JPS60158734A - Portable device of radio transmitter - Google Patents

Abstract

PURPOSE:To simplify the constitution of a portable device of a radio transmitter by receiving the information transmitted from the switch side by means of an induction electric field to process the information by a microcomputer and producing a signal which modulates the signal transmitted to the switch side from a clock of the computer. CONSTITUTION:The transmission request signal sent from a controller at the car body side is converted into an electric signal by a loop antenna 3 of a portable device and then fetched to a microcomputer 26 via a transmission request receiving circuit 7. The computer 26 uses a miniature crystal oscillator 27 for wristwatch as a clock oscillator. An output port P21 delivers a clock signal, and a frequency multiplying circuit consists of a PLL oscillation circuit 31 and a frequency dividing circuit 32. Then a specific code signal is supplied to a modulation input terminal IN of the circuit 31. The carrier modulated by the specific code signal is supplied to the antenna 3 via an output circuit 4 and transmitted to a controller at the car body side via an induction magnetic field. Thus it is possible to simplify the constitution of the portable device and secures the optimum transmission of signals with a controller at the switch side.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention provides a method for connecting a mobile device such as a transmitter/receiver on the side of an opening/closing body (for example, a vehicle) that opens and closes the door of a car or house (hereinafter referred to as 11111 body). The present invention relates to a wireless transmission device that transmits signals using an induced electromagnetic field as a medium, and particularly relates to a circuit configuration of a portable device thereof.

(Background of the Invention) As an example of a vehicle wireless transmission device using an induced electromagnetic field as a medium, the present applicant previously proposed Japanese Patent Application No. 57-132118 (
There is a ``radio key system'' proposed in 2007 (unpublished).

This radio key system is applied to the door of a vehicle as an opening/closing device, and the door can be unlocked or locked only when a person in possession of a transmitter/receiver, such as the driver, operates a switch installed on the door. The configuration is such that

FIG. 1 is a block diagram showing a schematic configuration of the radio key system (hereinafter referred to as a vehicle locking control device). In the figure, a transmitter/receiver 1 is housed in a card-type case. The card-type receiver 1, which is a portable device, is carried by the driver in place of the mechanical key of the vehicle.

On the other hand, a control device 2 is mounted on the vehicle side, a loop antenna 10 is provided on the door mirror, and a switch 12 is provided near the door handle of the driver's seat door.

The card type transceiver 1 is always powered on and is in a state where it can receive a transmission request signal transmitted from the control device 2 on the vehicle body side. When the driver carrying this card type transceiver 1 manually operates the switch 12 to unlock the door, the transmission request signal generating circuit 11 in the control device 2 shown in FIG. 1 is activated. , the loop antenna 10 transmits the request signal for a certain period of time.
Send from.

The transmission request signal transmitted from the loop antenna 1 is received by the loop antenna 3 of the card type transceiver 1 by electromagnetic induction.

Then, on the card type transceiver 1 side, the transmission request signal detection circuit 7 detects that the transmission request signal is transmitted from the control device @2 on the vehicle 18 side, and activates the code signal generation circuit 8.

When the code signal generation circuit 8 is activated, it outputs a code signal unique to the vehicle 18 (a different code is set for each vehicle and outputs I#), which has been stored in the code storage circuit 9 in advance.

Then, in 6 seconds, the modulation circuit 5 modulates the carrier signal supplied from the carrier oscillation circuit 6 with the code signal, and transmits it through the output circuit 4 and the loop antenna 3.

Then, on the vehicle side, the unique code signal transmitted from the card type transceiver 1 is received by the loop antenna 10, and the received unique code signal is sent to the code matching circuit 14 via the receiving/demodulating circuit 13. Supplied.

The code matching circuit 14 determines whether or not the vehicle-specific code signal registered in advance in the code storage circuit 15 matches the received code signal, and determines whether both code signals match. The actuator drive circuit 16 is driven only in this case.

Then, when the actuator drive circuit 16 is driven,
The actuator 17, which unlocks and locks the door locks, is driven and the doors are unlocked.

In this way, the door lock is unlocked and locked only when the code signal on the card type transceiver 1 side and the code signal registered in the control circuit 2 on the vehicle side match. Even if someone who does not have the transceiver 1 tries to unlock the door, the door will not be unlocked.

Further, even if a person carrying a card type transceiver 1 with a different code signal attempts to unlock the door, the door lock will not be unlocked in the same way.

As a result, the card-type transceiver 1 has the same security performance as a conventional mechanical key.

In addition, since the card-type transceiver 1 can be used while stored in a pocket or bag, it eliminates the need to take out the key every time the key is unlocked or locked, which is required with conventional mechanical keys. Become.

The actuator 17 is configured to reverse the door lock state each time it is driven, and if the door lock is locked before driving, it will unlock the door, and if it is unlocked before driving, it will unlock the door. Perform the locking operation.

By the way, as a result of intensive research in the development of this opening/closing body locking control device, the present applicant has found that 400-5 is the transmitting carrier for transmitting the unique code signal from the transceiver 1 side.
Blue indicates that the optimum frequency is around 00KHz.

As a carrier for transmitting a unique code signal, it is possible to reliably transmit and receive signals to and from the vehicle only within the range where the user actually attempts to open the door, that is, within a radius of about one inch around the door. When the door is outside, it is required to have a characteristic that makes it impossible to transmit or receive data at all, in the sense that it prevents anyone other than the user from unlocking the door.

Furthermore, in order to avoid adverse effects on other wireless devices, etc., it is necessary to have an electric field 1 strength characteristic that rapidly attenuates with distance. Figure 2 shows a 10A square loop antenna with a side of 10cm.
It is calculated by converting the strength of the magnetic field induced when a current flows through the turn into electric field strength. As is clear from this example, in the case of wireless transmission using the induced 1j electromagnetic field as a medium, the lower the fatigue number, the greater the attenuation over distance, which is a desirable characteristic for this vehicle locking control device. I understand.

Furthermore, considering that 530'K)-12 or higher is the frequency band of general AM broadcasting, it is suitable that the transmission carrier frequency of the unique code signal is 530KH2 or lower.

On the other hand, Figure 3 (Source: Electronic Communication Handbook, published by Ohmsha, edited by the Institute of Electronics and Communication Engineers), March 30, 1970, 1st edition, No. 1
As is clear from Figure 5 on the left on page 1543, the spatial noise component increases as the frequency decreases, which is disadvantageous to the transmission and reception of weak radio waves as in the present invention, and when the carrier wave frequency is extremely low, the spatial noise component increases. Another problem arises in that modulation and demodulation using codes become difficult.

Taking all of the above into consideration, it was concluded that the optimal transmission carrier frequency for the unique code is around 400 to 500 K'HZ.

The unique code signal transmitted in this way is received by the vehicle body control device 2.
The demodulation circuit 13 needs to be set to have as narrow a band as possible. This is because when trying to receive in a wide band, unnecessary noise components increase, and if the unique code signal is weak, it becomes impossible to receive and demodulate it.

On the other hand, in order to receive in a narrow band, the frequency of the transmitting carrier emitted from the card side is required to be extremely stable, so the characteristic element that determines the carrier frequency in the oscillation modulation circuit is crystal oscillation. A child is needed.

However, since 400 to 500 KHz crystal resonators are not used in large numbers, there are no small enough ones that can be stored in cards, and manufacturing new small ones would be extremely expensive. , there was a problem in that it led to an increase in the cost of the portable transmitter/receiver 4@ machine.

(Objective of the Invention) The object of the present invention is to enable reliable transmission and reception between a portable device, such as a card-type transmitter/receiver, and a control device on the opening/closing body side in a locking till device for an opening/closing body.
The aim is to reduce the cost of portable devices.

(Structure of the Invention) In order to achieve the above object, the present invention utilizes, for example, the code signal generation circuit 8. Information processing unit consisting of code storage circuit 9, etc.! ! I! The device is characterized in that the carrier of the modulation circuit 5 is formed by multiplying the clock of this microcomputer by one PL circuit.

(Description of Embodiments) FIG. 4 is a diagram showing the electrical configuration of the portable device 1 according to the present invention. In the figure, a transmission request signal transmitted from a vehicle body control unit is converted into an electrical signal by a loop antenna 3 and a tuning capacitor 2o.

The analog switches 21a and 21b are for preventing the transmission request receiving circuit 7 from malfunctioning when outputting the unique code.
are output ports P of the microcomputer 26, 3. P4
When the unique code is output, the analog switch 21a is turned on and the analog switch 21b is turned off.

The transmission Riffist signal converted into an electrical signal is detected by the detection circuit 22 and becomes a low frequency signal (demodulated), and this low frequency signal is amplified by the amplifier circuit 24 using a low power consumption operational amplifier, and then sent to the input port P1. The data is taken into the microcomputer 26 from there.

The Zener diode 23 is used to protect the amplifier circuit 24 from excessive input such as noise, and the negative power supply circuit 25 is used to protect the amplifier circuit 24 from O to 3V pulses output from the output port P2 of the microcomputer 26 for low power consumption operational amplifiers. This is a circuit that creates a negative power supply.

The microcomputer 26 is powered by a button-type lithium battery 2
For example, it is a small and low power consumption CPU that can be driven at
, 768 KHz) is used as the clock oscillator.

When the transmission request signal is received with an intensity above a certain value, the output of the amplifier circuit 24 exceeds the input threshold level of the microcomputer 26, and the transmission request signal is detected.

When the microcomputer 26 detects the transmission request signal, it reads the unique code from the unique code storage section 9 through the ports P6 to P20, and outputs this as serial data to the outside from the boat P6. Further, the analog switches 21a and 21b transmit the control signal to P3. Output from P4,
Preventing malfunction of the receiving circuit.

Output port P21 outputs an O-check signal.

In this example, the resonance frequency of the crystal oscillator 27 is 32°768
It is set equal to KH2.

The PLL oscillation circuit 31 and the frequency division circuit 32 constitute a frequency multiplication circuit, and a unique code signal is input to the modulation input terminal IN of the PLL oscillation circuit 31.

The PLL oscillation circuit 31 has an input a to the phase detection section.

Once the frequencies of b match, a steady state, ie, a locked state is reached. If the frequency division ratio of the frequency divider circuit 32 is 14, the output C of vCO at this time is the frequency of the a input, 32.768K.
14 times Hz, or 458.752KHz,
Further, if the frequency division ratio is set to 15, the carrier frequency becomes 491.520 KHz, which makes it possible to obtain the optimum carrier frequency for this transmission.

Next, the carrier modulated with the unique code signal is supplied to the loop antenna 3 via the output circuit 4, and sent to the control device on the vehicle body side using the M conductive electromagnetic field as a medium.

Since the subsequent operation on the vehicle body side has already been explained, it will be omitted here.

In the above embodiment, only the unique code signal generation process was performed in the microcomputer 26, but more advanced functions such as performing various complicated data processing in response to the transmission request signal and sending the processing results back to the vehicle body are also possible. Information processing may be performed, and the present invention can also be applied to systems in which signals transmitted from the vehicle body are coded with consideration for theft prevention and the demodulated code is discriminated by a microcomputer. Of course.

(Effects of the Invention) According to the configuration of this invention, a dedicated crystal oscillator is not required to create a transmission carrier of 400 to 500 KH2, which makes it possible to reduce the cost of the portable device while controlling the portable device and the opening/closing body side. This enables optimal signal transmission between devices.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the electrical configuration of a vehicle lock control device previously proposed (unpublished) by the applicant, and FIG. 2 is a graph showing the calculation results of the magnetic field strength induced by the loop antenna. FIG. 3 is a graph showing the frequency characteristics of general spatial noise, and FIG. 4 is a circuit diagram showing the electrical configuration of the device of the present invention. 1... Portable device 2... Car body side control @ installation 3... Loop antenna 9... Unique code storage section 26... Microcomputer 27... Crystal oscillator 31... PLL Oscillation circuit 32... Frequency divider circuit Patent applicant Nissan Motor Co., Ltd. Figure 2 0 25 50 75 +00 +25
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Claims (1)

[Claims] (1) A loop coil that receives information transmitted from the opening/closing body side using an induced electromagnetic field; demodulation means that demodulates received information from a received signal of the loop coil; and a demodulation means that responds to the demodulated information. information processing means for performing predetermined processing; modulation means for modulating the information processing result with a carrier of a predetermined frequency; and 1! for the modulated output. A loop coil that sends out to the opening/closing body side using a conductive electromagnetic field, and a six-pin arrangement; the information processing means is constituted by a microcomputer, and the carrier of the modulation means multiplies the clock of the microcomputer by a PLL circuit. A portable wireless transmission device characterized by: