JPH0524104Y2 - - Google Patents

Description

[Detailed description of the invention] "Purpose of the invention" (Field of industrial application) The present invention relates to relay protection circuits, and is particularly concerned with damage to the relay itself and other damage caused by improper switching of connected relays by external signals. This invention relates to a protection circuit that can prevent adverse effects on a system.

(Prior art) In general, power switching relays are set so that when the contacts are in a normal pressure-contact state, the desired power-withstanding performance is obtained, and the contacts are unlikely to melt or wear out, but when energized, It is known that when the contacts are switched, the instantaneous contact pressure decreases, causing significant melting and wear of the contacts.

However, in general electronic equipment with a built-in relay, the above-mentioned disadvantages are not taken into consideration, and the relay can be switched arbitrarily even when the power is on. For example, in the antenna matching device shown in Fig. 3, the relay can be switched at will. Whether the power output from the transmitter/receiver 20 is supplied directly to the antenna ANT or via the coupler circuit 21 is selectively switched by the relay RL using an external changeover switch SW, but it is completely optional even during transmission. Since switching is possible, the above-mentioned contacts are subject to severe melting and wear, which is a serious problem, especially for antenna matching devices that handle high-frequency power.

Conventionally, this problem has been solved by using a large-capacity type relay RL, but a high-power type relay is large and expensive, which inevitably increases the cost of the entire device.

It goes without saying that switching the relay while it is energized as described above not only melts and wears out the relay itself, but also adversely affects other systems.

(Problem to be solved by the invention) In general, in antenna switching relays that use antenna matching devices or not, such as the above-mentioned wireless communication equipment, relay switching is performed only after transmission is complete or when power is not being supplied. In many cases, it is sufficient to perform this during reception, so in this invention, the on/off state of the power source is detected, and when the detection signal is on, relay switching is set by external operation etc. It is an object of the present invention to provide a circuit that protects the relay by automatically reserving this and maintaining the relay connection state before switching.

"Structure of the invention" The relay protection circuit according to the invention controls multiple paths provided in the power transmission system using an external signal in a high frequency power transmission system where passing power is intermittent, such as a wireless communication transmission system. A relay protection circuit for a wireless device configured to select and switch a relay using a relay, which includes a detection means for detecting that the wireless device is in a transmitting state, and a detection signal from the detection signal is turned on. In some cases, a relay operating state holding means is provided for holding off switching of the relay connection by an external signal.

(Function) In a wireless device in which a plurality of paths provided in the power transmission system are selectively switched by a relay controlled by an external signal, detecting means indicates that the wireless device is in a transmitting state. If this is detected, even if a relay connection switching setting is made by an external signal, this setting is automatically reserved, the initial relay connection state is maintained, and no switching occurs.

On the other hand, when the wireless device is switched from the transmitting state to the receiving state, the relay is switched to the set state by an external signal.

For this reason, when the wireless device is in a transmitting state, the relay is protected from being applied with a large amount of power, and the relay does not melt or wear out, so the capacity of the relay can be minimized.

(Example) An example of the relay protection circuit according to the present invention will be described based on FIGS. 1 and 2.

The relay protection circuit of the present invention is used in a power transmission system 1 in which passing power is intermittent, such as a wireless communication transmission system, in which multiple paths 3 are provided in the power transmission system 1.
This is a relay protection circuit for a wireless device in which the signals a and 3b are selectively switched by a relay 3, and basically consists of a detecting means 5 for detecting that the wireless device is in a transmitting state, and the detecting means. When the signal from 5 is on, relay operation state holding means 4 is provided to reserve switching of the relay connection by an external signal.

To explain the above configuration in detail, in the embodiment, the power transmission system 1 includes a transmitter/receiver 2 as a power source and an antenna ANT.
is shown as a line, and the transceiver 2 has an output terminal T that outputs a high level (H) signal only when in a transmitting state. The system line 3a in the power transmission system 1 is shown as a direct line, and the system line 3b is shown as an antenna coupler AC.
It is shown as a line with an intervening line. The detection means 5 is shown as a detection terminal TV for detecting whether the transceiver 2 is in a receiving state or a transmitting state, and a signal from this detection terminal TV is transmitted to the relay operating state holding means 4. is input.
A signal from a switch S for selecting the plurality of paths 3a and 3b is also input to this relay operating state holding means 4, and the switch S
only when selects the path 3b side, the input terminal SV
The configuration is such that a high level (H) signal is input to the input terminal.

The relay operating state holding means 4 includes transistors Q ₁ to Q ₄ , diodes, and Zener diodes.
Dz, resistor _R1 , coil part RL of relay 3, etc. as shown in the figure.To explain an example of its operation, resistor _R1 has a voltage lower than the operating voltage of coil part RL, and transistor Q The voltage that can turn _on the Zener diode Dz
It is now applied by

Furthermore, if the Zener voltage is Vz, Vz must be equal to or less than 1.2 V, obtained by subtracting the VCE (0.6 V) of transistor _Q3 plus the VBE (0.6 V) of transistor _Q2 from the power supply voltage VR, or Vz≦VR-1.2.

Figure 2 shows the relationship between the on/off states or potential levels of the input terminal SV, the detection terminal TV, the transistors Q ₁ to _{Q 4} , and the coil section RL, and shows the initial state model.
FIG. 6 is a transition diagram when the input state is sequentially changed from _P1 . In addition, the symbols "↑H" and "↓L" in the figure are
Each indicates that the transition is switched from L to H and from H to L at the time of transition switching.

Model _P1 is an initial state model in which both the input end SV and the detection end TV are at low level (L), that is, the transmitter/receiver 2 is in the receiving state and the antenna coupler AC is not inserted. Transistors Q ₁ ~ _{Q 4}
are all off, so the coil section of relay 3
RL is also off.

Model P ₂ is a model in which an antenna coupler AC is inserted in the receiving state. That is, the input terminal SV becomes (H), the transistor _Q1 is turned on, the coil section RL of the relay 3 is turned on, and the antenna coupler AC is inserted. Also, the detection end
Since TV remains (L), transistor Q ₂ ,
Q ₃ and Q ₄ remain off.

Model P ₃ is a model when the transceiver 2 is switched from the state P ₂ to the transmitting state. Transistor Q ₄ turns on, but since transistor Q ₁ is on, transistor Q ₂ remains off, so transistor Q ₃ cannot turn on either. Therefore, the coil portion RL of the relay 3 is kept in the on state.

Model P ₄ has antenna coupler in transmitting state
This is an operation model in which AC is disconnected to make it pass, but even if you try to turn off transistor Q ₁ by setting the input terminal SV to (L), transistor Q ₄
is on because the sensing terminal is at the base of transistor _Q1
(H) from the TV is input, transistor _Q1 remains on, and antenna coupler AC remains inserted.

In model P ₅ , the input terminal SV remains unchanged at P ₄ and the detection terminal TV is set to (L) in the receiving state, and transistor Q ₄ is turned off, so transistor Q ₁
The base voltage disappears and the coil turns off.
RL turns off and returns to the same state as _P1 .

Model P ₆ is set to the transmitting state after returning to the initial state in P ₅ , and transistors Q ₃ and Q ₂ are turned on due to the addition of (H) from the detection end TV.
Transistor _Q4 remains off because the voltage from power supply VR is applied to its base, and no voltage is applied to the base of transistor _Q1 . In other words, the coil portion RL does not operate.

Model P ₇ has an antenna coupler AC during transmission
In this state, the input terminal SV is set to (H) in order to insert the transistor Q 2 , but since the transistors Q ₂ and Q ₃ are turned on, no voltage is applied to the base of the transistor Q ₁ . Therefore, transistor _Q1 will not turn on and the antenna coupler AC cannot be inserted.

Model P ₈ switches from the transmitting state to the receiving state with the input terminal SV in the insertion position in P ₇ , and then the detecting terminal
When TV is set to (L), transistors Q ₃ and Q ₂
is turned off, the (H) level voltage of the input terminal SV is applied to the base of transistor _Q1 , transistor _Q1 is turned on, and antenna coupler AC
is inserted.

As is clear from the above operation example, the transceiver 2
When is in the transmitting state, even if the switch S is switched, the operating state of the coil section RL, that is, the relay 3, is not switched, and the relay 3 is protected. On the other hand, when the transceiver 2 is in the receiving state, the relay 3 operates in conjunction with the switching of the switch S, but since the relay 3 is not in the state of intermittent power, there is no problem.

"Effect of the invention" According to the relay protection circuit according to the invention, if the detection means detects that the wireless device is in the transmitting state, even if the relay connection switching is set by an external signal. This is automatically reserved to maintain the initial relay connection state, and on the other hand, when the wireless device is not in the transmitting state, the relay can be switched to the set state, preventing the relay contacts from melting or being worn out. There isn't. Therefore, the standard of the relay can be reduced to the necessary minimum, and it is possible to reduce the size and cost of the device.

Furthermore, since the reliability of the contacts is improved, it is particularly suitable as a relay protection circuit for devices that switch high frequency power, such as antenna matching devices in wireless communication transmission systems.

[Brief explanation of drawings]

1 and 2 show an embodiment of the relay protection circuit according to the present invention, FIG. 1 is a basic circuit diagram, and FIG.
The figure is a chart showing the voltage relationship of each part in the circuit configuration of FIG. 1. FIG. 3 is a circuit diagram showing a relay circuit in a conventional wireless communication device. DESCRIPTION OF SYMBOLS 1...Power transmission system, 2...Transmitter/receiver, 3...Relay, 4...Relay operating state holding means, 5...Detection means.

Claims (1)

[Claims for Utility Model Registration] In a high-frequency power transmission system where passing power is intermittent, such as a wireless communication transmission system, multiple paths provided in the power transmission system are selectively switched by a relay controlled by an external signal. A relay protection circuit for a wireless device configured to transmit data, comprising a detection means for detecting that the wireless device is in a transmitting state, and a detection signal from an external signal when the detection signal from the detection means is on. 1. A relay protection circuit comprising a relay operating state holding means for retaining switching of relay connection.