JPH052790B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an actuator control device used in a radio key device or the like. For example, as a radio wave key device for unlocking the doors of automobiles, etc., the applicant of the present application previously published the first
As partially shown in the figure, a doorknob 2 of a car door 1
When the touch switch 3 provided on the door is operated, a transmission request signal is transmitted from a transmitter (not shown) via the loop antenna 4 provided on the door glass, and when this signal is received by an external portable transceiver, Conversely, a device has been proposed in which this transceiver transmits a unique code, which is then sensed and compared with a predetermined code to operate an actuator for unlocking the door. However, in the case of the above device, when the loop antenna 4 on the car side and the loop antenna on the portable transmitter side are positioned almost orthogonally to each other, the sensitivity is weak due to the nature of the loop antenna. Therefore, it is necessary to increase the strength of the magnetic field radiated from the loop antenna 4. However, if a strong magnetic field is generated from the loop antenna 4, the transmission request signal can be reliably transmitted even in the above positional relationship, but on the other hand, if there are other communication devices using the same frequency band near the vehicle. In some cases, radio wave interference may occur. The present invention has been made in view of these problems, and includes a pair of antennas facing each other, an inverting circuit interposed between one of the antennas and the transmitter, and a It is an object of the present invention to solve the above-mentioned problems by making the phases of the carrier waves of the respective radiated transmission request signals to be opposite to each other. Hereinafter, the present invention will be explained based on the drawings. FIG. 2 is an external view of an automobile showing an embodiment of the actuator control device according to the present invention, and FIG. 3 is a block diagram of the same embodiment. In the figure, 5 and 6 are the left and right door glass 7 of the car,
This is a loop antenna installed at 8. 9,10
indicates a doorknob, and these doorknobs 9 and 10 are provided with touch switches 11 and 12, respectively. The left and right loop antennas 5 and 6 are the receiver 1, respectively.
3, one loop antenna 5 is directly connected to the transmitter 14, and the other loop antenna 6 is connected to the transmitter 14 via an inverting circuit 15. The output of the receiver 13 is input to a code matching circuit 16. Further, the output of the code storage circuit 17 is input to the code verification circuit 16, and when the unique code from the receiver 13 is verified with the code from the code storage circuit 17, the code verification circuit 16 outputs the output to the door lock release actuator 18. be done.
On the other hand, the outputs of the touch switches 11 and 12 attached to the left and right doorknobs 9 and 10 are supplied to a transmission/reception control circuit 19, and the output of this transmission/reception control circuit 19 is supplied to a transmitter 14 or a receiver 13. Ru. Note that 20 is a portable transceiver carried by the user of the car. Next, the operation of the above embodiment will be explained. When the touch switch 11 or 12 of either doorknob 9 or 10 is touched, an on signal is supplied to the transmission/reception control circuit 19, and this circuit 19
puts the transmitter 14 into operation. As a result, a transmission request signal is transmitted from the loop antennas 5 and 6 to the portable transceiver 20 to request transmission of a unique code. The portable transceiver 20 that has received the transmission request signal starts transmitting a signal modulated with a unique code. At this point, the transmitter 14 is already in the off state under the control of the transmission/reception control circuit 19, while the receiver 13 is in the on state, and the unique code emitted by the portable transceiver 20 is transmitted to the loop antennas 5 and 6. The signal is received by the receiver 13, demodulated by the receiver 13, and sent to the code matching circuit 16. The code matching circuit 16 matches the unique code received just now with the code registered in advance in the code storage circuit 17, and if they match, the door lock release actuator 1 is activated.
8 to release the door lock. In particular, when the transmitter 15 is in the on state, that is, when transmitting a transmission request signal to the portable transceiver 20, one loop antenna 6 is connected to the transmitter 14 via the inverting circuit 15. , the phases of the carrier waves of the transmission request signals radiated from the pair of loop antennas 5 and 6 are opposite to each other. Generally, the magnetic field H generated by a loop antenna
is on the central axis of the loop antenna, H=jILa/2λR ² (1+1/jkR)e ^-jkR (1) where I: Current flowing in the loop L: Loop length (L=2πa) λ: Signal wavelength r: Distance from the center of the loop a: Radius of the loop R: Distance from the loop (R=√ ² + ² ) k: Expressed as propagation constant. As is clear from equation (1), the magnetic field H is
There is a magnetic field component proportional to 1/R ² and a magnetic field H ~ component proportional to 1/R ³ , which can be expressed as follows. =jILa/2λR ² e ^-jkR (2) H~=ILa/2λkR ³ e ^-jkR (3) Next, the magnetic field when there is only one loop antenna
Find the ratio of magnetic field H ₁ and magnetic field H ₂ when a pair of loop antennas are placed facing each other and a current of opposite phase is applied. However, r ₀ : Spacing between two loop antennas (first loop antenna, second loop antenna) ₁ , H~ ₁ : Magnetic field (component) generated by the first loop antenna ₂ , H~ ₂ : Magnetic field generated by the second loop antenna (component) becomes. Here, in this embodiment, the door glass 7,
Since the loop antennas 5 and 6 are arranged at 8, r ₀
= 1.7m, a = 0.5m, frequency used = 200KHz
(λ = 1500m), if only one loop antenna is 0 (db), then r = 1m, r
= 100m, the ratio of the above magnetic fields is

[Table] As can be easily understood from this table, in the vicinity of a car (for example, r = 1 m), there is almost no difference from the case of only one loop antenna, but in a place far from the car (for example, r = 100 m), a pair of loop antennas is used. The magnetic fields emitted from the loop antennas 5 and 6 cancel each other out and quickly attenuate and become weaker. Therefore, it is possible to eliminate radio wave interference to surrounding communication devices and the like. It should be noted that, in addition to receiving signals from outside the vehicle as in the above embodiments, it is also possible to receive signals emitted from inside the vehicle while the user of the vehicle enters the vehicle and performs operations such as starting the engine. It can be used as a receiving antenna. Next, the configuration of the portable transceiver 20 will be explained. FIG. 4 is a block diagram showing a portable receiver. This portable transceiver 20 uses radio waves as a means of conveying a unique code. In the figure, 21 is a transmission request signal receiver, which is connected to a transmitter 22 and a code generator 23. The generator 23 outputs to the transmitter 22, and
The alarm generator 24 is output to an alarm generator 24, and the alarm generator 24 is connected to a power supply voltage detector 25. When the transmission request signal receiver 21 receives a transmission request signal from the loop antennas 5 and 6 on the vehicle side, the code generator 23 and the transmitter 22 are activated. The code generator 23 generates a unique code for the portable transceiver 20, and the transmitter 22 modulates the unique code and transmits it as a radio wave. At the same time, the code generator 23 sends a signal indicating that the transmission has been performed to the alarm generator 24 in response to the transmission request. When the alarm generator 24 receives this signal, it emits a warning sound based on the signal from the power supply voltage detector 25 that detects the level of the power supply voltage. This device is configured to emit an intermittent beeping sound when the battery is nearing the end of its lifespan, that is, when the power supply voltage drops, and to emit a continuous beeping sound when there is still some life remaining. There is. In this manner, the portable transceiver 20 detects when the code generator is activated in response to a transmission request, and also monitors the power supply voltage to emit a sound when a transmission occurs and to monitor battery life. Since the portable transmitter is configured to emit a different sound when it approaches, it has the advantage that the operation of the portable transmitter can be confirmed and the battery life can be easily determined. In addition, although sound was used as a means of warning the owner of a portable transmitter/receiver, for example, the oscillator itself or a part of it may vibrate, or a current may be passed through an electrode attached to the oscillator so that the owner feels it. In short, it may be constructed using a means that allows the holder to sense the warning while wearing the portable transmitter/receiver. As explained above, the actuator control device according to the present invention includes a pair of loop antennas facing each other, an inverting circuit interposed between one of the loop antennas and the transmitter, and Because the phases of the carrier waves of the respective radiated transmission request signals are made to be opposite to each other, a magnetic field of the same strength as a single loop antenna can be obtained near the loop antenna, and a magnetic field with the same strength as a single loop antenna can be obtained in the vicinity of the loop antenna. The magnetic field is sufficiently weaker than that of an antenna, and therefore only the magnetic field near the loop antenna is strong, which has the advantage of eliminating radio wave interference to other surrounding devices.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a part of a radio key device for unlocking the door of a car, etc., FIG. 2 is an external view of the car showing an embodiment of the actuator control device according to the present invention, and FIG. FIG. 4 is a block diagram showing a portable transceiver used in the same embodiment. 1...Car door, 2,9,10...Doorknob, 3,11,12...Touch switch, 4,
5, 6... Loop antenna, 7, 8... Door glass, 13... Receiver, 14... Transmitter, 15...
Inversion circuit, 16...Code verification circuit, 17...Code storage circuit, 18...Door lock release actuator, 19...Transmission/reception control circuit, 20...
Portable transceiver, 21... Transmission request signal receiver, 22... Transmitter, 23... Code generator,
24... Alarm generator, 25... Power supply voltage detector.

Claims (1)

[Claims] 1. A transmission request signal is transmitted from a transmitter via an antenna, a unique code emitted from an external device is sensed when the signal is received, and this unique code is compared with a predetermined code, and a In an actuator control device for operating an actuator, a pair of the antennas is provided, and an inverting circuit is interposed between one of the antennas and the transmitter, and the carrier wave of the transmission request signal radiated from each of the pair of antennas is An actuator control device characterized in that phases are opposite to each other.