JPS61144136A - Data transmitter - Google Patents

Abstract

PURPOSE:To decrease wear of a battery by transmitting intermittently a signal in a data transmitter returning an identification signal to an inquiry radio ware. CONSTITUTION:When an antenna 9 receives a non-modulation inquiry signal transmitted from an ID card or the like, an identification signal transmitted from a coder 10 is modulated by using a diode 12 and retransmitted. A timer circuit 17 has different period depending whether the inquiry signal is received or not. That is, when the inquiry radio wave exists, the period is shorter and when not, the period is made longer. A switch 13 uses an output of the timer 17 to turn on/off an output of the battery and the result is fed to the coder 10. Through the constitution above, the battery consumption is reduced. Since the period of power supply is decreased at the transmission of a response signal, the reception probability of transmission data is improved.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a data sending device for the purpose of returning identification signals and other signals in response to interrogation radio waves sent from an interrogator, such as a so-called ID card. Regarding.

BACKGROUND OF THE INVENTION FIG. 4 shows an example of the configuration of a conventional compensator 1 and a responder 8, in which the unmodulated radio wave (carrier) output of the microwave oscillator 2 is sent to a brancher 2. Bookeylater4. The signal is sent to the transponder 8 via the antenna 5, and in the transponder 8, amplitude modulation is applied to the output of the antenna 9 by applying the variable impedance characteristic of the modulation diode 12 by the output of the encoder 10 driven by the battery 11. Using re-radiation, radio waves are re-transmitted from the antenna 9 towards the antenna 5. The re-radiated output is passed from the antenna 5 through the circulator 4 to the mixer 6 where it is mixed with the output from the splitter 3, homodyne detection is performed, and information from the transponder 8 is taken out from the decoder 7. That is, in this configuration, power is constantly supplied to the battery 11.

FIG. 5 shows a conventional example in which a transponder 8 is provided with an antenna 15 and a detector 14 for detecting radio waves from an interrogator 1, as described in Japanese Patent Application No. 52-28202. , the switch 13 is opened to drive the encoder 10 only when radio waves are emitted from the interrogator 1.

This is a method of obtaining power for the

Problems to be Solved by the Invention However, in the conventional example shown in Fig. %, the battery consumption is rapid;
There was a problem in that the batteries had to be replaced in a short period of time. The present invention solves these conventional problems, and provides a data transmitting device that can reliably respond even with low-power interrogation radio waves, consumes less battery, and can be used for a long time. A timer circuit is installed in the device so that when an interrogation radio wave is detected, power is supplied at a short repeating cycle, and even when no interrogation radio wave is detected, power is supplied at a long repeating cycle.

Therefore, according to the present invention, even if the interrogation radio wave becomes weak due to reflection or the like, there is no situation where there is no response at all, and power consumption can be suppressed to a minimum.

Example FIG. 1 shows an embodiment of the present invention.

In FIG. 1, 9 is an antenna that receives an unmodulated interrogation radio wave from the interrogator 1 and transmits a modulated retransmission radio wave, and 10 is an antenna that encodes data for transmission and sends it to a diode 12 for modulation. 11 is a battery as a power source; 12 is a diode as a type of variable impedance element for modulation; 13 is a switch as a control means for controlling opening/closing of the battery output; 17 is a timer for controlling the switch 13. It is. Figure 2 shows timer 1 in Figure 1.
This is an example of the configuration of No. 7. (G) in Figure 2, 15 is a receiving antenna for detecting the presence or absence of interrogation radio waves, 18
is a diode for rectifying the received radio wave, 19 is a resistor for charging the capacitor with the radio wave output, 20 is a diode for preventing backflow, 21 is a capacitor for charging, 22 is a seamit circuit for shaping the capacitor 21 voltage signal, 23 is a The discharge resistor 24 of the capacitor 21 is an analog switch that is turned ON when the transmission end signal sent from the encoder reaches lHIFgh.

Next, the operation shown in FIG. 2 will be explained using the timing charts shown in FIGS. 3(A) and 3(B). Since the output of diode 18 is 0, the output of capacitor 2 is
Charging to 1 takes place only through diode 20.

Therefore, as shown in ((support) of Figure 3 (5), the resistance 1
The capacitor voltage rises with a time constant determined by 9, and the time tx
After that, the voltage reaches the shield voltage f, and the output (C) of the voltage circuit 22 becomes H/gh. When the output (q) of the seamit circuit 22 becomes Hpg hi, power is supplied to the encoder 10 and a signal is sent. However, after time t2, the signal transmission ends and the end signal becomes Hpg as shown in bl.
When h is reached, the analog switch 24 is turned on, the charge in the capacitor 21 is rapidly discharged through the resistor 23, and the Schmitt output falls to Low. Transmission end signal is LOW
When the voltage drops to , the terminal voltage of the capacitor 21 starts to rise again, and the above operation is repeated. Next, when there is an interrogation radio wave, charging of the converter 21 is performed not only through the diode 20 but also by the rectified current of the interrogation radio wave, so that fal, Q)l in FIG. 3(B).

As shown in IcI, the charging time is a shorter time t'1 than the time h when there is no interrogation radio wave. The subsequent operation is the same as when there is no interrogation radio wave. As described above, according to the embodiment described above, when there is no interrogation radio wave, transmission is performed intermittently at a long repeating cycle, but when there is an interrogation radio wave, the intermittent transmission repeating cycle is shortened.

Note that the reception input for making the period of the timer circuit 17 variable does not necessarily require a separate antenna 15, and the output of the antenna 9 may be rectified and shared.

Effects of the Invention As is clear from the above embodiments, the present invention can reduce battery consumption by transmitting signals intermittently. When this occurs, the probability of receiving the transmitted data can be increased by shortening the repetition period of intermittent transmission.

It also has the advantage that there is no fear that data transmission will not be performed at all even if the interrogation radio wave cannot be detected even though it is within the interrogation area due to reflections from surrounding structures or the like.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a data sending device according to an embodiment of the present invention, Fig. 2 is a circuit diagram showing an embodiment of the timer circuit of Fig. 1, and Fig. 3 (5) and (B) are Fig. 2 FIG. 2 is a timing chart showing the operation of the timer circuit of FIG. 1. Interrogator, 9. Antenna, 1o. Encoder, 11. Battery, 12. Diode. Name of agent: Patent attorney Toshio Nakao (1st person, 2nd person)
Figure 3 Port (A) w43 Figure (a)

Claims (1)

[Claims] an antenna that receives radio waves from an interrogator and retransmits them; a variable impedance element that modulates the retransmitted radio waves; and a coder that creates a modulation code and supplies it to the variable impedance element; The transponder is provided with a power source for driving the encoder, a timer circuit whose repetition period is variable according to the reception input from the interrogator, and a control means for controlling the output of the power source according to the output of the timer circuit, A data transmitting device in which the repetition period of a timer circuit is short when there is an interrogation radio wave and long when there is no interrogation radio wave.