JPH09219222A - Battery residual capacity indicator for communication equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To automatically make correction for the deviation of residual capacity indication resulting from a change in battery internal resistance, or the use of a battery different from a dedicated battery, and indicate such battery residual capacity as corresponding to the battery internal resistance, in the case of using the battery for portable communication equipment to transmit and receive a signal on a time sharing basis. SOLUTION: A ROM 30 contained in a microcomputer 8 stores three threshold value tables 3 established for a dedicated battery 20 so as to correspond to the resistance of a battery part 5, and one threshold value table for a battery pack. When a power switch 9 is turned on, the voltage levels N1 and N2 of the battery part 5 in no-load and load conditions are measured to calculate a parameter (N1-N2). Then, one table is selected from the four threshold value table, depending on the value of the parameter (N1-N2). Thereafter, the level, of residual capacity is judged and indicated by use of the selected threshold value table.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery level indicator for determining and displaying the level of a battery used as a power source in a communication device such as a digital mobile phone.

[0002]

2. Description of the Related Art As a power source for a mobile phone, it is required to have excellent portability and to be used for a long time. Generally, a nickel-cadmium battery (NiCd battery), a nickel-hydrogen secondary battery, or a lithium-ion battery 2 is required. Secondary batteries are often used. Further, there is also a battery pack in which a dry battery or the like different from the dedicated battery is used as a power source.

Most of such mobile phones are provided with a battery level indicator for displaying the level of the level of the battery being used on an LCD or the like. As a result, the user can charge the battery or replace the battery when the battery level becomes low, and it is possible to prevent the malfunction of the battery due to insufficient battery capacity during communication. A battery remaining amount indicator provided in a mobile phone generally has a voltage detection circuit for detecting the voltage of the battery to constantly detect the voltage of the battery. Then, the detected voltage is compared with a threshold value table determined based on the discharge characteristics of the dedicated battery used in the mobile phone to determine the remaining battery level,
It is designed to be displayed on a display unit such as an LCD. Normal,
In the threshold table, a plurality of voltage thresholds are set stepwise, and the remaining battery level is displayed in several steps.

By the way, in a digital cellular type mobile phone, communication is performed by a TDMA method (time division multiple access method). In the type in which transmission / reception is performed in a time division manner such as the TDMA method, current consumption is considerably different between the reception period and the transmission period during communication. That is, in the reception period, a relatively small current is stably consumed, whereas in the transmission period, a relatively large current is consumed due to amplification of an amplifier and the like, and the consumed current of the wireless environment is It fluctuates due to fluctuations. Then, the voltage drop of the battery becomes maximum at the maximum current during the transmission period.

Therefore, in the case of such a communication method, in setting the above voltage threshold, it is possible to know the time when the battery voltage at the maximum current of the transmission period reaches the minimum necessary voltage for communication. It is preferable to set.
However, as described above, the battery voltage during transmission fluctuates with changes in the wireless environment.Therefore, if the judgment is made using the battery voltage value sampled during transmission, the judgment result fluctuates and the remaining battery level is displayed. It becomes unstable. Therefore, conventionally, a determination method of sampling the battery voltage at the time of reception and using a voltage threshold set in consideration of the voltage drop at the time of maximum current at the time of transmission compared to the time of reception has been adopted. Depending on the method, a stable determination of the remaining amount level is made.

[0006]

However, in a battery level indicator which measures the level of battery level using such a method, the voltage threshold is usually set based on the characteristics of a relatively new dedicated battery. Therefore, for example, when the dedicated battery deteriorates and the internal resistance increases, when a dry battery with a large internal resistance is used, or when the contact resistance between the battery and the battery terminal changes, there is a gap in the determination. Will occur.

That is, if the internal resistance of the battery actually used is larger than the internal resistance assumed at the time of setting the voltage threshold value, the voltage drop at the time of maximum current at the time of transmission becomes large accordingly. Despite the fact that the remaining battery level is displayed as appropriate, the voltage at the time of transmission may actually fall below a specified value, causing a problem in communication.

It is considered that such a problem is common not only to a TDMA type mobile phone but also to a battery level indicator used in a portable communication device in which transmission and reception are performed in a time division manner. In view of the above problems, the present invention provides a battery level indicator used in a portable communication device in which transmission and reception are performed in a time division manner, when the internal resistance of the dedicated battery changes or when a battery different from the dedicated battery is used. The purpose of the present invention is to automatically correct the deviation of the remaining battery level display in, and to accurately display the remaining battery level adapted to the internal resistance of the battery.

[0009]

In order to achieve the above object, the invention according to claim 1 is a battery level indicator in a portable communication device for performing transmission / reception in a time division manner, the detection being for detecting a battery voltage. Means for measuring a parameter corresponding to the internal resistance of the battery on the basis of the battery voltage detected during the first load and the battery voltage detected during the second load; Having a plurality of tables provided in advance, table means indicating the remaining battery level corresponding to the possible battery voltage value, selecting means for selecting the table corresponding to the measured parameter, according to the selected table, It is characterized in that it is provided with a determination means for determining the remaining battery level corresponding to the battery voltage detected by the detection means, and a display means for displaying the determined remaining battery level on the display unit.

The internal resistance of the battery mentioned here includes not only the internal resistance of the battery itself but also the contact resistance between the battery and the battery terminal. According to this configuration, the parameter of the internal resistance of the battery is measured by the measuring means.
Then, the selection unit selects a table according to the internal resistance of the battery from the plurality of tables included in the table unit based on the measured parameters.

Therefore, the determining means can accurately determine the remaining battery level by using the table adapted to the internal resistance of the battery. In the invention described in claim 2, in contrast to the invention described in claim 1, the measuring means measures the difference between the battery voltage under the first load and the battery voltage under the second load as a parameter. I am trying.

According to a third aspect of the present invention, in contrast to the second aspect of the invention, the first load is in a state immediately after the portable communication device is powered on, and the second load is the portable communication device. The backlight LED for illuminating the display section is illuminated. In this case, the measuring unit can measure the parameter by using the state of the portable communication device immediately after the power is turned on.

The invention according to claim 4 is different from the invention according to claims 1 to 3 in that the display means displays the remaining battery level in multiple stages, and the table means displays the battery voltage value for each parameter of a predetermined width. It is characterized by having a plurality of tables holding thresholds for determining which of the multi-stage battery levels corresponding to the above.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a digital mobile phone according to an embodiment of the present invention, and mainly shows a configuration of a portion corresponding to a battery level indicator incorporated therein.

The digital mobile phone 1 performs communication by the TDMA system, and as shown in FIG. 1, an antenna 2 for transmitting and receiving a high frequency signal to and from a base station,
The reception circuit unit 3 having various functions for reception, the transmission circuit unit 4 having various functions for transmission, the battery unit 5 provided as a power source, and the voltage of the power supplied from the battery unit 5 to each unit Converting voltage regulator 6 and battery unit 5
A / D converter 7 for measuring the voltage of the battery and outputting it as a digital signal, a microcomputer 8 for controlling each part, and a power switch 9 for turning on / off the power supply from the battery part 5.
And an LCD that displays the remaining battery level of the battery unit 5, etc.
10 and L functioning as a backlight for various operation keys
It is composed of an ED 11 and the like.

The receiving circuit section 3 frequency-converts the high-frequency signal received from the antenna 2 and performs processing such as modulation / demodulation TDMA, and sends the received control signal to the microcomputer 8 and outputs a voice signal from a speaker (not shown). . Transmission circuit unit 4
Performs processing such as modulation TDMA on a voice signal input from a microphone (not shown) and a control signal from the microcomputer 8, converts the signal into a high frequency signal, and transmits the high frequency signal from the antenna 2.

A dedicated battery 20 (lithium ion battery having a nominal voltage of 3.6 V) is stored in the battery section 5.
The positive electrode terminal 5a and the negative electrode terminal 5b of the battery unit 5 are in contact with the positive electrode and the negative electrode of the dedicated battery 20, and the positive electrode terminal 5a
Is connected to the voltage regulator 6, and the negative terminal 5b side is G
Grounded to ND. Further, the positive electrode terminal 5a is connected to the A / D converter 7 via the voltage dividing circuit 7a, and the voltage signal of the battery unit 5 is reduced by a predetermined ratio to allow the A / D converter 7 to operate.
To be entered.

Although not shown in the drawing, a battery pack (nominal voltage of 4.5V) containing three 1.5V alkaline dry batteries can be connected to the battery section 5, and the remaining amount of the dedicated battery 20 is maintained. Even if there is no battery, the connected battery pack can be used as a power source. The voltage regulator 6 converts the electric power supplied from the battery unit 5 into a predetermined voltage (3.1 V) to receive the receiving circuit unit 3, the transmitting circuit unit 4, the microcomputer 8, the LCD 10, the LE.
It is supplied to each part such as D11.

The A / D converter 7 compares the voltage signal from the battery unit 5 with a predetermined voltage signal (3.1 V) input from the voltage regulator 6 to constantly maintain the voltage value of the battery unit 5. It measures, converts the measured value into a digital signal, and sends it to the microcomputer 8. The microcomputer 8 controls the operation of the receiving circuit unit 3 and the transmitting circuit unit 4, samples the voltage signal from the A / D converter 7 and determines the remaining battery level, L
The CD 10 display control, the LED 11 lighting control, and the like are performed.

Further, the ROM 30 provided in the microcomputer 8
Stores a threshold table used for determining the remaining battery level. In the present embodiment, the three threshold value table Nos. 1 to 3 (see Table 1) and one threshold value table No. 1 for the battery pack. 4 (see Table 2) are stored. A remaining amount level display unit 40 is provided in the LCD 10. This remaining level display section 40
Can display up to 8 marks in units of 2.

The number of marks displayed on the remaining level display section 40 is controlled by the microcomputer 8 so that the battery section 5
As the remaining battery level decreases to L4 → L3 → L2 → L1 (see FIG. 3), it gradually changes from 8 → 6 → 4 → 2, and the voltage of the battery unit 5 is required for communication. After reaching the lowest level limit voltage P0 (3.2 V, see FIG. 3) (remaining level E), all marks disappear. The operator can check the remaining level display 4
By looking at the display of 0, the remaining battery level can be known.

If the battery voltage falls below the limit voltage P0, the communication function may be hindered. Therefore, the microcomputer 8 constantly monitors whether the voltage signal from the A / D converter 7 is equal to or higher than the limit voltage P0. However, when the voltage drops below the limit voltage P0, a warning sound is emitted to notify the operator. The LED 11 is the LCD 10 and the power switch 9
It is provided as a backlight for various operation keys,
Series resistor 12 for adjusting brightness is connected,
When the LED 11 is turned on, a substantially constant current (200 mA)
Is about to flow. This LED 11
The lighting control is performed by the microcomputer 8, and the lighting is performed for about 10 seconds immediately after the power switch 9 is turned on.

(Description of Operation of Digital Mobile Phone 1) Next, the operation of the digital mobile phone 1 performed under the control of the microcomputer 8 will be described. When the power switch 9 is ON, the digital mobile phone 1 operates in one of two modes, a communication mode and a standby mode, and the mode selection is made based on an instruction from the operator. It

FIG. 2A is a time chart showing the battery voltage waveform in the communication mode, and FIG. 2B is a time chart showing the battery voltage waveform in the standby mode. In the figure, Tx represents a transmission period, Rx represents a reception period, and I represents an idle period. One scale in the vertical direction represents 100 mV, and one scale in the horizontal direction is 20 msec in (A),
(B) represents 100 msec.

In the communication mode, the microcomputer 8
The RxON signal and the TxON signal are issued at the timing of the reception time slot and the transmission time slot of the DMA frame, and the reception circuit unit 3 and the transmission circuit unit 4 are alternately operated to perform the transmission / reception operation. And FIG.
As shown in (A), at a cycle of 20.0 msec,
Control signals and voice signals are exchanged with the base station while repeating transmission and reception.

On the other hand, in the standby mode, the microcomputer 8 issues an RxON signal every 720 msec period to intermittently operate the receiving circuit section 3 to receive a control signal from the base station. Here, the power consumption in the battery unit 5 in both modes will be considered. In the communication mode, during the reception period Rx, the reception circuit unit 3 receives the transmission period T.
To x, the power from the battery unit 5 is supplied to the transmission circuit unit 4 through the voltage regulator 6. Along with this, in the transmission period Tx, the battery unit 5 starts from 500 mA.
A relatively large current of about 1.5 A is consumed, and a relatively small current of about 100 mA is consumed in the battery unit 5 during the reception period Rx.

The current consumed during the transmission period Tx is 5
The fluctuation in the range of about 00 mA to 1.5 A is because the power consumption of the transmission circuit unit 4 greatly changes depending on the wireless environment in which the digital mobile phone 1 is placed. Due to such characteristics of the current consumption of the battery unit 5 in the reception period Rx and the transmission period Tx, as shown in the time chart of FIG. 2A, a stable battery voltage with little variation is received in the reception period Rx. As shown in the figure, in the transmission period Tx, the battery voltage is much lower than in the reception period Rx, and the degree of the voltage drop varies.

On the other hand, in the standby mode, as shown in FIG.
As shown in (B), the battery unit 5 intermittently stably consumes a current of about 100 mA only during the reception period Rx, and the battery voltage for each reception period Rx is stable. (Description of Method for Microcomputer 8 to Determine Battery Remaining Amount Level) Next, the operation for displaying the battery remaining amount level performed under the control of the microcomputer 8 will be described.

The microcomputer 8 samples the voltage signal constantly sent from the A / D converter 7, and this sampling is performed at the timing of each reception period Rx in both the communication mode and the standby mode. To do. This is because in both the communication mode and the standby mode, the battery voltage during the reception period Rx is stable, so that voltage data suitable for determining the remaining battery level can be sampled. And the microcomputer 8
Shows the sampled voltage of the battery unit 5 in the ROM 3
The four threshold value table numbers stored in 0. The battery level of the battery unit 5 is determined by comparing with one threshold table selected from 1 to 4.

Four threshold value table Nos. 1 to 4 are set as follows. FIG. 3 is a discharge characteristic diagram of the battery unit 5 using the dedicated battery 20, and shows the relationship between the time of continuous communication and the battery voltage. In FIG. 3, a hatched band region 100 is a discharge characteristic when the dedicated battery 20 is new and the resistance of the battery unit 5 is small, and a curve 101 on the upper end side of the band region 100 indicates an idle period and a reception period. (When the current consumption is about 100 mA)
The curve 102 on the lower end side of the band area 100 corresponds to the maximum current consumption during the transmission period (when the current consumption is about 1500 mA).

Threshold table No. corresponding to the new dedicated battery 20. 1 is set as follows based on this discharge characteristic diagram. Here, in accordance with the display form on the remaining amount level display section 40 described above, in the range from the state of the battery capacity Full until the curve 102 reaches the limit voltage P0, there are four levels of remaining amount level, that is, the remaining amount. The level L4, the remaining amount level L3, the remaining amount level L2, and the remaining amount level L1 are sequentially determined, and the threshold value is set so that the remaining amount level E is determined after the curve 102 reaches the limit voltage P0. Shall be performed.

In this case, as shown in FIG. 3, each remaining level L4,
It is understood that the voltage indicated by the curve 102 may be set as the threshold values S1, S2, S3, S4 at the times t1, t2, t3, t4 corresponding to the boundaries between L3, L2, L1 and the remaining amount level E. Here, time point t4 is a time point when the curve 102 reaches the limit voltage P0. Also, the threshold table N
o. 2 and 3 are set as follows.

The internal resistance increases as the dedicated battery 20 is repeatedly charged and discharged, and the dedicated battery 20 and the terminals 5a, 5 are connected.
Due to the increase in contact resistance with b, the battery unit 5
Considering the case where the resistance of No. 1 increases, the ratio of the voltage drop accompanying the load current increases, so that the discharge characteristic is
A change occurs compared to 00. In this case, the band region of the discharge characteristic of the battery unit 5 in which the resistance is increased has the curve 10
Although it is almost the same as 1, the lower end side is lower in the voltage lowering direction than the curve 102.

In the curve 112 shown by the broken line in FIG. 3, the voltage drop amount at the time of transmission (at the maximum current) with respect to the time of reception is increased by ΔV as the resistance of the battery unit 5 is increased, and the lower end side is correspondingly increased. It shows a state of being shifted downward from the curve 102. In the curve 112 of FIG. 3, the limit voltage P0 is reached long before the time point t4 (near the time point t3). In such a case, if the threshold level S1, S2, S3, S4 set based on the curve 102 is used as it is to determine the remaining battery level, the display of the remaining battery level indicates that there is still a remaining battery level. However, the minimum battery voltage at the time of transmission has reached the limit voltage P0, which means that the appropriate remaining amount level is not displayed.

On the other hand, the threshold value S1 + ΔV, S2 + added to the threshold values S1, S2, S3, S4 by the voltage drop amount ΔV.
If the remaining amount level is determined using ΔV, S3 + ΔV, S4 + ΔV, the influence of the deviation of the voltage drop amount ΔV on the curve 112 is corrected and an appropriate remaining amount can be displayed. That is, with this correction, the minimum battery voltage at the time of transmission reaches the limit voltage P0 at the time t4 when the remaining amount level changes from L1 to E.

The thresholds S1 + ΔV, S2 + ΔV, S
3 + ΔV, S4 + ΔV is the curve 112 obtained by moving the curve 101 upward by ΔV in FIG. 3 at time points t1, t2, t.
This corresponds to the voltage value indicated at 3 and t4. As described above, in the present embodiment, as the threshold table of the dedicated battery 20, the threshold table No. 1 (assuming the resistance value of the battery unit 5 is about 150 mΩ),
Two threshold table numbers used when the resistance increases.
2, threshold table No. 3 was set.

Threshold table No. 2 is when the resistance of the battery unit 5 increases by about 100 mΩ (resistance value 250 mΩ
Voltage drop ΔV from the difference between the maximum current during transmission and the current during reception (1500-100 = 1400 mA)
1 is calculated, and the value ΔV1 (140 mV) is set to the threshold table No. It is added to 1. In addition, the threshold table No. 3 assumes a case where the resistance of the battery unit 5 has increased by about 200 mΩ (resistance value of about 350 mΩ), and similarly calculates the voltage drop ΔV2 (280 mV) in the threshold table N.
o. It is added to 1.

Table 1 shows the threshold table N for the dedicated battery 20.
o. An example of 1-3 is shown.

[0039]

[Table 1]

Threshold table No. for battery pack Four
Is set as follows. The internal resistance of the alkaline dry battery of the battery pack is considerably larger than that of the dedicated battery 20 (about 500 mΩ). The nominal voltage (4.5V) of the battery pack is different from the nominal voltage (3.6V) of the dedicated battery 20. However, the threshold table No.
4, the basic setting method is the same, and based on the discharge characteristic diagram (not shown) when the battery pack containing the alkaline battery is used for the battery unit 5, the same setting as the case of the dedicated battery 20 is performed. Is set by the way.

Table 2 shows threshold table numbers for alkaline dry battery battery packs. 4 is an example.

[0042]

[Table 2]

Next, the microcomputer 8 sets the four threshold value table numbers. A procedure of selecting one appropriate threshold value table from 1 to 4 according to the resistance value of the battery unit 5 will be described. In the present embodiment, the difference (N1−N2) between the voltage N1 of the battery unit 5 when no load is applied and the voltage N2 of the battery unit 5 when a predetermined load current (for example, 200 mA) is applied is calculated, and this (N1 An appropriate threshold table is selected based on N2).

Since the value of (N1-N2) is almost proportional to the resistance of the battery section 5, based on the value of (N1-N2),
It is possible to determine how much resistance the battery unit 5 has, and also to determine whether the battery unit 5 uses the dedicated battery 20 or the alkaline dry battery pack. As a method for measuring the voltage N1 and the voltage N2, generally, the voltage N2 is measured when a substantially constant load current flows through the battery unit 5, and the voltage N1 is measured without a load, but when measuring the voltage N1. Alternatively, it may be measured with some load.

In this embodiment, the voltage N1 is measured in the no-load state immediately after the power switch 9 is turned on, and when the LED 11 is turned on, the battery unit 5 is also connected to 200 m.
By utilizing the fact that a load current of about A flows, the LED 11
Although the voltage N2 is measured at the time of lighting, it is also possible to separately provide a dummy load resistor and measure the voltage N2 in the state where a predetermined current is passed through the dummy load resistor.

Here, it is assumed that the values of the voltages N1 and N2 are read in units of 20 mV, so that the value of (N1-N2) is also read in units of 20 mV, and the value of the predetermined load current at the time of measuring the voltage N2 is 200 mA. explain. In this case, the resistance value (Ω) of the battery unit 5 can be considered to be close to the value represented by (N1−N2) ÷ 200. Therefore, (N1
It is possible to determine the resistance value of the battery section 5 based on the value of −N2) and select an appropriate threshold table. Table 3
Is an example of a specific threshold table determination criterion.

[0047]

[Table 3]

According to Table 3, (N1-N2) is 40 m
When it is less than V, the resistance of the battery unit 5 is regarded as about 150 mΩ and the threshold value table No. Select 1. (N1
-N2) is 60 mV, the resistance of the battery unit 5 is 2
The threshold value table No. is regarded as about 50 mΩ. Select 2. When (N1-N2) is 80 mV, the battery unit 5
Of the threshold value table N
o. Select 3.

When (N1-N2) is 100 mV or more,
Assuming that a battery pack (about 50 mΩ) is used for the battery unit 5, the threshold value table No. Select 4. As described above, (N1-N2) can be used as a parameter for determining the resistance of the battery unit 5, and an appropriate threshold table can be selected based on this.

FIG. 4 is a flow chart showing the operation of the microcomputer 8 for determining and displaying the remaining battery level. As soon as the power switch 9 is turned on, the voltage data from the A / D converter 7 is sampled to measure the voltage N1 of the battery unit 5 in the unloaded state (S1).

Next, the LED 11 is turned on (S2).
At this time, a current of about 200 mA flows through the LED 11, and a similar load current also flows through the battery unit 5. In this state, the voltage data from the A / D converter 7 is sampled to measure the voltage N2 of the battery section 5 (S3). The LED 11 is turned on after being turned on for about 10 seconds. Since various operation keys are illuminated by the LED 11 for about 10 seconds, the key operation can be performed easily.

From the voltage N1 measured in step S1 and the voltage N2 measured in step S3, the parameter (N1-N
2) is calculated (S4). This parameter (N1-N2)
(S5) according to the selection criteria of Table 3 above, the threshold table No. Select one from 1-4 (S6
~ S9). Then, until the power switch 9 is turned off, determination of the remaining amount level and display of the determined remaining amount level are repeated using the selected threshold value table (S1).
0, S11).

(Explanation of Effects and Other Matters) As described above, in the digital mobile phone 1, the power switch 9 is used.
A threshold table suitable for the resistance value of the battery unit 5 is selected each time the battery is turned on, and the remaining battery level is determined using the selected threshold table. As a result, even when the internal resistance or contact resistance of the dedicated battery 20 increases, or when a battery pack containing an alkaline dry battery is used, an accurate and accurate remaining battery level corresponding to the resistance value of the battery unit 5 is displayed. can do.

In the present embodiment, four thresholds are set in one threshold table and the remaining level is displayed in five steps from L4 to E. However, the number of thresholds in one threshold table is Any number can be implemented as well. For example, the present invention can be applied to a case where only one threshold value is set in the threshold value table and the remaining amount level display is switched when the remaining battery amount is low.

Further, in the present embodiment, the form in which the dedicated battery 20 or the battery pack of the alkaline dry battery can be used for the battery unit 5 is shown. However, in this digital mobile phone 1, like nickel-cadmium. It is also possible to use a battery pack having a nominal voltage of 3.6 V in which three alkaline secondary batteries are inserted. In this case, since the nominal voltage is 3.6 V and the internal resistance is low, the threshold table No. From 1-3
A threshold table adapted to the resistance of the battery unit 5 is selected, and an appropriate remaining amount level is displayed.

Further, in the present embodiment, an example of the battery level indicator used in the TDMA type mobile phone has been shown, but the present invention is generally a battery used in a portable communication device for transmitting and receiving in a time division manner. It can be applied to the remaining amount indicator.

[0057]

According to the present invention, in a battery level indicator in a portable communication device that transmits and receives in a time division manner, the battery level is determined using a table adapted to the internal resistance of the battery. Even when the internal resistance of the dedicated battery changes or a battery different from the dedicated battery is used, it is possible to display the accurate remaining battery level adapted to the internal resistance of the battery.

According to the third aspect of the invention, the parameter can be measured by utilizing the no-load state and the lighting state of the LED of the portable communication device immediately after the power is turned on,
It is not necessary to separately provide a circuit for parameter measurement.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a digital mobile phone according to an embodiment of the present invention.

FIG. 2 is a time chart showing battery voltage waveforms in a communication mode and a standby mode.

FIG. 3 is a discharge characteristic diagram of a battery unit 5 using a dedicated battery 20.

FIG. 4 is a flowchart showing an operation for determining and displaying a remaining battery level by the microcomputer 8.

[Explanation of symbols]

 1 Digital Mobile Phone 3 Reception Circuit Section 4 Transmission Circuit Section 5 Battery Section 5a Positive Terminal 5b Negative Terminal 6 Voltage Regulator 7 A / D Converter 8 Microcomputer 9 Power Switch 10 LCD 11 LED 20 Dedicated Battery 30 ROM 40 Remaining Level Display Section

Claims (4)

[Claims] 1. A battery level indicator in a portable communication device for transmitting and receiving in a time-division manner, comprising: a detection unit for detecting a battery voltage; a battery voltage detected at a first load; and a battery voltage detected at a second load. Corresponding to possible battery voltage values, with a measuring means for measuring a parameter corresponding to the battery internal resistance based on the detected battery voltage and a plurality of tables provided in advance according to possible values of the parameter. Table means for indicating the remaining battery level, selecting means for selecting a table corresponding to the measured parameter, and determining means for determining the remaining battery level corresponding to the battery voltage detected by the detecting means according to the selected table And a display unit for displaying the determined remaining battery amount on the display unit. 2. The battery level according to claim 1, wherein the measuring means measures a difference between a battery voltage under the first load and a battery voltage under a second load as the parameter. display. 3. The first load is in a state immediately after powering on the portable communication device, and the second load is lighting of a backlight LED for causing a display unit of the portable communication device to emit light. The battery level indicator according to claim 2, which is in a state. 4. The display means displays the remaining battery level in multiple stages, and the table means determines, for each parameter of a predetermined width, which of the multiple stages of remaining battery level corresponding to the battery voltage value. The battery level indicator according to any one of claims 1 to 3, further comprising a plurality of tables that hold thresholds for the battery.