JPH04153481A - Keyless entry device - Google Patents

Abstract

PURPOSE:To keep maximum receiving distance constant by a method in which the voltage sensor of transmitter, the comparator of voltage difference, and a threshold value setter to set up voltage by comparison of the reference voltage of the transmitter are connected with circuits in order. CONSTITUTION:In a keyless entry device, a voltage sensor circuit 7, a comparator circuit 8 to detect voltage difference between the voltage of the circuit 7 and the set reference voltage, and a threshold value setting circuit 9 are connected and they are connected to a signal detection circuit 10. The circuit 7 is connected to an arithmetic circuit in such a way as to permit connection only when voltage detected is less than a preset reference voltage, and a signal intensity calculated in the circuit 8 is input. In the circuit 9, a threshold value is set up so that signal of less than a given intensity is made impossible to detect and the circuit 9 is connected to the circuit 10. The signal-receiving distance can thus be kept constant regardless of voltage.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a locking/unlocking device that wirelessly locks and unlocks a door as an alternative to a mechanical key.

(Prior Art) A general keyless entry device is composed of a transmitter and a receiver, and the receiver locks and unlocks the lock by receiving a signal transmitted from the transmitter.

For example, a keyless entry device as shown in FIGS. 5 and 6 is disclosed in Japanese Utility Model Application No. 60-159266. The conventional technology will be explained below based on FIGS. 5 and 6.

The transmitter 23 is composed of a power source 24, a transmitting circuit 25, and a transmitting antenna 26.
5 is activated to generate a signal, and this signal is transmitted from the transmitting antenna 26.

The receiver 33 includes a receiving antenna 34 and a receiving circuit 35. A signal received by the receiving antenna 34 of the receiver 33 is inputted to the signal detector 44 and threshold setter 66 via the receiving circuit 35.

In the threshold setter 66, a threshold is set to a predetermined level (for example, 1/2 of the input signal strength) according to the strength of the input signal, and this threshold is set to a predetermined level (for example, 1/2 of the input signal strength).
Output to 4.

In the signal detector 44, the threshold value outputted from the threshold value setting device 66 is compared with the strength of the received signal, and when the strength of the signal exceeds the threshold value, that signal is detected and the signal is It is input to the collation device 55.

The signal-υ verifier 55 is composed of a signal verification circuit 56, an output circuit 57, and a signal storage circuit 58, and the signal manually input to the signal verification circuit 56 is a unique signal stored in advance in the signal storage circuit 58. The lock/unlock signal is outputted via the output circuit 57 only when the characteristics of both signals, such as signal period and signal waveform, are the same.
is input to.

Here, various noises are mixed into the received signal depending on the external environment of the receiver 33. This received signal is input to the signal detector 44 via the receiving circuit 35. When the noise level of the signal input to the signal detector 44 exceeds the threshold, the signal mixed with this noise is input to the signal checker 55, but this signal is not a pre-stored signal. Since the characteristics are not the same, the lock/unlock signal is not output. Therefore, in order to lock and unlock the door, it is necessary to reset the threshold value to a value higher than the noise level. Therefore, when the transmitter 23 is moved closer to the receiver 33 and transmission is performed, the strength of the received signal becomes stronger, and the strength of the input signal to the threshold setting device 66 becomes stronger. By setting the threshold to a high value depending on the strength of this input signal, the threshold is set to a value higher than the noise level, and the noise is removed from the output of the signal detector 44.

The lock/unlock device 77 is composed of an actuator drive circuit 78, an actuator 79, and a lock 80.
When a signal is input from the i verifier 55, the actuator drive circuit 78 is activated, the actuator 79 is driven, and the lock 80 is locked and unlocked.

The conventional technology has been described above. In the conventional technology described above, as the distance from the transmitter 23 to the receiver 33 (hereinafter referred to as reception distance) increases, the strength of the received signal weakens, and the threshold value increases. approaching noise level. As a result, the signal from the transmitter 23 may be able to be received at such a distance that the owner of the transmitter 23 cannot see the door locked by the lock 80. In such a case, it is not preferable that the transmitter 23 is operated unconsciously and locked/unlocked against the intention of the owner of the transmitter 23. Therefore, it is necessary to set the maximum reception distance so that locking/unlocking is not performed from a position further away than a certain distance.

Here, when attempting to set the maximum reception distance in the above-mentioned conventional technology, a method can be considered in which a lower limit of a threshold value is set to determine a lower limit of detectable signal strength, and the maximum reception distance is set.

(Problems to be Solved by the Invention) However, in the case of a transmitter operated by a built-in power supply, the strength of the transmitted signal fluctuates due to fluctuations in the power supply voltage. Therefore, even if the lower limit of the threshold is set, the maximum reception distance is not kept constant, and when the power supply voltage becomes higher than the reference voltage, the maximum reception distance becomes longer, and the transmitter owner closes the door. It is undesirable for locking and unlocking to be carried out in conditions that cannot be confirmed. Furthermore, if the power supply voltage becomes lower than the reference voltage, the maximum reception distance will be shortened, and the transmitter will not be received unless it is brought closer to the receiver than usual, resulting in poor usability.

An object of the present invention is to maintain a constant maximum reception distance by changing a threshold value in accordance with changes in transmitter power supply voltage.

(Means for Solving the Problems) A keyless entry device according to the present invention includes a transmitter that transmits a signal using a built-in power supply, a receiver that receives the signal transmitted from the transmitter, and a signal that is received by the receiver. a signal detecting means for comparing the signal strength of the detected signal with a predetermined threshold value and detecting a signal strength exceeding the threshold; and a signal detecting means for detecting a signal strength exceeding the threshold; a signal matching means for comparing the signal received by the locking signal with a locked signal stored in advance and outputting a locking/unlocking signal only when the characteristics of both signals are the same; and a locking/unlocking signal output from the signal matching means. A keyless entry device comprising: a locking/unlocking device that locks and unlocks a door in response to a lock signal; and a voltage detecting means for detecting a power supply voltage of the transmitter; comparing the voltage detected by the voltage detecting means with a predetermined reference voltage. a comparison means for detecting a voltage difference between the reference voltage and the reference voltage; and according to the voltage difference detected by the comparison means, if the voltage is lower than the reference voltage, the threshold value is set lower; The present invention is characterized by comprising: threshold setting means for setting a higher threshold when the voltage is higher than the reference voltage.

(Function) In the present invention, when the transmitter power supply voltage detected by the voltage detection means is lower than a predetermined reference voltage, the threshold value is set low, and when it is high, the threshold value is set high. Since the threshold value is set in this way, the preset maximum reception distance is kept constant regardless of changes in the transmitter power supply voltage.

With the threshold set in this way, if a signal is transmitted from a distance greater than the preset maximum receiving distance, this signal is received by the receiver and compared with the threshold; Since the strength does not exceed the threshold, it is invalidated and no lock/unlock signal is output.

Moreover, it goes without saying that this threshold value is set to a value higher than the noise level.

(Example) Next, an example of the present invention will be described based on FIGS. 1, 2, 3, and 4.

The key cylinder entry device in this embodiment is a keyless entry device used in automobiles.

In this embodiment, a transmitter 1 (3Jt) is installed in the Igni.

On the other hand, a terminal 6 is provided on the key cylinder 101 on the automobile side, corresponding to the terminal 5 on the transmitter 1 side, and this terminal 6 is connected to the voltage detection circuit 7.

Here, the ignition key 10 is attached to the key cylinder 101.
When the terminal 0 is inserted, the terminals 5 and 6 are connected, and the voltage of the transmitter 1'a2 is detected by the voltage detection circuit 7.

The voltage detection circuit 7 is connected to a warning device 16, and the detected voltage is compared with a preset lower limit value, and when it falls below the lower limit value, the warning device 16 is activated to notify that the battery is exhausted. Further, the voltage detection circuit 7 is connected to the arithmetic circuit 8, and when the voltage detected by the voltage detection circuit 7 is equal to or higher than a preset lower limit value, the voltage is manually inputted to the arithmetic circuit 8. This arithmetic circuit 8 compares the input voltage with a predetermined reference voltage, and depending on the voltage difference, determines a preset maximum receiving distance based on the power supply voltage-transmission signal strength characteristic as shown in FIG. The signal strength at is calculated.

The arithmetic circuit 8 is connected to a threshold setting circuit 9, and the signal strength calculated by the arithmetic circuit 8 is input to the threshold setting circuit 9. In the threshold setting circuit 9, a threshold is set so that a signal weaker than this signal strength cannot be detected. Further, this threshold setting circuit 9 is connected to a signal detection circuit 10, and the set threshold value is inputted to the signal detection circuit 10.

The power source 2 of the transmitter 1 operates the transmitting circuit 3 to transmit a signal from the transmitting antenna 4, and this signal is received by the receiving antenna 12 of the receiver 11. This receiving antenna 12 is connected to a receiving circuit 13, and this receiving circuit 13 is connected to a signal detecting circuit 10 and a signal matching circuit 17.

The received signal passes through the receiving circuit 13 to the signal detecting circuit 1.
0 and is input to the signal matching circuit 17.

The intensity of the signal input to the signal detection circuit 10 is compared with a threshold value, and only the signal intensity exceeding the threshold value is detected and output to the output circuit 18.

On the other hand, the signal matching circuit 17 stores in advance unique signals that differ for each receiver, and the signal output from the receiving circuit 13 and input to the signal matching circuit I7 is compared with the unique signal, and only when they are the same, the signal is compared with the unique signal. It is output to the output circuit 18. This output circuit 18 includes the signal detection circuit 10 and the signal matching circuit 17.
A lock/unlock signal is output to the lock/unlock device 19 only when outputs from both sides are received.

■ The lock/unlock device 19 is composed of an actuator drive circuit 2o, an actuator 21, and a lock 22. The output from the output circuit 18 operates the actuator drive circuit 20 to drive the actuator 21, and the lock 22 is activated.
lock or unlock.

Next, the effects of this embodiment will be explained.

When the voltage of the power supply 2 of the transmission a1 is lower than a predetermined reference voltage, the threshold value is set low, and when it is higher, the threshold value is set high. Therefore, the preset maximum receiving distance is kept constant regardless of changes in the voltage of the power source 2.

Further, the ignition key 100 is connected to the key cylinder 101.
Since the voltage of the power source 2 of the transmission ml built into the ignition key 100 is detected when the ignition key 100 is inserted into the ignition key 100, there is no need to perform any special operation when detecting the voltage.

Furthermore, if the detected voltage is lower than a preset lower limit value, a warning that the battery is running out is issued, so it is possible to accurately know when it is time to replace the battery.

(Effect of the invention) Since the maximum receiving distance is kept constant regardless of changes in the transmitter power supply voltage, locking and unlocking from an undesirable long distance is reliably prevented, and the receiving distance is also reduced due to a decrease in the transmitter power supply voltage. is not shortened, and usability is improved.

[Brief explanation of the drawing]

FIGS. 1, 2, 3, and 4 are diagrams of embodiments of the present invention. FIG. 1 is a block diagram showing the connections between each component, and FIG. 2 is a block diagram showing the control method. FIG. 3 is a graph showing the relationship between the transmitter power supply voltage and the transmitter power supply voltage, and FIG. 4 is a graph showing the relationship between the transmitter power supply voltage and the number of times the transmitter is used. 5 and 6 are drawings of the prior art, with FIG. 5 showing a block diagram showing connections between each component, and FIG. 6 showing a flowchart showing a control method. ■ 00. Transmitter ■ Terminal (key side) Terminal (cylinder side) Voltage detection circuit Arithmetic circuit Threshold setting circuit Signal detection circuit Receiver warning device Signal verification circuit Locking/unlocking device

Claims (1)

[Claims] A transmitter that transmits a signal using a built-in power supply, a receiver that receives the signal transmitted from the transmitter, and a signal strength of the signal received by the receiver and a predetermined threshold. a signal detection means for detecting a signal strength exceeding the threshold value by comparing the signal strength with the signal strength that exceeds the threshold; and a signal detection means for detecting a signal strength exceeding the threshold value; signal matching means that outputs a locking/unlocking signal only when the characteristics of both signals are the same, and a locking/unlocking means that locks/unlocks the door in response to the locking/unlocking signal output from the signal matching means. A keyless entry device comprising: a voltage detection means for detecting a power supply voltage of the transmitter; and a voltage detection means for comparing the voltage detected by the voltage detection means with a predetermined reference voltage to determine a voltage difference between the voltage and the reference voltage. a comparison means to detect, and a voltage difference detected by the comparison means to set the threshold low if the voltage is lower than the reference voltage, and to set the threshold low if the voltage is higher than the reference voltage; A keyless entry device comprising: threshold setting means for setting a high value;