JPH02257726A - Mobile object communication system - Google Patents

Abstract

PURPOSE:To attain high speed communication and to reduce power consumption by supplying power to a data signal reception circuit at a high frequency band, thereby initiating its operation only when the transmission of the data signal is required. CONSTITUTION:A starting signal sent at low speed from the transmission means 11 of a stationary station side is received by a starting signal reception means 21 with the power supply always supplied thereto in a mobile object side communication equipment 2, the starting signal reception means 21 operates a switching means 23 to supply power to a data signal reception means 22 supplying a data with a high frequency band. The transmission means 11 starts the transmission of the data signal at high speed in succession to the starting signal and the data signal is received by the data signal reception means 22 whose operation is started through the supply of power. Since the starting signal is sent at the low speed, the frequency band of the starting signal reception means 21 receiving the starting signal is enough to be low. Thus, high speed data transmission is attained with respect the mobile object side communication equipment 2 and it is possible to reduce the power consumption of the communication equipment 2.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a mobile communication system, and particularly to a communication system that is capable of high-speed communication and that can reduce power consumption of a mobile side communication device.

[Prior Art] Mobile communication systems that perform communication between a communication device (interrogator) installed on a fixed side and a simple communication device (transponder) installed on the mobile side called a tag are attracting attention. For example, an interrogator issues an interrogation signal to a transponder carried by an object or person that comes within its communication range.1. It is used for non-contact recognition of the object or person based on the identification signal returned from the transponder.

In such mobile communication systems, batteries are often used as the power source for the transponders due to their simplicity and light weight, and one challenge is to reduce power consumption and extend battery life.

To solve this problem, power is normally supplied only to the circuits necessary for receiving the interrogation signal, and when the interrogation signal is received, the switch circuit is activated to supply power to the remaining circuits (for example, , Japanese Unexamined Patent Publication No. 61-201177).

[Problems to be Solved by the Invention] By the way, the communication system described in the above publication is intended only for the purpose of identifying transponders and reading data from them, but in recent years, the communication system has been applied to a wider range of fields. Therefore, it has become necessary for the interrogator to issue various command signals instructing the transponder to send out necessary data, or to write various data signals from the interrogator into the memory section of the transponder.

In this case, it is necessary to increase the data transmission speed in order to communicate the necessary commands or data signals in the short time it takes for the transponder to pass through the transponder, but to do this, it is necessary to set the frequency band of the transponder reception section to a high value. necessary, which necessarily means
A problem arises in that the power consumption of the receiving section to which power is constantly supplied increases.

Specifically, in Japanese Patent Application Laid-Open No. 61-201177, it is necessary to constantly supply power to the startup circuit in order to receive the startup signal, but compared to supplying power to the frequency conversion and code conversion circuits, This results in extremely low power consumption.

However, in order to increase the data transmission speed, it is necessary to widen the frequency band of the startup circuit, since the startup circuit that constantly supplies power also serves as an amplification circuit for data signals. Generally, the power consumption of such circuits (start-up circuit, amplifier circuit) increases in proportion to the band frequency, so if the frequency band is widened, the power consumption during standby increases.

SUMMARY OF THE INVENTION The present invention has been made to solve these problems, and an object of the present invention is to provide a mobile communication system that is capable of high-speed data transmission to a mobile side communication device and that can suppress power consumption of the communication device to a low level. shall be.

[Means for Solving the Problems] To explain the present invention in detail, a mobile communication system is composed of a communication device provided on a fixed side and a communication device provided on a mobile side, and the fixed side communication device is provided with a transmitting means for transmitting an activation signal at a low speed, and a transmitting means for transmitting a data signal at a high speed following the activation signal, and the mobile side communication device is constantly supplied with power, and the activation signal is transmitted at a low speed. A start signal receiving means with a low frequency band that receives the signal and operates the switch means, and a data signal receiving means with a high frequency band that starts receiving the data signal when power is supplied by the operation of the switch means. be.

Here, low speed refers to the case where the activation signal is slower than the transmission speed of the data signal, and high speed refers to the case where the activation signal is faster than the transmission speed of the data signal.

Furthermore, a low frequency band means a frequency band in which a low-speed activation signal can be transmitted and received, and a high frequency band refers to a frequency band in which a high-speed activation signal can be transmitted and received.

[Operation] In the communication system configured as described above, the activation signal transmitted at a low speed by the transmitting means of the fixed side communication device is received by the activation signal receiving means of the mobile side communication device, which is constantly supplied with power. When the activation signal reception means receives the activation signal, it operates the switch means and supplies power to the data signal reception means.

The transmitting means starts transmitting a data signal at high speed following the activation signal, and this data signal is received by the data receiving means that is powered and starts operating.

According to this configuration, since the activation signal is transmitted at a low speed, the frequency band of the activation signal receiving means that receives it may be low, and the constant power consumption can be suppressed to a low level. and,
When data communication is required, power is supplied to the data signal receiving means with a high frequency band, and high-speed data transmission is performed.

"Effects of the Invention" As explained above, in the communication system of the present invention, power is normally supplied only to the activation signal receiving circuit in the low frequency band, so the power consumption of the mobile side communication device can be suppressed. Further, only when transmission of a data signal is necessary, power is supplied to the high frequency band data signal receiving circuit and its operation starts, allowing the data signal to be sent to the mobile side communication device at high speed.

In addition, if the startup signal is made slow and the frequency band of the startup signal receiving circuit is sufficiently low, erroneous activation of the responder due to spike noise can be prevented, and it can be used effectively even in harsh environments such as factories. .

[Embodiment] FIG. 1 shows an example in which the present invention is applied to a so-called tag communication system. In the figure, the fixed communication device is an interrogator 1, which is fixedly installed near the production line. The interrogator 1 includes a transmitting circuit 11 that transmits a data signal including an activation signal or a command, the details of which will be described later, a clock generating circuit 12 that applies a predetermined clock to the transmitting circuit 11 to change the signal transmission speed, and the transmitting circuit a modulation circuit 13 that modulates a carrier wave of frequency f1 with a signal sent from 12;
, a transmitting antenna 14 that transmits a modulated wave as an electromagnetic wave, and a transmitting/receiving circuit 15 that emits a second high frequency wave at an unmodulated frequency and extracts a data signal from the high frequency wave that is modulated and returned.
, a transmitting/receiving antenna 16 connected thereto, and a signal processing circuit 17 including a computer.

The mobile body side communication device is a transponder (tag) and is attached to a mobile body such as an assembly part moving on a production line. The responder 2 includes a starting signal receiving circuit 21 for receiving the starting signal, a data signal receiving circuit 22 for receiving the data signal, a switch circuit 23 activated by the starting signal receiving circuit 21, and a signal transmitted from the transmitting antenna 14. a receiving antenna 24 that receives electromagnetic waves, a detection circuit 25 connected to the receiving antenna 24 to detect modulated waves and obtain the activation signal or data signal, a signal processing circuit 26 including a computer, and a storage circuit 27 for storing data. , a transmitting circuit 28 that transmits a data signal including an identification signal, a transmitting/receiving antenna 29 that receives the unmodulated electromagnetic wave of frequency f2, modulates it with a data signal, and sends it back, and a power source 30 such as a battery. .

The power supply 30 is connected to the activation signal receiving circuit 21.
, the switch circuit 23, and the detection circuit 25 are directly connected, and the data signal receiving circuit 22 and the signal processing circuit 26 are directly connected to each other.
, storage circuit 27, and transmission circuit 28 are connected to a power source 30 via the switch circuit 23.

In the communication system configured as described above, the signal processing circuit 17 of the interrogator 1 controls the clock generation circuit 1 by the control signal 17a.
2 is set to a predetermined low frequency, and a start signal is sent to the transmitting circuit 11.

The activation signal is input to the modulation circuit 13 as a pulsed activation signal (FIG. 2 (1)) synchronized with the output clock, and is transmitted from the transmitting antenna 14 as an electromagnetic wave of frequency f1. At the same time, the signal processing circuit 17 activates the transmitting/receiving circuit 15 by the control signal 17b, and operates the transmitting/receiving circuit 15 at the frequency f.
2 unmodulated waves are transmitted from the transmitting/receiving antenna 16.

When the transponder 2 attached to the mobile body reaches the transmission area of the interrogator 1, the receiving antenna 24 picks up the frequency f1.
The electromagnetic waves are received, detected, and input to the activation signal receiving circuit 21 having a low frequency band. The receiving circuit 21 that has received the activation signal issues a switch activation signal to switch the switch circuit 2.
3, thereby each circuit 22, 26, 27
．． Power supply to 28 is started.

The signal processing circuit 26 starts operating and sends an identification signal to the transmitting circuit 28. The transmitting circuit 28 modulates the unmodulated wave reaching the transmitting/receiving antenna 29 with an identification signal and sends it back to the interrogator 1. The interrogator 1 receives the modulated electromagnetic waves through the transmitting/receiving antenna 16, passes through the transmitting/receiving circuit 15, and inputs the identification signal into the signal processing circuit 17.

When the signal processing circuit 17 confirms the identification signal, it issues a control signal 17a to the clock generation circuit 12 again, sets its output clock to a predetermined high frequency, and outputs a data signal to the transmission circuit 11. The data signal is a pulsed data signal synchronized with the above-mentioned high frequency clock output (see Figure 2).
2)) is input to the modulation circuit 13 and sent to the transmitting antenna 14.
It is transmitted as an electromagnetic wave with a frequency f1.

The electromagnetic waves are received by the receiving antenna 24 of the transponder 2,
The detected signal is input to a data signal receiving circuit 22 with a high frequency band, and then reaches a signal processing circuit 26. If the data signal is pure data, the signal processing circuit 26 sends it to the storage circuit 27, and if the data signal is a command, it reads the necessary data signal from a predetermined location in the storage circuit 27. It outputs this to the transmitting circuit 28, modulates an unmodulated wave of frequency f2 with the data signal, and sends it to the interrogator 1 via the transmitting/receiving antenna 29.

At the end of communication, for example, the signal processing circuit 17 of the interrogator 1 sends out a stop signal. This is input to the data signal receiving circuit 22 of the transponder 2 via the antenna 14.24, and the operation of the switch circuit 23 is stopped by the output of the signal processing circuit 26, and the above circuit 26 and each other circuit 22.27 ．．
The power supply to 28 ends.

In the above embodiment, all or part of the functions of the transmitting circuit 11 and the clock generating circuit 12 of the interrogator 1 may be processed by the software of the signal processing circuit 17. Random access memory (RA)
When using M), power is constantly supplied to it.

[Brief explanation of drawings]

FIG. 1 is a block diagram of the overall configuration when the mobile communication system of the present invention is applied to tag communication, and FIG. 2 is a signal time chart 1. 1... Interrogator (fixed side communication device) 11... Transmission circuit (transmission means) 2... Responder (mobile side communication device) 21... Start signal reception times #! ! (Start signal receiving means)
22...Data signal receiving circuit (data signal receiving means) 23...Switch circuit (switching means) Figure 2

Claims (1)

[Claims] It is composed of a communication device installed on the fixed side and a communication device installed on the mobile side. a transmitting means for transmitting a signal, the mobile side communication device is always supplied with power, and a low frequency band starting signal receiving means for receiving the starting signal and activating the switching means; and the switching means. 1. A mobile communication system comprising: data signal receiving means having a high frequency band and which starts receiving the data signal when powered by the operation of the mobile communication system.