JP4213552B2 - External antenna detection circuit, wireless device and external antenna switching circuit - Google Patents

Description

The present invention includes a state of connecting the specific configuration devices, external antenna detection circuit capable of switching between a state of connecting an external device, a wireless device and an external antenna switching circuit using the external antenna detection circuit.

  When a wireless device such as a mobile phone is installed in a vehicle, etc., an external antenna installed in the vehicle or the like is connected in place of the inherent antenna originally installed in the wireless device, or a pseudo load or measurement is performed for a test. In some cases, such devices are connected (hereinafter, these connections are referred to as external connections, and externally connected devices are referred to as external devices). In order to enable the external connection, the wireless device needs a switching means for switching the connection between the unique device and the external device. In addition, since whether or not an external connection is made is related to the operating conditions of the wireless device, a detecting means for detecting the presence or absence of the external connection is also necessary.

  FIG. 2A is a block diagram showing an example of the configuration of a wireless device using conventional switching means and detection means (hereinafter collectively referred to as an external antenna detection circuit). Of the transmission signal output from the radio unit 1 composed of the transmitter and the receiver, the DC component is cut off by the capacitor 2 and only the AC component reaches the common terminal 31 of the connector 3 with the switch function that constitutes the switching means. To do. The DC potential of the common terminal 31 is pulled up by a non-zero DC voltage Vp through resistors 4 and 5 connected in series. A detecting means is configured such that a value obtained by dividing the voltage Vp by the resistors 5 and 4 and stabilized by the capacitor 6 is monitored by a DC voltmeter 71 built in the control monitoring unit 7. The terminal 32 is connected to the ground point via the inductor 8, and its DC potential is zero. In FIG. 2A, the above configuration excluding the wireless unit 1 is surrounded by a one-dot chain line and is represented as an external antenna detection circuit 9.

  FIGS. 2B and 2C are diagrams for explaining the connection between terminals of the connector 3 with a switch function. First, as shown in FIG. 2B, when the terminal 33 is in an open state where nothing is connected, the common terminal 31 and the terminal 32 are short-circuited. Next, as shown in FIG. 2C, when a load (in this figure, the external antenna 10) is connected to the terminal 33, the common terminal 31 and the terminal 32 are in an open state. That is, the connector 3 with a switch function functions as a single pole double throw type switch.

  Therefore, when the terminal 33 of the connector 3 with the switch function is in an open state, the AC component of the transmission signal is supplied to the antenna 12 unique to the wireless device via the terminal 32 and the power supply unit 11. Here, the power feeding unit 11 has an impedance matching function with the antenna 12. Since the inductor 8 is an AC suppression element that acts as a sufficiently large impedance for the AC component, it hardly affects the AC component of the transmission signal. At this time, the common terminal 31 is short-circuited to the ground point via the terminal 32 and the inductor 7, and a value obtained by dividing the pull-up voltage Vp by the resistors 5 and 4 is applied to the DC voltmeter 71.

  On the other hand, when the external antenna 10 is connected to the terminal 33 of the connector 3 with the switch function, the AC component of the transmission signal is fed to the external antenna 10 through the terminal 33. In addition to the external antenna 10, a pseudo load or a measuring instrument may be connected to the terminal 33 for the purpose of testing. At this time, since the DC potential of the common terminal 31 is open to the terminal 32, it is pulled up to a value equal to Vp, and the voltage Vp is also applied to the DC voltmeter 71. The control monitoring unit 7 can recognize the presence / absence of an external connection depending on whether the voltage applied to the DC voltmeter 71 is a divided value of Vp or Vp itself. However, when an external connection is made, the voltage Vp applied to the common terminal 31 is also applied to the external antenna 10 and other external devices via the terminal 33, which may adversely affect these external devices.

  In addition to the above-described prior art, a proposal has been made that allows switching between an antenna unique to a wireless device and an external device without using mechanical means (see, for example, Patent Document 1). The other prior art disclosed in Patent Document 1 branches the transmission output from the radio unit, and for a specific antenna, a quarter wavelength line length, and for an external device, 4 minutes. The switching circuit is configured so that power is fed through each of the three wavelength line lengths, and the impedance of the feeding point of the specific antenna is automatically adjusted according to the presence or absence of external connection.

However, in the case of the other prior art disclosed in the above-mentioned Patent Document 1, the configuration of the external antenna detection circuit is complicated and the switching state cannot be monitored. There was a problem of being limited to a very narrow band.

  The conventional external antenna detection circuit of FIG. 2 described above has a problem in that an external device is adversely affected by application of a DC voltage for detecting the external antenna. Another conventional external antenna detection circuit described in Patent Document 1 has a problem that the circuit configuration is complicated.

  The present invention has been made to solve the above problems, and provides an external antenna detection circuit that has a simple circuit configuration and does not adversely affect an external device in detecting an external antenna, and a wireless device using the external antenna detection circuit. With the goal.

In order to achieve the above object, an external antenna detection circuit according to the present invention includes a first terminal , a second terminal, and a third terminal in an external antenna detection circuit that detects whether or not an external antenna is connected to an external device. The first terminal is short-circuited to the second terminal and the first terminal and the third terminal are open, and the external antenna is the third terminal. Switching means for switching between a first state in which the first terminal is short-circuited to the third terminal and between the first terminal and the second terminal is opened, and the switching Voltage applying means for applying a voltage to the second terminal so that the second terminal has a predetermined potential when the means is in the second state; and the potential of the second terminal is When the predetermined potential is set in advance, the external Antenna is characterized by comprising detecting means for detecting that it is connected to the third terminal.

  According to the present invention, it is possible to realize a configuration capable of detecting an external antenna with a simple circuit configuration and without adversely affecting external devices.

  Embodiments of the present invention will be described below with reference to the drawings.

  Hereinafter, Embodiment 1 of the present invention will be described with reference to FIG. FIG. 1 is a block diagram illustrating a configuration of a wireless device using the external antenna detection circuit according to the first embodiment of the present invention. Since the configurations indicated by numbers in the drawing are all the same as those in FIG. 2A, their individual descriptions are omitted. The first difference between FIG. 2A and FIG. 2A is that the inductor 8 is connected to the common terminal 31 instead of the terminal 32 of the connector 3 with the switch function, and the common terminal 31 and the grounding point are short-circuited in a DC manner. It is. The second difference is that the resistor 4 is connected to the terminal 32 instead of the common terminal 31 so that the DC potential of the terminal 32 is pulled up together with the resistor 5.

  Next, the operation of the external antenna detection circuit according to the first embodiment of the present invention will be described. First, when the terminal 33 of the connector 3 with the switch function is in an open state, the AC component of the transmission signal output from the wireless unit 1 is the capacitor 2, the common terminal 31, the terminal 32 short-circuited to the capacitor 2, and the power feeding unit. 11, power is supplied to the antenna 12. This operation is the same as that in FIG. At this time, the terminal 32 is short-circuited to the ground point via the common terminal 31 and the inductor 8, and a value obtained by dividing the pull-up voltage Vp by the resistors 5 and 4 is applied to the DC voltmeter 71. When the value obtained by dividing the pull-up voltage Vp by the resistors 5 and 4 is applied to the DC voltmeter 71, the control monitoring unit 7 does not detect that the external antenna 10 is connected to the terminal 33 of the connector 3. . As a result, this point is the same as in the case of FIG.

  On the other hand, when the external antenna 10 is connected to the terminal 33 of the connector 3 with the switch function, the AC component of the transmission signal is fed to the external antenna 10 through the terminal 33. At this time, since the DC potential of the terminal 32 is open to the common terminal 31, the DC potential is pulled up to a value equal to Vp, and Vp is also applied to the DC voltmeter 71. When the pull-up voltage Vp is applied to the DC voltmeter 71, the control monitoring unit 7 detects that the external antenna 10 is connected to the terminal 33 of the connector 3. As described above, in the control monitoring unit 7, as in the case of FIG. 2A, the voltage applied to the DC voltmeter 71 is different from that of the external antenna 10 depending on whether the voltage is a divided value of Vp or Vp itself. The presence or absence of connection can be recognized.

  Since the common terminal 31 is short-circuited to the ground point via the inductor 8, the direct-current potential is zero. For this reason, when the external antenna 10 is connected to the terminal 33, the DC potential of the terminal 33 is zero as with the terminal 31, so that a non-zero DC voltage is not applied to the external device via the terminal 33. . When the external antenna 10 is connected to the terminal 33, the DC potential of the terminal 32 is pulled up to a value equal to the pull-up voltage Vp, but the common terminal 31 and the terminal 32 are open. Therefore, the pull-up voltage Vp is not applied to the external device via the common terminal 31 and the terminal 33.

  Therefore, unlike the case of FIG. 2A, the non-zero DC voltage applied to the common terminal 31 is also applied to the external antenna 10 and other external devices via the terminal 33, thereby adversely affecting the external devices. There is no such thing.

  In the first embodiment, the DC potential at the terminal 32 is pulled up through the resistors 4 and 5, and the DC voltmeter 71 monitors the value obtained by dividing the pull-up voltage Vp by the resistors 5 and 4. . On the other hand, the resistor 4 can be omitted, and the DC potential of the terminal 32 can be pulled up only by the resistor 5 and the DC voltmeter 71 can directly monitor the potential. In this case, the potential monitored by the DC voltmeter 71 is zero when no external connection is made and Vp when the external connection is made.

  According to the first embodiment of the present invention, the external antenna detection circuit is configured to monitor the switching state through the load-side terminal 32 instead of the common terminal 31 of the connector 3 with the switch function. Even when is connected, the pull-up DC voltage can be prevented from being applied to the external device.

1 is a block diagram of a wireless device using an external antenna detection circuit according to Embodiment 1 of the present invention. (A) is a block diagram of a wireless device using a conventional external antenna detection circuit. (B) And (c) is explanatory drawing of the connection between terminals of the connector 3 with a switch function.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Radio | wireless part 2 and 6 Capacitor 3 Connector 31 with a switch function Common terminal 32, 33 Terminal 4, 5 Resistance 7 Control monitoring part 71 DC voltmeter 8 Inductor 9 External antenna detection circuit 10 External antenna 11 Feeding part 12 Antenna

Claims (11)

In the external antenna detection circuit that detects whether an external antenna is connected to an external device,
A first terminal , a second terminal, and a third terminal, wherein the first terminal is short-circuited to the second terminal and the first terminal and the third terminal are opened; In the first state, the external antenna is connected to the third terminal, the first terminal is short-circuited to the third terminal, and between the first terminal and the second terminal. Switching means for switching between the opened second state;
Voltage applying means for applying a voltage to the second terminal so that the second terminal has a predetermined potential when the switching means is in the second state;
Detecting means for detecting that the external antenna is connected to the third terminal when the potential of the second terminal is the predetermined potential set in advance; External antenna detection circuit. In the external antenna detection circuit that detects whether an external antenna is connected to an external device,
A DC blocking element having two ends and blocking a DC component of a signal input to one end;
In addition to the first terminal connected to the other end of the DC interrupting element, the first DC terminal has a second terminal and a third terminal. The first terminal is short-circuited to the second terminal and the first terminal A first state in which a space between the first terminal and the third terminal is opened; and the external antenna is connected to the third terminal, the first terminal is short-circuited to the third terminal, and Switching means for switching between a first terminal and a second state in which the second terminal is open ;
An AC suppression element having two ends, one end connected to the first terminal and the other end connected to a ground point, and suppressing an AC component of the signal;
Voltage applying means for applying a voltage to the second terminal so that the second terminal has a predetermined potential when the switching means is in the second state;
Detecting means for detecting that the external antenna is connected to the third terminal when the potential of the second terminal is the predetermined potential set in advance; External antenna detection circuit. The switching means takes the first state when the external antenna is not connected to the third terminal, and takes the second state when the external antenna is connected to the third terminal. external antenna detection circuit according to claim 1 or claim 2, characterized in that it is configured switch function connector to take.   The voltage application means pulls up the second terminal with a non-zero DC voltage via a resistance element, and the detection means includes DC voltage measurement means having an input terminal connected to the second terminal. The external antenna detection circuit according to claim 2.   The voltage application means pulls up the second terminal with a non-zero DC voltage via first and second resistance elements connected in series, and the detection means has the first and second resistances. 3. The external antenna detection circuit according to claim 2, further comprising DC voltage measuring means having an input end connected to a connection end between the elements. In a wireless device that has an antenna and wireless means and can be connected to an external antenna of an external device,
A first terminal connected to the wireless means; a second terminal connected to the antenna; and a third terminal to which the external antenna can be detachably connected, wherein the first terminal is A first state in which the first terminal and the third terminal are opened while being short-circuited to a second terminal; and the external terminal is connected to the third terminal and the first terminal Switching means for switching between a second state in which the first terminal and the second terminal are opened while the second terminal is short-circuited to the third terminal ;
Voltage applying means for applying a voltage so that the second terminal has a predetermined potential when the switching means is in the second state;
Detecting means for detecting that the external antenna is connected to the third terminal when the potential of the second terminal is the predetermined potential set in advance; Wireless equipment. In a wireless device that has an antenna and can be connected to an external antenna of an external device,
Means for outputting a signal fed to the antenna, including a direct current component and an alternating current component;
A DC blocking element having two ends, one end connected to the output end of the means for outputting, and blocking a DC component of the signal;
A first terminal connected to the other end of the DC interrupting element; a second terminal connected to the power feeding means of the antenna; and a third terminal; the first terminal serving as the second terminal; A first state in which the first terminal and the third terminal are opened while being short-circuited; and the external antenna is connected to the third terminal and the first terminal is the third terminal. Switching means for switching between a second state in which the first terminal and the second terminal are open while being short-circuited to the terminal ;
An AC suppression element having two ends, one end connected to the first terminal and the other end connected to a ground point, and suppressing an AC component of the signal;
Voltage applying means for applying a voltage to the second terminal so that the second terminal has a predetermined potential when the switching means is in the second state;
Detecting means for detecting that the external antenna is connected to the third terminal when the potential of the second terminal is the predetermined potential set in advance; Wireless equipment. The switching means takes the first state when the external antenna is not connected to the third terminal, and takes the second state when the external antenna is connected to the third terminal. the wireless device of claim 6 or claim 7, characterized in that it is configured switch function connector to take. The voltage application means pulls up the second terminal with a non-zero DC voltage via a resistance element, and the detection means includes DC voltage measurement means having an input terminal connected to the second terminal. The wireless device according to claim 7 . The voltage application means pulls up the second terminal with a non-zero DC voltage via first and second resistance elements connected in series, and the detection means has the first and second resistances. 8. The wireless device according to claim 7 , further comprising DC voltage measuring means having an input end connected to a connection end between elements. In the external antenna switching circuit that switches to the connection of the external antenna of the external device,
A first terminal, a second terminal and a third terminal, wherein the first terminal is short-circuited to the second terminal, and the first terminal and the third terminal are opened 1 state, the external antenna is connected to the third terminal, the first terminal is short-circuited to the third terminal, and the first terminal and the second terminal are opened. and switching means for switching the second state,
Voltage applying means for applying a voltage to the second terminal so that the second terminal has a predetermined potential when the switching means is in the second state;
An external antenna switching circuit comprising:

Images