JPH0422227B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION FIELD OF INDUSTRIAL APPLICATION The present invention relates to a device for remotely monitoring the battery status of a device that operates using a battery.

Conventional configuration and its problems Conventionally, in a battery-operated device, as a means of monitoring the battery status, a circuit for battery voltage monitoring is built into the device, and the display is indicated by an indicator such as a voltmeter. The method was commonly used. However, when this method is applied to a system that uses a large number of battery-powered devices, such as a data collection system, a monitoring circuit must be built into each device, which increases the cost of the entire system. In addition, it is necessary to check each device to monitor the battery status, and there is a drawback that central control is difficult.

OBJECTS OF THE INVENTION It is an object of the present invention to provide a battery voltage monitoring device that eliminates the above-mentioned drawbacks and enables centralized management of the battery status of a large number of devices that operate on batteries.

Structure of the Invention The present invention focuses on the fact that the oscillation cycle of a basic timer for setting the periodic contention activation time of a battery-operated communication device slave (hereinafter referred to as slave) fluctuates due to fluctuations in power supply voltage. However, the battery status of each slave unit is centrally managed on the communication device master unit (hereinafter referred to as the master unit) by comparing it with the period of an accurate reference oscillator using a crystal oscillator in the master unit. It is something.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of a wireless information gathering system suitable for implementing the present invention.

In FIG. 1, 1 is a host computer that manages the entire system, 2 is a base unit of a wireless communication device connected to this host computer 1, 3a,
3b, . . . 3c are wireless communication device slave devices, respectively.

This system is configured so that a master unit collects various data from slave units distributed at various locations, and reports the data to a host computer that manages the entire system. In this system, the slave units are installed in various locations or are used in a movable state, so they are each powered by batteries.

Another feature of this system is that it uses a time contention method, which is an improved version of the contention method, to establish a communication path between the parent device and the child device. Here, the time contention method is a method proposed for the purpose of preventing communication collisions caused by multiple handsets calling the base unit at the same time and reducing the power consumption of the handset power supply, as shown in Figure 2. As shown, each slave unit generates a contention call at regular intervals (128 seconds in this embodiment) to establish a communication path with the base unit.

In FIG. 2, A, B, C, and D indicate the communication status of the base unit 2, slave units 3a, 3b, and 3c, respectively. In addition, contention calls are generated at fixed time slots to prevent contention collisions between slave units 3a, 3b, and 3c.

FIG. 3 shows the configuration of the handset.

In the figure, 4 is a timer for activating _contention after a certain period of time as shown in Figure 2, 5 is a sensor for detecting data sent to the base unit, and 6 is a sensor for detecting data sent to the base unit. A battery serves as a power source for the slave unit; 7 is a controller that controls the operation of the slave unit;
8 is a transmission/reception controller that controls communication with the base unit, and 9 is an antenna.

FIG. 5 shows a specific configuration of the timer 4, which is configured using a PUT (programmable union transistor) as the main element. Generally, when constructing a stable oscillation circuit using this element, a circuit is required to compensate for fluctuations in the oscillation period due to fluctuations in the power supply voltage V _CC , but the embodiment shown in Fig. 5 is equipped with a compensation circuit. Without
It is configured so that the power supply voltage affects the oscillation period, which is the original drawback of PUT. The characteristics of the power supply voltage versus oscillation period of this oscillation circuit are as shown in FIG.

Next, the operation of the above embodiment will be explained.
Various information obtained from the sensor 5 of each slave unit is periodically reported to the base unit 2, and the host computer 1
Management will be carried out.

By the way, specifically, it is generated from the timer 4. For example, a pulse with a period of 1.0 seconds is counted a certain number of times by a counter built into the slave unit controller 7.
It is configured to generate a contention call at the time when 128 times have been counted. Therefore, due to fluctuations in the power supply voltage, the oscillation period of timer 4 becomes 1.0.
When changing from seconds to 1.1 seconds, the contention period changes from 128.0 seconds to 140.8 seconds.

On the other hand, the base unit is equipped with a high-precision timer/counter using a crystal oscillator, which measures the time interval between the slave unit's previous contention call and the current contention call. It is possible to detect variations in the oscillation cycle of the timer 4.

Furthermore, the battery voltage of the slave unit is detected by associating the oscillation characteristics of the timer 4 in the slave unit with a table based on the power supply voltage vs. oscillation cycle characteristics shown in Figure 4 in the base unit 2 or host computer 1. It is possible to do so.

Note that in the above embodiment, the present invention is applied to a system using wireless, but it is also possible to apply the present invention to a distributed communication system.

Effects of the Invention As is clear from the above explanation, according to the present invention, it is possible to monitor the battery voltage of the slave unit in the base unit or the host computer without using a special circuit for detecting the battery voltage of the slave unit. Therefore, it is possible to centrally manage the battery voltage of all slave devices, and it is also possible to reduce the cost of the entire system.

[Brief explanation of drawings]

Figure 1 is a block diagram of a wireless communication system, Figure 2 is a block diagram of a wireless communication system.
The figure is a contention timing diagram of the time contention method of the same system, Figure 3 is a block diagram of a wireless communication device slave unit using a battery voltage monitoring device according to an embodiment of the present invention, and Figure 4 is a diagram of a timer. The power supply voltage vs. oscillation period characteristic diagram, FIG. 5, is a circuit diagram of the timer. 1...Host computer, 2...Base unit, 3
a, 3b, 3c...Slave unit, 4...Timer.

Claims (1)

[Claims] 1. Each slave unit operated by a battery is provided with a timer for a contention call in which the period of an output signal changes depending on the voltage fluctuation of the battery, and the master unit communicating with each slave unit is provided with a timer for the contention call. A battery voltage monitoring device comprising means for detecting the voltage of a battery of each slave unit by detecting a change in the cycle of the battery voltage monitoring device.