JPS6256989B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a short-distance detection sensor that utilizes the reception characteristics of a super-regenerative radio receiver, and its first purpose is to oscillate a quenching oscillator circuit using the energy of received input only at short distances. The second purpose is to make the quenching oscillation circuit easier to control, and the third purpose is to improve the sensitivity of the operation and increase the response speed. The fourth purpose is to have a simple and inexpensive configuration, and a fourth purpose is to ensure reliable control of the quenching oscillation circuit.

As a conventional short-distance detection sensor, for example, there is a sensor using a magnetically sensitive reed switch.
That is, when the magnet Mg is moved from point A to point B as shown in FIG. 1, the reed pieces of the reed switch Ls are magnetized by the magnet Mg and are attracted to each other and come into contact with each other. By the way, the reed switch Ls has disadvantages in that the distance it operates after detecting the magnet Mg is usually about 40 mm, which is very small, as shown in FIG. 2, and its response frequency is about 200 Hz, which is very slow.

The present invention has been made in view of this point, and will be explained in detail below with reference to Examples.

The basic element of the present invention is a super regenerative radio receiver, and the configuration and operation of a general example of this super regenerative radio receiver will be explained.

As shown in Fig. 3, the super regenerative radio receiver includes an antenna 1, a super regenerative front end (hereinafter referred to as front end) 2, a low frequency amplifier 3, a band pass filter 4, a signal level discrimination circuit 5, a buzzer, etc. It is composed of a display device 6. As shown in FIG. 4, the front end 2 is comprised of a buffer amplifier 7, a quenching oscillation circuit 8, and a low-pass filter 9, and this specific circuit is constructed as shown in FIG. Figures 6 a to c are voltage waveform diagrams at points A to C in Figure 5 when no signal input is present, and Figures 7 a to c are voltage waveform diagrams at points A to C in Figure 5 when signal input is present. FIG.

Now, the reception input received by antenna 1 is as shown in Figure 7a, and this signal voltage is
It is amplified by the buffer amplifier 7 shown in the figure, mixed with the quenching output voltage in the quenching oscillator circuit 8 which produces an output as shown in FIG. is converted to This low frequency signal is amplified by the low frequency amplifier 3, but since this output actually includes noise, the band pass filter 4 distinguishes the signal from the noise. The signal component selected by the bandpass filter 4 is converted into a DC voltage corresponding to the amplitude by the signal level discrimination circuit 5, and if the DC voltage level is larger than the set value, it is considered to be a regular signal and is If the signal is, it is displayed on the display 6.

Next, in FIG. 5, the Balfour amplifier 7
is a grounded base type tuned amplifier, which forms a tuned circuit with coil _L1 and capacitor _C4 , and resonates with the carrier frequency of the input radio wave. Resonant output is a coupling capacitor
It is connected to the collector of the transistor Q ₂ in the quenching oscillation circuit 8 by C ₇ . A capacitor _C10 is connected between the collector and emitter of transistor _Q2 to form an oscillation loop of a positive feedback oscillation circuit.
The oscillation principle of this quenching oscillation circuit 8 is as follows.

Assume that the transistor _Q2 is now in a transition state from the on state to the off state. At this time, the collector potential of transistor Q ₂ increases at a constant time constant by an integrating circuit formed by capacitor C ₆ and resistor R ₅ . This change in collector potential is caused by the capacitor
It is transmitted by C ₁₀ to the emitter of transistor Q ₂ . Then, when the collector potential reaches its peak,
In other words, when the current flowing through the oscillation coil _L3 becomes minimum, the back electromotive force of the oscillation coil _L3 generates a bias voltage at the base of the transistor _Q2 in the direction of turning on the transistor _Q2 . ₂ turns on quickly. When turned on, the oscillation coil L ₃ generates a back electromotive force in the direction of turning off the transistor Q ₂ , turning off the transistor Q ₂ , and the collector potential gradually rises due to the integrating circuit consisting of the capacitor C ₆ and the resistor R ₅ do. In this way, transistor _Q2 repeats the on and off oscillation states. In response to the on/off operation of the transistor _Q2 , a transient voltage and current are generated in the tuned circuit composed of the capacitor _C9 and the coil _L2 .
In this state, the resonant output of the buffer amplifier 7 at the previous stage is input to this tuning circuit, and a kind of mixing is performed. As a result, the resulting modulated signal is detected by the low-pass filter 9. The subsequent operations are as described above.

The above operation is performed when the quenching oscillation circuit 8 is in normal operation, that is, in an operating state in which quenching oscillation is maintained. Next, the specific operation of the present invention will be explained. In the short-range detection sensor of the present invention, the bias of the quenching oscillation circuit 8 is set to the point where the quenching oscillation circuit 8 stops oscillating operation, and when the receiving input reaches a certain level, for example, 10 mV, The quenching oscillation circuit 8 starts to generate an oscillation operation due to the energy of the input signal, and a super-regenerative reception output is generated. That is, the reception input level in FIG.
When the voltage is 1 mV or less, for example 100 μV, the signal voltage at point A in Figure 5 will be as shown in Figure 9 a, and the signal voltage at point B in Figure 5 will be as shown in Figure 9 a.
No output is output to point and point C as shown in FIG. 9b and c. Next, as the received input increases, the fifth
The signal voltage at point A in the figure is 10mV as shown in Figure 10a.
When it reaches point B, a signal voltage as shown in FIG. 10b is generated, and at point C, a signal voltage as shown in FIG. 10c is obtained. Therefore, when the reception input is weak, in other words, when the object to be detected is far away, the display 6 does not operate, and when the reception input is strong, in other words, when the object to be detected is at a short distance, the quenching oscillator circuit does not operate. 8 is operated and can be displayed on the display 6.

Next, there are the following four types of means for stopping the oscillation operation of the quenching oscillation circuit 8.
The first means is to use a capacitor as shown in Figure 11.
It changes the time constant of the integrating circuit formed by C ₆ and resistor R ₅ to set the operation of the quenching oscillation circuit 8 to the oscillation stop point.If the capacitor C ₆ is increased, the quenching oscillation circuit 8 stops oscillating. Since the oscillation stops, the value of the capacitor _C6 should be set so that it falls slightly into the oscillation stop region from the constant value at the time the oscillation operation stops. Incidentally, the setting means is constituted by an integrating circuit consisting of the capacitor _C6 and the resistor _R5 . Next, as shown in FIG. 12, the second means is to set the operation of the quenching oscillation circuit 8 to the oscillation stop point by changing the base voltage of the transistor Q ₂ by making the resistor R ₇ variable. Tongista Q ₂
When the base voltage is lowered, the oscillation operation is stopped. Note that the resistor _R7 constitutes a setting means. The third method is to set the oscillation stop point by changing the power supply voltage of the quenching oscillation circuit 8 by changing the resistor _R11 as shown in Fig. 13, and when the power supply voltage is lowered, the oscillation operation is stopped. do. Note that the resistor _R11 constitutes a setting means. Furthermore, the fourth means is to change the time constant of the parallel circuit of capacitor C ₁₂ and resistor R ₈ as shown in FIG.
Decreasing the value of _C12 will stop the oscillation operation.
Note that the setting means is constituted by a parallel circuit consisting of a capacitor _C12 and a resistor _R8 . Therefore, the quenching oscillator circuit oscillates based on the energy of the receiving input only at short distances, making super regenerative reception possible. At this time, the operating distance can reach up to 1 m, and the response speed is as fast as 20 KHz or more. It becomes possible to

In this way, the operating point of the quenching oscillator circuit 8 is set at the point where it transitions from the oscillation _region to the non-oscillation region or when it enters the non-oscillation region by the time constant of the integration circuit connected to the collector of the transistor Q2 of the quenching oscillation circuit 8. By setting the quenching oscillator circuit 8 at the point where the quenching oscillator 8 resistor the base voltage of transistor _Q2
By changing R ₇ and setting the point at which the oscillation region transitions from the oscillation region to the non-oscillation region or the point at which the quenching oscillation circuit 8 enters the non-oscillation region, the quenching oscillation circuit 8 can be easily controlled. By changing the power supply voltage using the resistor _R11 and setting it at the point where the oscillation region shifts to the non-oscillation region or the point where it enters the non-oscillation region, the configuration can be simplified and inexpensive, and furthermore,
In addition, the transistor Q ₂ of the quenching oscillation circuit 8
By changing the time constant of the parallel circuit of capacitor _C12 and resistor _R8 connected to the emitter of 8 can be controlled reliably.

As described above, the present invention includes a super regenerative front end that converts the received input from an antenna into a low frequency signal, and a signal obtained by amplifying the output of the super regenerative front end and passing it through a band pass filter into a DC voltage. A quenching oscillator circuit is provided in the front end of the super regeneration method, and the operating point of the quenching oscillator circuit is set to oscillate. Since the device is equipped with a setting means for setting the point at which the quenching oscillation circuit transitions from the oscillation region to the non-oscillation region or enters the non-oscillation region, the setting means changes the operating point of the quenching oscillation circuit from the oscillation region to the non-oscillation region. By setting the point at the transition point or the point at which the signal enters the non-oscillation region, the quenching oscillation circuit can be oscillated by the energy of the received input only at a short distance to perform detection operation, improving the operation sensitivity and increasing the response speed. It is effective.

[Brief explanation of the drawing]

Fig. 1 is a front view of a conventional short-range detection sensor, Fig. 2 is a characteristic diagram of the same as above, Fig. 3 is a block circuit diagram of an embodiment of a super regenerative radio receiver used in the present invention, and Fig. 4. Figure 5 is a block circuit diagram of the front end of the same super regeneration system as above, Figure 5 is a specific circuit diagram of the same as above, Figures 6 a to c are operation time charts when there is no receiving input as above, and Figures 7 a to c are Operation time chart when the same reception input exists, No. 8
The figure shows the characteristics of the received input and the regenerated received output of the present invention.
9a to 9c are operation time charts when the reception input is weak in the same as above, FIGS. 10a to 10b are operation time charts when the reception input is strong in the same as above, and FIGS. FIG. 2 is a circuit diagram of an embodiment of a quenching oscillation circuit. 1...Antenna, 2...Super regeneration front end, 3...Low frequency amplifier, 4...Band pass filter, 5...Signal level discrimination circuit, 6...Display device, 8...Quenching oscillation circuit, Q ₂ ... Tongister, C ₆ , R ₅ ... Integrating circuit capacitor, resistor, R ₇ ... Resistor, C ₁₂ , R ₈ ... CR parallel circuit capacitor, resistor, E ... Power supply.

Claims (1)

[Claims of Claims] 1. A super-regenerative front end that converts the received input from an antenna into a low-frequency signal, and a signal obtained by amplifying the output of the super-regenerative front end and passing through a bandpass filter and converting it into a DC voltage. and a display device that displays the output of the signal level discrimination circuit, and a quenching oscillation circuit is provided at the front end of the super regeneration method,
A short-distance detection sensor comprising a setting means for setting the operating point of the quenching oscillation circuit to a point at which the quenching oscillation circuit transitions from an oscillation region to a non-oscillation region or a point at which the quenching oscillation circuit enters the non-oscillation region. 2. The setting means is constituted by an integrating circuit connected to the collector of the oscillating transistor of the quenching oscillation circuit, and the time constant of the integrating circuit determines the point or non-oscillating region at which the quenching oscillator circuit shifts from the oscillation region to the non-oscillation region. 2. The short distance detection sensor according to claim 1, wherein the operating point of the quenching oscillation circuit is set at the point where the quenching oscillation circuit enters. 3. A resistor that changes the base voltage of the oscillation transistor of the quenching oscillation circuit is configured as a setting means, and by changing the value of this resistor, the base voltage of the transistor is changed to shift from the oscillation region to the non-oscillation region. 2. The short distance detection sensor according to claim 1, wherein the operating point of the quenching oscillation circuit is set at a point or a point entering a non-oscillation region. 4 A resistor that changes the power supply voltage of the quenching oscillation circuit is configured as a setting means, and by changing the value of this resistance, the power supply voltage of the quenching oscillation circuit is changed and the quenching oscillation circuit shifts from the oscillation region to the non-oscillation region. 2. The short distance detection sensor according to claim 1, wherein the operating point of the quenching oscillation circuit is set at a point where the quenching oscillation circuit enters a non-oscillation region. 5 A parallel circuit of a capacitor and a resistor connected to the emitter of the oscillation transistor of the quenching oscillation circuit is configured as a setting means, and the time constant of this parallel circuit is changed to determine the point or non-oscillation region at which the oscillation region shifts to the non-oscillation region. 2. The short distance detection sensor according to claim 1, wherein the operating point of the quenching oscillation circuit is set at a point where the quenching oscillation circuit enters the oscillation region.