JPH0283699A - Burglar preventing device - Google Patents

Abstract

PURPOSE:To surely operate an alarm when a body passes a normal section by switching a transmission band area switching means from a spot operation to a sweep operation by detecting the body by a sensor which detects the approaching of the body to the normal section, and detecting the fact at no alarm from a tag device is detected by an alarm detecting means. CONSTITUTION:When a person approaches the normal section A, a relay contact 19 is turned on by detecting an infrared ray by an infrared ray detecting part 22, and a wave B of frequency fo is emitted from an antenna device 6. When the tag device whose reception characteristic is deviated is used a control means 29 switches a switch 16 to a control voltage generation circuit 17 side when the fact that (no specific wave exists) is judged by the alarm detecting means 27 after the wave B of frequency fo is transmitted. Therefore, the operation of the wave B is switched from the spot operation of frequency fo until then to the sweep operation sweeping with the frequency fOH higher than fo from a lower limit frequency fOL, and the alarm is operated when the frequency of the wave B coincides with the reception characteristic R1 or R2. In such a way, it is possible to surely generate the alarm even when deviation is generated in the reception characteristic of the tag device.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to an anti-theft bag that detects when an item on display that is subject to CA protection has been illegally taken out of a controlled area.

Prior Art FIG. 5 shows the external appearance of a tag device 2 attached to each cA protected target crystal 1. The tag device 2 has a built-in alarm 1hi3, a battery 4, etc. as shown in FIG.
3 is turned off by the switch section 5. Near the entrance of the store where protected item 1 is displayed, there is a
As shown in the figure and FIG. 8, an antenna device 6 is installed that emits radio waves B to a specified area. Reference numeral 7 indicates a checkout table where customers and shopkeepers receive money and hand over protected items 1, and 8 is an entrance/exit.

In a normal sales format, the store 1j uses a special procedure to remove the tag device 2 from the protected product 1 at the checkout table 7, and only the product is handed over to the customer, who then attaches the tag device 2. The customer goes from the checkout table 7 through the designated area A and exits the store from the entrance 8 with the unfilled items.

In a shoplifting situation, when the protected item 1 with the tag device 2 passes through the specified area A, the receiving section 9 of the tag device 2 detects the radio wave B emitted from the antenna device 6 and activates the switch section 5. When activated, the alarm 3 is turned on and an alarm sound and specific radio waves are emitted in the vicinity, promptly notifying the store staff that shoplifting has occurred.

As shown in FIG. 6, the transmitter 1110 that provides a signal to the antenna device 6 is composed of a power amplification section 11 and an oscillation circuit 12, and the frequency control terminal 13 of the oscillation circuit 12 has a
Conventionally, a constant voltage circuit 14 is connected.

15 is a variable capacitance diode.

Problems to be Solved by the Invention In such a conventional configuration, the constant voltage circuit 14 is operated so that the frequency of the radio wave B emitted from the antenna device 6 becomes fO.
The output voltage of the oscillation circuit 12 is changed by varying the capacitance of the variable capacitance diode 15, and the receiving frequency of the receiving section 9 of the tag device 2 attached to each protected item 1 is set to the frequency fo. The pitch of the antenna coil of the receiving section 9 is adjusted so that.

However, the reception frequency of the tag device 2 shifts during use, and as shown in FIG. 9, the reception characteristics of R1 or R2 change.
If the frequency fQ of the radio wave B of the transmission @io deviates significantly, there is a serious problem that the alarm 3 will not operate even if the target crystal 1 with the tag device passes through the specified area A.

An object of the present invention is to provide an anti-theft device in which the alarm 3 of a tag device is reliably activated when the tag device passes through a specified area A even if the tag device has reception characteristics that are deviated from the frequency fo.

Means for Solving the Problems The anti-theft device of the present invention includes an antenna device that is connected to the output of a transmitter and emits radio waves in a specified area, and an antenna device that is attached to an item to be protected and that detects the radio waves from the antenna device and generates an alarm. and a transmitting IFbl that switches the operating state of the oscillation circuit of the transmitter between a spot operation that oscillates a specific frequency and a sweep operation that sweeps from a lower limit frequency including the specific frequency to an upper limit frequency.
I switching means is provided, sensor means is provided for detecting that an object approaches the specified area, and alarm detection means is provided for detecting generation of an alarm from the tag device, and the sensor means detects the object and the alarm is detected. The present invention is characterized in that a control means is provided for detecting a state in which the means is not detecting an alarm from the tag device and switching the transmission band switching means from a spot operation to a sweep operation.

Effect: According to this configuration, if the reception characteristics of the tag device do not deviate, the radio wave of the frequency fQ of the transmitter is detected and the alarm of the tag device is activated. If the reception characteristics of the tag device are out of alignment, the alarm detection means will not detect an alarm from the tag device even if the sensor means detects the approach of an object to the specified area, so the control means will change the transmission band switching means. The switch is switched and the radio wave B is emitted from the transmitter by sweeping from the lower limit frequency f1 through fQ to the upper limit frequency f2, and the tag is attached! When the frequency of radio wave B matches the shifted reception characteristics, the tag device generates an alarm.

Embodiments Hereinafter, embodiments of the present invention will be explained based on FIGS. 1 to 4. Components having the same functions as those shown in FIGS. 5 to 8 showing the conventional example will be described with the same reference numerals.

FIG. 1 shows the configuration of a transmitter 10 in a theft alarm device of the present invention.A frequency control terminal 13 of an oscillation circuit 12 is connected to a constant voltage circuit 14 and a control m+ voltage generation circuit via a switch 16 as a transmission band switching means. 17 are connected. The constant voltage circuit 14 receives a signal S1 of a preset constant voltage VO.
is applied to the variable capacitance diode 15, and the control voltage generation circuit 17 generates a predetermined repetition period [for example, 3H] over time.
z] is generated. When the switch 16 is connected to the constant voltage circuit 14 side, the oscillation frequency of the oscillation circuit 12 becomes constant continuously, and the frequency f is output from the power amplification section 11 via the antenna device i6.
cl radio wave B is emitted. Signal S of control voltage circuit 17
2 is level ■1 lower than level ■0 to level ■1
When the switch 16 is connected to the control voltage circuit 17 side, the frequency of the radio wave B generated from the power amplifying section 11 is f. L””
2. FIG. 2 shows the frequency relationship between the signal S2 and the radio wave B.

A power supply voltage is constantly applied to the oscillation circuit 12 from a power supply 18, and an @a voltage is applied to the power amplification section 11 from the power supply 18 via a relay contact 19.

The coil 20 activating the relay contact 19 is energized by sensor means 21 which detects the proximity of an object to the defined area A. The sensor means 21 has a detection window in a specified area A.
and a one-shot multivibrator-type timer 23 that is triggered when the infrared detector 22 detects infrared rays of a specified level or higher, and the output of the timer 23. It is composed of a transistor 24. The specific mounting position of the infrared detection unit 22 is as shown in FIG.
an exterior case 26 of the antenna device 6 attached to the antenna device 5;
Alternatively, as shown in FIG. 4, an example can be given in which they are arranged from four directions toward the prescribed area A. therefore,
Until a person enters the detection area of the infrared detection unit 22, the transistor 24 is off, the relay contact 19 is open, and the power amplification unit 11 is not energized. When an intrusion occurs, it detects infrared rays that are naturally radiated from the human body and activates the timer 23.
The coil 20 is excited for a predetermined period of time, the relay contact 19 becomes a make state, the power amplifying section 11 is energized, and the radio wave B is emitted from the antenna device 6 for a predetermined time of the timer 23.

A switch 16 is connected to the constant voltage circuit 14 at the beginning of the limb, and when a person approaches the specified area A, the infrared detection unit 22
detects infrared rays, relay contact 19 is turned on, and radio wave B of frequency fo is emitted from antenna device 6. If you have a protected item 1 with a tag device with normal reception characteristics, the receiver 9 of the tag device 2 detects the radio wave B and the alarm 3 operates, emitting an alarm sound and a specific signal. A radio wave Bffi is emitted to notify the store manager that a shoplifting incident has occurred.

In the case of the tag device 2 whose reception characteristics are off, the receiver 9 does not operate even with the radio wave B of frequency fO, so the alarm 3
No alarm sounds or specific radio waves are generated. Here, the alarm detection means 27 detects whether the specific radio wave is included in the signal received by the receiving antenna 28, and the control device P112
9 is the alarm detection means 27 after transmitting the radio wave B of frequency f(l).
When it is determined that there is no specific radio wave J, the switch 16 is switched to the control voltage generation circuit 17 side.As a result, the radio wave B is not a spot operation with a frequency fQ as before, but a lower limit frequency f lower than f[+ Switches to spot operation that sweeps over f., 4, which is higher than .t, %fo, and when the frequency of radio wave B matches reception characteristic R1 or R2, alarm 3 is activated to detect shoplifting. to be notified.

Note that when the alarm detection means 27 detects that "specific radio waves are present", the control means 29 does not switch the switch 16.

In the embodiment described in F, the sensor means 21 has been described as one that detects infrared rays, but it is also possible to use a Doppler type proximity sensor using radio waves in the uFtF band or ultrasonic waves.

Effects of the Invention As described above, according to the present invention, the operating state of the oscillation circuit of the transmitter that emits radio waves to the tag device is swept from a spot operation that oscillates a specific frequency and a lower limit frequency that includes the specific frequency to an upper limit frequency. a transmission band switching means for switching to a sweep operation; a sensor means for detecting that an object approaches a specified area; an alarm detection means for detecting the occurrence of an alarm from the tag device; Since a control means is provided for detecting a state in which the alarm detecting means is not detecting an alarm from the tag device and switching the transmission band switching means from spot operation to sweep operation, the tag device does not send back an alarm. By performing a sweep operation on the transmitter when the signal is not received, an alarm can be reliably generated even if a deviation in reception characteristics of the tag device occurs.

In addition, since the transmitter performs sweep operation only when no alarm is returned from the tag device, it is possible to avoid a situation where a wide frequency band is always monopolized, and from the standpoint of effective use of the frequency band. This is preferable.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a transmitter in the anti-theft device of the present invention, FIG. 2 is an explanatory diagram of spot operation and sweep operation, and FIG.
4 and 4 are a schematic vertical cross-sectional view and a plan view showing the mounting position of the sensor means, FIG. 5 is an exploded perspective view showing the attached state of the tag device, FIG. 6 is a configuration diagram of a conventional anti-theft device, and FIG. 7 and 8 are a schematic longitudinal cross-sectional view and a plan view showing the mounting position of the antenna device, and FIG. 9 is an explanatory diagram of the deviation in reception characteristics of the tag device. DESCRIPTION OF SYMBOLS 1... Product to be protected, 2... Tag device, 6... Antenna device, 10... Transmitter, 12... Oscillation circuit, 1
3... Frequency control terminal, 14... Constant voltage circuit, 16
... switch [transmission band switching means], 17 ... control voltage generation circuit, 21 ... sensor means, 27 ... alarm detection means, 29 ... control means, A ... specified area. Agent Yoshihiro Morimoto 2-' Figure 3 Figure 4 Figure 4 Figure 4

Claims (1)

[Claims] 1. An antenna device that is connected to the output of the transmitter and emits radio waves to a specified area, and a tag device that is attached to the item to be protected and that detects the radio waves from the antenna device and generates an alarm, and the transmitter transmission band switching means for switching the operating state of the oscillation circuit between a spot operation in which a specific frequency is oscillated and a sweep operation in which the operation is swept from a lower limit frequency including the specific frequency to an upper limit frequency; and an alarm detection means for detecting occurrence of an alarm from the tag device, and detects a state in which the sensor means detects an object and the alarm detection means does not detect an alarm from the tag device. An anti-theft device comprising control means for switching a transmission band switching means from spot operation to sweep operation.