JPS6025465A - Battery voltage monitoring device - Google Patents

Abstract

PURPOSE:To monitor at a remote position for respective battery states of many devices which operate with batteries by detecting the variation in period of a contention call which fluctuates with the voltage fluctuation of batteries. CONSTITUTION:Various kinds of information obtained by sensors 5 of respective slave equipments are reported periodically to a master equipment 2, and a host computer 1 controls them. At this time, a contention call is generated when the counter incorporated in a slave equipment controller 7 counts the specific number of pulses with a 1.0 second period generated by a timer 4. Therefore, when the oscillation period of the timer 4 varies with the voltage of a battery 4, the contention also varies in period. The master equipment 2, on the other hand, is equipped with a high-precision timer counter, and the time interval between the last contention call and current contention call of the slave station is measured to detect the variation in oscillation period of the timer 4 in the slave station, detecting the battery voltage of the slave equipment.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention 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, as a means of monitoring the state of the battery in a device that operates on a battery, a battery voltage monitoring circuit is built into the device and displayed using an indicator such as a voltmeter. 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 acquisition system, a monitoring circuit must be built into each device, which increases the cost of the entire system. Furthermore, it is necessary to check each device in order to monitor the battery condition, and there is a drawback that it is difficult to centrally manage the battery.

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 allows central control of the battery status of a large number of devices that operate on batteries.

Composition of the Invention The present invention provides a basic timer for setting the periodic contention activation time of a communication device slave unit (hereinafter referred to as slave unit) that operates on a battery, in which the oscillation cycle fluctuates due to fluctuations in the power supply voltage. By focusing on the frequency of the accurate reference oscillator using the crystal oscillator in the residual layer, the battery status of each slave device can be centrally managed on the communication device equipment side (hereinafter referred to as the residual layer). This is what I did.

Description of examples Embodiments of the present invention will be described below with reference to the drawings.

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

In Figure 1, 1 is the host that manages the entire system.
A computer 2 is a wireless communication device base unit 3a connected to the host computer 1.

3b, . . . 3C are respective wireless communication device base units.

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, slave units are installed in various places or are used in a movable state, so each unit is powered by a battery.A feature of this system is the time continuance controller, which is an improved contention method. A communication path is established between the base unit and the slave unit using this method. Here, the time contention method is a method proposed for the purpose of preventing communication conflicts 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 handset generates a contention call at regular intervals (128 seconds in this embodiment) to establish a communication path with the base.

In FIG. 2, numbers 42, /, and 2 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 the continuation/gn of the slave units sa, 3b, and sc from colliding with each other.

FIG. 3 shows the configuration of the handset.

In the same figure, as shown in Figure 2-2 of 4fd, a timer is used to start the contention after a certain period of time, 6 is a sensor for detecting data sent to the parent device, and 6 is a slave device. A battery serves as a power source for the device; 7 is a controller that controls the operation of the child device; 8 is a transmission/reception controller that controls communication with the parent device; and 9 is an antenna.

FIG. 6 shows the specific configuration of the timer 4,
It is configured using a PUT (programmable unijunction 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 vcc, but the embodiment shown in FIG. 6 does not include a compensation circuit. The structure is such that the influence of the power supply voltage on the oscillation period, which is the original drawback of PUT, occurs. The characteristics of the power supply voltage versus oscillation period of this oscillation circuit are shown in FIG.

Next, the operation of the above embodiment will be explained.

Various information obtained by the sensor 6 of each slave unit is periodically reported to the base unit 2 and managed by the host computer 1.

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

On the other hand, the main unit is a high-precision timer using a crystal oscillator.
Equipped with a counter, it is possible to detect fluctuations in the oscillation cycle of the timer 4 in the slave unit by measuring the time interval between the previous contention call, cold call, and current contention write call of the slave unit.

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 units, and it is also possible to reduce the cost of the entire system.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a wireless communication system, Fig. 2 is a contention timing diagram of the time contention method of the same system, and Fig. 3 is a wireless communication system using a battery voltage monitoring device according to an embodiment of the present invention. A block diagram of the communication device handset, Fig. 4 is a timer power supply voltage vs. oscillation period characteristic diagram, Fig. 6
The figure is a circuit diagram of the same timer. 1... Host recomputer, 2...
Master unit, 3a, 3b, 3c...Slave unit, 4...
··timer. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 Figure 3 Figure 4 Memorandum, Voltage (V) Figure 5

Claims (1)

[Claims] Each slave device that operates on a battery is provided with a timer for contention calls whose output signal period changes depending on the voltage fluctuation of the battery, and the master device that communicates with each slave device is provided with a timer for the contention call period that changes depending on the voltage fluctuation of the battery. A battery voltage monitoring device comprising means for detecting the battery voltage of each slave device by detecting a change.