JPH07210770A - Alarm sound generation device - Google Patents

Abstract

PURPOSE:To provide the alarm sound generation device which operates on receiving an alarm sound operation signal and an alarm sound stop signal by one resonance circuit. CONSTITUTION:This device is provided with the resonance circuit 1 which receives the alarm sound operation signal and alarm sound stop signal, a signal discrimination circuit which counts the alarm sound operation signal by a counter 9, a monostable multivibrator 10, a monostable multivibrator 11, and a NAND circuit 12 and also counts the alarm sound stop signal by a low-pass filter 13, a counter 14, a monostable multivibrator 15, a monostable multivibrator 16, and a NAND circuit 17, and a driver circuit 18 which drives a buzzer 8 with the signal from the signal discrimination circuit to generate or stop an alarm sound.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a warning sound generating device in which a tag or the like used for shoplifting / theft prevention or the like issues an alarm or the like by itself.

[0002]

2. Description of the Related Art Conventionally, as this type of warning sound generator,
For example, a gate (antenna) using an electromagnetic induction coupling method
There is a device that detects the electromagnetic wave and emits a warning sound.

Such a warning sound generating device is placed on the sales floor by being attached to a sleeve of clothes, which is a product, through a wire, a pin, an adhesive tape or the like. And if you take out the product without buying it, this warning sound generator will pass through the gate installed near the checkout place while attached to the product, and the warning sound generator will emit electromagnetic waves of a specific frequency from the gate. Detects and emits a warning sound. Further, if the user tries to take out the product by forcibly removing the warning sound generation device from the product, the warning sound generation device detects that the wire or the like has come off, and also generates the warning sound.

On the other hand, in the case of normal shopping, the customer places the product to which the warning sound generating device is attached at the cash register, and the accountant removes the detection function of the warning sound generating device and then removes it. Therefore, the warning sound does not sound. This cancellation method is a mechanical method that prevents the warning sound generator from generating a warning sound by using a special jig, or a warning sound stop signal with a frequency different from the warning sound operation signal. There is a method using radio waves to prevent the generator from generating a warning sound.

Next, FIG. 5 shows an example of conventional warning sound cancellation by radio waves. In the figure, the driver circuit 7
Sounds the buzzer 8 when the terminal connected to the lock hold circuit 6 falls to the ground, and conversely the terminal supplies the internal power supply voltage V
It is set to stop the buzzer 8 when lifted to cc. The resonance circuit 1 including the capacitor C1 and the inductor L1 is tuned to the warning sound activation signal frequency f1,
The resonance circuit 2 including the capacitor C2 and the inductor L1 is tuned to the warning sound stop signal frequency f2.

[0006] When a customer passes through a gate installed near a checkout place with the alarm sound generator attached to the product without buying the product, the alarm sound generator outputs the alarm sound activation signal frequency f1 to the resonance circuit 1 The lock hold circuit 6 is closed, the input terminal of the driver circuit 7 is dropped to the ground, and the buzzer 8 sounds.

When the warning sound generator receives the warning sound stop signal frequency f2 at the resonance circuit 2, its peak value is A
It is converted into a DC voltage by the C / DC converter 3. When this voltage becomes higher than the reference voltage Vref, the output of the comparator 4 is inverted and the switch 5 is closed to drop it to the ground, so that the lock hold circuit 6 is opened and the driver circuit 7 is opened.
The input terminal of is raised to the internal power supply voltage Vcc and the buzzer 8 is stopped.

Further, since the lock hold circuit 6 is closed by removing the wires, pins, adhesive tape, etc. (not shown) of the warning sound generating device, the buzzer 8 sounds when the customer removes the warning sound generating device from the product. . Then, if a warning sound stop signal transmitter (not shown) of frequency f2 is installed at the checkout place, the switch 5 will be grounded while the accountant removes the warning sound theft prevention device wire from the product, As a result, the lock hold circuit 6 is forcibly opened, and there is no inconvenience that the buzzer 8 sounds.

On the other hand, in order to cancel the mechanical warning sound, for example, there is a method of inserting a rod-shaped jig from the outside of the warning sound anti-theft device housing and mechanically closing the switch 5 to ground it.

[0010]

The above-described cancellation of the warning sound by radio waves has an advantage over the mechanical warning sound in that the accounting work can be performed smoothly without the need for a special accountant to use a special jig. is there. However, the frequency selection characteristics of the resonant circuit that receives signals with two different frequencies are not very good, and even if the frequency difference is set high, harmonic components due to distortion of low-frequency signals and other electronic devices Erroneous radiation and electrostatic noise are likely to cause malfunctions. Further, since a high-sensitivity resonator needs to use an expensive ferromagnetic material such as permalloy for the inductor, there is a problem that cost increase cannot be avoided.

[0011]

In order to solve the above problems, the present invention receives a first radio wave signal to generate an alarm sound and receives a second radio wave signal to stop the alarm sound. In the warning sound generating device configured as described above, a single electromagnetic coupling means for receiving the first and second radio wave signals, a signal identifying means for identifying the signal received by the electromagnetic coupling means, and the signal identification It is intended to provide a warning sound generating device provided with a warning sound generating means for generating a warning sound according to the output of the means.

In the present invention, the first radio wave signal is a continuous sine wave warning sound actuation signal having a frequency receivable by the electromagnetic coupling means, and the second radio wave signal is the electromagnetic coupling means. The signal identification means counts the wave number of the warning sound actuation signal and reaches a certain number, and then controls the warning sound generation means to generate a warning sound. In addition to the above, the present invention provides a warning sound generation device for counting the intermittent number of the warning sound stop signal and controlling the warning sound generation means to stop the warning sound after reaching a certain number.

Further, in the present invention, the first radio wave signal is a warning sine actuation signal of a continuous sine wave having a frequency receivable by the electromagnetic coupling means, and the second radio wave signal is generated by the electromagnetic coupling means. An intermittent sine wave warning sound stop signal that repeats a specific code signal at a receivable frequency is used, and the signal identification means counts the wave number of the warning sound actuation signal and reaches the fixed number, and then the warning sound generation means. To generate a warning sound, count the number of coincidences between a code signal that repeats the warning sound stop signal and a preset code signal, and after reaching a certain number, control the warning sound generating means to generate a warning sound. It is intended to provide a warning sound generating device for stopping.

[0014]

With the above arrangement, one electromagnetic coupling means receives the first radio wave signal and the second radio wave signal, and the signal discriminating means discriminates the two signals, so that the first radio wave is detected. When the signal is received, the warning sound generating means emits a warning sound, and when the second radio wave signal is received, the warning sound generating means stops.

The signal identifying means counts the wave number of the warning sound actuation signal and, after reaching a certain number, controls the warning sound generating means to generate a warning sound and counts the intermittent number of the warning sound stop signal. After reaching a certain number, the warning sound generating means is controlled to stop the warning sound.

Further, after the signal identifying means counts the number of waves of the warning sound actuation signal and reaches a certain number, the warning sound generating means is controlled to generate a warning sound, and a code signal in which a warning sound stop signal is repeated and a preset signal are set. The number of coincidences with the generated code signal is counted, and after reaching a certain number, the warning sound generating means is controlled to stop the warning sound.

[0017]

Embodiments of the present invention will be described below in detail with reference to the drawings. The present invention is characterized in that the carrier frequencies of the warning sound actuation signal and the warning sound stop signal are made the same and both signals are received by one resonance circuit (electromagnetic coupling means), and the signal processing circuit in the subsequent stage performs signal discrimination. is there.

First, FIG. 1 shows a circuit block diagram of the warning sound generating apparatus of the present invention. 2 shows signals in each path of the circuit shown in FIG. Each signal of A to K in FIG. 2 represents a signal in each path given the same reference numeral in the circuit of FIG.

The warning sound actuation signal A, which is a continuous sine wave signal at the frequency f1, is converted into a rectangular wave signal B by the comparator 4, the wave number (pulse number) is counted by the counter 9, and when a fixed number n is reached, a signal is given. C is output.

Here, the time until the counter 9 reaches a constant number n and the signal C is output is tn, the time until the signal D is output from the monostable multivibrator 10 is t1, and the monostable multivibrator 11 outputs it. The time until the signal E is output is t2, and the time t until the counter 9 reaches a constant number n and the signal C is output t
A restriction of t2 <tn <t1 is given to n. t1, t2
The relationship of tn is as shown by signals C to E in FIG.

With this configuration, t2 <(n / f
1) <t1 to (n / t1) <f1 <(n / t2), so that the frequency selection characteristic is obtained, and time t1 and time t2
Can be freely set by the signal processing circuit by appropriately setting

Therefore, only when the warning sound actuation signal satisfying t2 <tn <t1 is received, the warning sound actuation control signal F is output from the NAND circuit 12 and the buzzer 8 can be sounded.

The warning sound stop signal A'is a sinusoidal signal A having the same basic frequency f1 as the warning sound actuation signal A and intermittently generated every three waves. After being converted into a rectangular wave signal B ′ by the comparator 4 and passing through the low-pass filter 13 (becomes a signal G), when the counter 14 counts up to a fixed number m, a signal H is output.

Here, the time until the counter 14 reaches a constant number m and the signal H is output is tm, the time until the signal I is output from the monostable multivibrator 15 is t3, and the monostable multivibrator 16 is. When the time from when the signal J is output to the signal J is t4, the time tm until the counter 14 reaches a constant number m and the signal H is output is limited by t4 <tm <t3 and has a frequency selection characteristic. . The relationship between t3, t4 and tm is as shown by signals H to J in FIG.

Therefore, only when the warning sound stop signal satisfying t4 <tm <t3 is received, the warning sound stop control signal K is output from the NAND circuit 17 to stop the buzzer 8.

As described above, by providing the signal discriminating circuit composed of the counter, the monostable multivibrator, the NAND circuit, the low-pass filter and the like, one resonance circuit outputs both the warning sound differential signal and the warning sound stop signal. It becomes possible to receive, and the signal processing circuit can arbitrarily have the frequency selection characteristic. Therefore, malfunctions due to unnecessary radiation and electrostatic noise can be significantly reduced, and an inexpensive and small alarm theft prevention device can be realized.

Needless to say, the time limit can be set not only by the monostable multivibrator but also by an oscillator and a counter, and of course the intermittent number can be freely set according to the system. The reference voltage Vref connected to the comparator 4 is for setting the receiving sensitivity.

Next, another embodiment of the present invention will be described.

FIG. 3 shows a circuit block diagram of this embodiment.
The signals in each path of the circuit block are shown in FIG. 4 as in the previous embodiment. In the embodiment, the warning sound stop signal is an intermittent sine wave (Amplitude Shift) that repeats a code having the same fundamental frequency as the warning sound operation signal.
t Keying) signal.

The warning sound activation signal is a continuous sine wave having a frequency f1, and its signal processing circuit (consisting of the counter 9, the monostable multivibrator 10, the monostable multivibrator 11 and the NAND circuit 12) is exactly the same as that of the above embodiment. Is.

In this embodiment, the warning sound stop signal has a basic frequency f1 and, for example, a 4-bit code "1001" is shown. The warning sound stop signal O received by one resonance circuit 1 is converted into a rectangular wave signal P by the comparator 4, and then serial-parallel converted by the shift register 20 based on the clock signal Q reproduced by the carrier recovery circuit 19 ( Signals R1 to R4) and codes (signals S1 to S1) determined in advance by the designated code setting circuit 22.
The matching circuit 21 determines whether or not it matches with S4). And if the codes are not equal, nothing is output. If the codes are equal, the coincidence output signal T appears every 4 bits. This is counted by the counter 23 in the same manner as in the above-described embodiment, and the time t5 until the monostable multivibrator 24 outputs the signal V with respect to the time tp until the constant number P is reached and the output signal U is output. , T6 <tp <t5 is limited by the time t6 until the monostable multivibrator 25 outputs the signal W.

Therefore, only when the warning sound stop signal satisfying t6 <tp <t5 is received, the warning sound stop control signal X is output from the NAND circuit 26 and the buzzer 8 can be stopped.

With this configuration, it is resistant to malfunction, not only one resonance circuit for reception is provided, but also the warning sound stop signal can be made different depending on the code. Therefore,
For example, the warning sound stop signal can be changed for each store to enhance security, and the warning sound actuation signal can be identified by a code with the same configuration.

[0034]

As described above in detail, according to the present invention, the first radio wave signal is received to generate the warning sound, and the second sound signal is generated.
In the warning sound generating device configured to stop the warning sound by receiving the radio wave signal of No. 1, a single electromagnetic coupling means for receiving the first and second radio wave signals and the electromagnetic coupling means Since the signal identifying means for identifying the signal and the alert sound generating means for producing the alert sound according to the output of the signal identifying means are provided, the possibility of malfunction of the alarm sound actuation and stop signal due to electromagnetic waves is extremely low. A system capable of transmitting and receiving can be constructed at low cost, which is extremely useful.

[Brief description of drawings]

FIG. 1 is a circuit block diagram showing a configuration of an alarm sound generator of the present invention.

FIG. 2 is a diagram for explaining the operation of the present invention.

FIG. 3 is a circuit block diagram showing a configuration of a warning sound generator according to another embodiment of the present invention.

FIG. 4 is a diagram for explaining the operation of another embodiment of the present invention.

FIG. 5 is a circuit block diagram showing a configuration of a conventional warning sound generator.

[Explanation of symbols]

 1 Resonance Circuit 2 Resonance Circuit 3 AC / DC Converter 4 Comparator 5 Switch 6 Lock Hold Circuit 7 Driver Circuit 8 Driver Circuit 9 Counter 10 Monostable Multivibrator 11 Monostable Multivibrator 12 NAND Circuit 13 Low Pass Filter 14 Counter 15 Monostable Multivibrator 16 monostable multivibrator 17 NAND circuit 18 driver circuit 19 carrier recovery circuit 20 shift register 21 coincidence circuit 22 designated code setting circuit 23 counter 24 monostable multivibrator 25 monostable multivibrator 26 NAND circuit

Claims (3)

[Claims] 1. A warning sound generation device configured to receive a first radio wave signal to generate a warning sound, and to receive a second radio wave signal to stop the warning sound, wherein A single electromagnetic coupling means for receiving the second radio wave signal, a signal identifying means for identifying the signal received by the electromagnetic coupling means, and a warning sound generating means for producing a warning sound according to the output of the signal identifying means. And a warning sound generation device. 2. The first radio wave signal is a continuous sine wave warning sound actuation signal having a frequency receivable by the electromagnetic coupling means, and the second radio wave signal is receivable by the electromagnetic coupling means. With a warning sound stop signal having an intermittent sine frequency, the signal identifying means controls the warning sound generating means to generate a warning sound after counting the number of waves of the warning sound actuating signal and reaching a certain number. 2. The warning sound generating device according to claim 1, wherein the warning sound generating means is controlled to stop the warning sound after counting the intermittent number of the warning sound stop signal and reaching a certain number. 3. The first radio wave signal is a continuous sine wave warning sound actuation signal having a frequency receivable by the electromagnetic coupling means, and the second radio wave signal is receivable by the electromagnetic coupling means. As a warning sound stop signal of an intermittent sine wave that repeats a specific code signal at a frequency, the signal identification means counts the wave number of the warning sound actuation signal and controls the warning sound generation means after reaching a certain number. To generate a warning sound, count the number of coincidences between the code signal repeating the warning sound stop signal and a preset code signal, and after reaching a certain number, control the warning sound generating means to stop the warning sound. The warning sound generating device according to claim 1, wherein