JP2754237B2 - Keyless entry system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a keyless entry system that transmits and receives a signal that matches a preset key code and causes a receiving device to perform a predetermined operation. .

<Conventional technology> Remote control systems that transmit infrared light from a transmitter to control a target device are being widely used in general home video equipment and audio equipment. In order to allow a single remote controller to control a plurality of devices, a so-called learning remote controller has been developed in which a control signal of each device is memorized.

Also, instead of causing the target device to perform various operations as in the remote control system described above, a preset key code is transmitted and received, and the receiving device performs an operation such as unlocking. Such a keyless entry system is also known and has been put to practical use in lock devices for automobiles and building doors.

These systems generally identify a signal based on a combination of the presence or absence of a pulse, and the operating principle is the same.

<Problems to be Solved by the Invention> Since the operation principle is the same, it is easy to make the learning remote controller memorize the signal of the keyless entry system, and the signal can be easily copied. Therefore, if abused, the security of a system such as a lock device is impaired, so that it is necessary to provide a copy protection function.

The present invention has been made in view of such a problem, and has been made to provide a keyless entry system having a signal copy protection function.

<Means for Solving the Problems> In order to achieve the above-described object, according to the present invention, when transmitting a regular signal, the signal cannot be received in a normal transmission / reception state at a lower level than the regular signal, and In the transmission and reception in the proximity state, a dummy signal of a receivable level is output from the transmitter in addition to the normal signal.

<Operation> As described above, in this type of system, a signal is generally identified by a combination of the presence or absence of a pulse, and the magnitude of the signal level hardly matters. On the other hand, when making the learning remote control memorize signals of other remote controllers, the learning remote controller and the remote controller must be several cm to several tens
Normally, a predetermined operation is performed by approaching to the order of cm, and a dummy signal of such a low level that a signal cannot be received in a normal transmission / reception state by being approached in this manner is recorded in the same manner as a normal signal.

Therefore, when this learning remote controller is used as a transmitter of a keyless entry system, a dummy signal is output at the same level as a regular signal and becomes a signal that does not match a preset key code, and a predetermined signal is transmitted to a receiving device. Cannot be performed.

<Example> Next, one example of illustration is described. FIG. 1 is a timing chart, FIG. 2 is a connection diagram of a transmitter, and a receiver is not shown.

2, 1 is an infrared light emitting diode, 2 is a series resistor, 3 is a switch element using a transistor, 4 is a transmission switch, 5 is a microprocessor, 6 is a power supply battery, and as shown in FIG. , The infrared light emitting diode 1 and the series circuit of the series resistor 2, and the microprocessor 5
It is connected to the.

The microprocessor 5 is a control circuit for the infrared light emitting diode 1, and a key code setting section 7 is connected to a plurality of code input terminals 5a. The key code setting section 7 is a small printed circuit board having a large number of cut sections 7a for setting key codes, and a specific key code is set by selectively cutting off the cut section 7a. When the transmission switch 4 is turned on, the microprocessor 5 operates to output a control signal corresponding to the set key code to the output terminal 5b.
And the switch element 3 is turned on and the infrared light emitting diode 1 emits light.

Reference numeral 8 denotes a transistor connected in parallel to the series resistor 2, and its base is connected to the output terminal 5c of the microprocessor 5.
Are turned on when a normal signal is output and turned off when a dummy signal is output by a control signal output from the microprocessor 6.

This embodiment is configured as described above and operates as follows. In FIG. 1, (a) 11 of FIG.
12 shows a dummy signal, and FIG. 12B shows the on / off state of the transistor 8.

First, when the transmission switch 4 is turned on, the microprocessor 5 operates, a pulse-like control signal corresponding to the recognized key code is output from the output terminal 5b, and the infrared light emitting diode 1 emits light. At the same time, a control signal is output from the output terminal 5c and the transistor 8 is turned on. For this reason, the series resistor 2 is short-circuited, and the light emitting output of the infrared light emitting diode 1 increases, and a regular signal corresponding to the set key code is obtained.
11 is output at a high output level.

When the normal signal 11 ends, the control signal from the output terminal 5c is stopped, and the transistor 8 is turned off.
A pulse-like control signal for a dummy signal is output from the output terminal 5b. For this reason, the series resistance 2 is inserted into the infrared light emitting diode 1, the light emission output thereof is not small, and the dummy signal 12 is output at a level lower than the normal signal 11. Here, the magnitude of the series resistor 2 is set to a low level such that the dummy signal 12 cannot be received by the receiver in a normal transmission / reception state, for example, when transmitting from the outside of the car to the receiver in the car. It is selected to be. Therefore, the receiver does not receive the low-level dummy signal 12 but receives only the normal signal 11 and performs a predetermined operation such as unlocking.

On the other hand, when copied by the learning remote controller, the dummy signal is also handled and recorded in the same manner as a normal signal. As a result, a dummy signal 12 'having the same level as the normal signal 11 is output as shown by the broken line in FIG. 1, and the receiver also receives this dummy signal 12' and outputs a signal which does not match the set key code. Is received, and it does not work.

In the above embodiment, the dummy signal is transmitted after the end of the normal signal. However, the dummy signal can be inserted before the normal signal or in the middle of the normal signal.

<Effect of the Invention> As is apparent from the above-described embodiment, in the present invention, a dummy signal which is lower than a normal signal and cannot be received in a normal transmission / reception state is output from a transmitter. However, even if a learning remote controller is brought close to such a transmitter without knowing the signal format and the transmission signal is copied, it is not possible to cause the receiving device to perform an operation such as unlocking with the copied signal.

Therefore, a keyless entry system having a signal copy protection function can be obtained relatively easily, and the safety of the lock device and the like can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a timing chart of an embodiment of the present invention, and FIG. 2 is a connection diagram of a transmitter. 1 ... infrared light emitting diode, 2 ... series resistance, 4 ... transmission switch, 5 ... microprocessor, 7 ... key code setting section, 8 ... transistor, 11 ... regular signal,
12 ... Dummy signal.

Claims (1)

(57) [Claims] 1. A keyless entry system in which a receiving-side device performs a predetermined operation when a signal transmitted from a transmitter matches a preset key code, and transmits a legitimate signal. In such a case, a dummy signal of a level lower than the normal signal cannot be received in a normal transmission / reception state, and a receivable level in transmission / reception in a proximity state is output from the transmitter in addition to the normal signal. Keyless entry system characterized by doing.