be fitted so as to expose the upper surface portion of the first antenna 21.

4-4. In the above-described embodiment, the case where the present invention is applied to a portable navigation device used in a standing posture has been described. However, the posture in which the touch screen 70 faces the zenith direction (hereinafter referred to as “the lying posture”). The same applies to the portable navigation device used in the above.

FIG. 5 is a schematic external view of the portable navigation device 2 used in the lying position.
The configuration of the portable navigation device 2 is substantially the same as the configuration of the portable navigation device 1, but the arrangement of the antenna unit 20 is different. That is, since the portable navigation device 2 is used in a recumbent posture with the touch screen 70 facing the zenith direction, the upper surface 5 b of the housing 5 is a surface parallel to the surface of the touch screen 70.

  Accordingly, the antenna unit 20 is disposed immediately below the upper surface 5b of the housing 5, and thus is disposed at a position different from that in FIG. In FIG. 5, the antenna unit 20 is disposed behind the touch screen 70 in the upper surface 5b. However, the antenna unit 20 may be disposed on the left side, the right side, or the front side of the hand.

4-5. Ground plate In the above-described embodiment, the first antenna 21 and the second antenna 23 are described as being bonded back to back via the ground plate 25. However, the first antenna 21 and the second antenna 23 are directly bonded back to back without using the ground plate. May be.

4-6. Noise Canceling Signal Generation Unit In the above-described embodiment, the noise canceling signal generating unit 39 is described as being incorporated in the RF receiving circuit unit 30. However, the noise canceling signal generating unit 39 is a circuit independent of the RF receiving circuit unit 30. It is good also as a part.

1 is a schematic external view of a portable navigation device used in a standing posture. An explanatory view of directivity of an antenna. The block diagram which shows the function structure of a portable navigation apparatus. The figure which shows the circuit structural example of a noise cancellation signal production | generation part. 1 is a schematic external view of a portable navigation device used in a lying position.

Explanation of symbols

1 portable navigation device, 5 housing, 10 GPS receiver,
20 antenna portion, 21 first antenna, 23 second antenna, 25 ground plane,
30 RF receiving circuit section, 31 adding section, 33 SAW filter, 35 LNA,
37 RF conversion circuit section, 39 Noise cancel signal generation section,
40 baseband processing circuit section, 41 CPU, 43 ROM, 45 RAM,
50 host CPU, 60 display drive circuit, 70 touch screen,
71 touch panel, 73 display, 80 ROM, 90 RAM

Claims (10)

A first antenna provided on the periphery of a housing in which an electronic circuit is disposed with a reception direction facing outward;
A second antenna provided on the back side of the first antenna with the receiving direction facing inward of the housing;
A signal received by the second antenna is regarded as a noise signal generated inside the housing, and a noise cancellation signal for canceling a noise signal mixed in the signal received by the first antenna is generated. A noise cancellation signal generator,
And a receiver that cancels the noise signal by adding the generated noise cancellation signal to a signal received by the first antenna.   The receiving apparatus according to claim 1, wherein the second antenna has a reception characteristic capable of receiving a signal having the same reception band as that of the first antenna.   The receiving apparatus according to claim 1, wherein the first antenna and the second antenna are the same antenna.   The receiving apparatus according to any one of claims 1 to 3, wherein the first antenna is a planar antenna, and a surface direction is disposed along a peripheral surface of the casing.   The receiving apparatus according to any one of claims 1 to 4, wherein the first antenna is a satellite signal receiving antenna provided on an upper portion of the casing.   With the receiving direction of one planar antenna facing the outside of the casing in which the electronic circuit is disposed, the receiving direction of the other planar antenna is facing the inside of the casing, and A pair of planar antennas disposed on the periphery.   The pair of planar antennas according to claim 6, wherein the one planar antenna and the other planar antenna are bonded back to back via a ground plane.   The pair of planar antennas according to claim 6 or 7, wherein the one planar antenna and the other planar antenna are the same antenna.   The pair of planar antennas according to any one of claims 6 to 8, wherein the one planar antenna is a satellite signal receiving antenna. A pair of planar antennas bonded in a back-to-back manner with the receiving directions opposite to each other, the receiving direction of one planar antenna faces the outside of the housing in which the electronic circuit is arranged, and the receiving direction of the other planar antenna is Arranged around the casing so as to face inward of the casing,
A signal received by the other planar antenna is regarded as a noise signal generated inside the housing, and a noise cancellation signal for canceling a noise signal mixed in the signal received by the one planar antenna is generated. And
Adding the generated noise cancellation signal to the signal received by the one planar antenna to cancel the noise signal;
Noise cancellation method.

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