JPH04281595A - Feeding method to hand-held terminal - Google Patents

Abstract

PURPOSE:To enable a hand-held terminal to be used a long time by operating the hand-held terminal without performing charge on a built-in battery and the exchange of a battery, etc., and to save time and labor for the charge of the built-in battery and the exchange of the battery, etc. CONSTITUTION:An instrumentation system which performs communication between the hand-held terminal 4 and a sensor 1 connected to a transmission line 2 for instrumentation by connecting the hand-held terminal 4 in parallel with the sensor 1 is provided with a feature that the output current of the sensor 1 can be corrected by issuing a correction command from the hand-held terminal 4 and the hand-held terminal 4 can be operated setting a corrected current as a power source.

Description

[Detailed description of the invention]

[Object of the invention]

0002

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for supplying power to a handheld terminal, which is applied when supplying power to a handheld terminal.

0003

2. Description of the Related Art In a handheld terminal used by being connected to a 4-20 mA transmission line for instrumentation, a built-in battery provided within the handheld terminal supplies the power required for its operation.

0004

[Problems to be Solved by the Invention] However, with this power supply method, all the power must be provided by the built-in battery, so the operating time is limited by the capacity of the built-in battery, and the built-in battery must be periodically recharged. Not only does it take a lot of effort to charge the battery and replace it, but the voltage of the built-in battery sometimes drops during use, making it unusable.

[0005] In view of the above circumstances, the present invention enables a handheld terminal to be operated without charging the built-in battery or replacing the battery, thereby allowing the handheld terminal to be used for a long period of time. The purpose of this invention is to provide a method of supplying power to a handheld terminal that can save the trouble of charging the built-in battery and replacing the battery.

[Configuration of the invention]

[0007]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a method for supplying power to a handheld terminal by connecting the handheld terminal in parallel with a sensor connected to an instrumentation transmission line. and the sensor, the handheld terminal outputs a correction command to correct the output current of the sensor, and operates the handheld terminal using the corrected current as a power source. It is characterized by

[0008]

[Operation] In the above configuration, a correction command is output from the handheld terminal to correct the output current of the sensor,
By operating the handheld terminal using this corrected current as a power source, the handheld terminal can be operated without charging the built-in battery or replacing the battery, thereby allowing the handheld terminal to be used for a long time. , saving you the trouble of charging the built-in battery and replacing the battery.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing an example of a control system to which an embodiment of the method of supplying power to a handheld terminal according to the present invention is applied.

The control system shown in this figure includes a sensor 1,
It is equipped with a 4-20mA transmission line 2, a load resistor 3, a handheld terminal 4, and a connection cable 5, and the handheld terminal 4 issues a command to correct the output current to the sensor 1 and outputs it from the sensor 1. The handheld terminal 4 is continuously operated by the corrected current.

The sensor 1 detects the state of the equipment to be measured, converts the detection result into a current signal, sends it onto the transmission line 2, and transmits it to the load resistor 3 connected to the transmission line 2 and the handheld terminal. 4.

As shown in FIG. 2, the handheld terminal 4 is charged using a switch 6 that cuts off the current supplied via the connection cable 5, and the current supplied via the switch 6 and the connection cable 5 as a power source. When the charging circuit 9 and the switch 6 are open, the charging circuit 9 operates using the current supplied from the charging circuit 9, and when the switch 6 is closed, the switch 6 and A main circuit 8 that operates using the current supplied via the connection cable 5 as a power source, a switch 7 that cuts off the current supplied via the switch 6, and when the switch 7 is in a closed state, A load resistor 10 that operates as a load, and the connection cable 5
and the input/output terminals of the main circuit 8.

When using the handheld terminal 4, first, the handheld terminal 4 and the transmission line 2 are connected by the connection cable 5 with the switches 6 and 7 both open.

Thereafter, the main circuit 8 is operated by the power of the charging circuit 9, and an output current correction command is sent to the sensor 1.

As a result, when the current output from the sensor 1 changes from "IS" to "IS + IH", the switch 6 is closed and the increased current "IH" starts the continuous operation of the main circuit 8. , the remaining current is supplied to the charging circuit 9 to charge it.

At this time, the switch 7 is appropriately closed to prevent the charging circuit 9 from being overcharged.

As described above, in this embodiment, an output current correction command is issued from the handheld terminal 4 to increase the current output from the sensor 1, and the handheld terminal 4 is continuously operated using this increased current. Therefore, the handheld terminal 4 can be operated without charging the built-in battery or replacing the battery.This allows the handheld terminal 4 to be used for a long time, and it is also possible to operate the handheld terminal 4 without charging the built-in battery or replacing the battery. You can save time and effort.

Furthermore, in the embodiment described above, the current output from the sensor 1 is increased by the correction command output from the handheld terminal 4, but as shown in FIG. When the sensor 1 is operated based on the current output from the power supply 12, a correction command is issued from the handheld terminal 4 and the current supplied to the sensor 1 is changed to "IS".
” to “IS-IH” and the current decrease “IH” at this time is supplied to the handheld terminal 4 to operate it.

Furthermore, in each of the embodiments described above, when a correction command is issued from the handheld terminal 4 and the current on the transmission line 2 changes, the switch 6 is closed to start continuous operation of the main circuit 8. However, as shown in FIG. 4, after issuing a correction command from the handheld terminal 4, the operation of each device (not shown) connected to the transmission line 2 is prohibited for a predetermined period T, and the output of the sensor 1 is disabled. In this state, the current output from the sensor 1 and the current consumed by the sensor 1 are corrected, and the handheld terminal 4 takes in the corrected current, and the main circuit 8
The continuous operation may be started.

By doing this, even if the timing at which the current output from the sensor 1 or the current consumed by the sensor 1 is corrected and the timing at which the corrected current is taken in by the handheld terminal 4 are slightly different, ,
It is possible to prevent each device from malfunctioning.

[0021]

[Effects of the Invention] As explained above, according to the present invention, the handheld terminal can be operated without charging the built-in battery or replacing the battery, thereby making it possible to use the handheld terminal for a long time. This also saves you the trouble of charging the built-in battery and replacing the battery.

[Brief explanation of the drawing]

FIG. 1 is a block diagram illustrating an example of a control system to which an embodiment of the method of supplying power to a handheld terminal according to the present invention is applied.

FIG. 2 is a block diagram showing a detailed circuit example of the handheld terminal shown in FIG. 1;

FIG. 3 is a block diagram showing an example of a control system to which another embodiment of the method of supplying power to a handheld terminal according to the present invention is applied.

FIG. 4 is a timing diagram illustrating another embodiment of the method for supplying power to a handheld terminal according to the present invention.

[Explanation of symbols]

1 Sensor 2 Transmission line 4 Handheld terminal 5 Connection line 6, 7 Switch 8 Main circuit 9 Charging circuit 10 Load resistance 11 Transformer

Claims (1)

[Claims] Claim 1: In an instrumentation system in which a handheld terminal is connected in parallel to a sensor connected to an instrumentation transmission line and communication is performed between the handheld terminal and the sensor, a correction command is output from the handheld terminal. A method for supplying power to a handheld terminal, comprising: correcting the output current of the sensor, and operating the handheld terminal using the corrected current as a power source.