United States Patent
`Tamura
`
`1191
`
`[11] Patent Number:
`
`5,043,651
`
`[45] Date of Patent:
`
`Aug. 27, 1991
`
`[54] APPARATUS FOR DISPLAYING THE
`REMAINING CHARGE OF
`
`Attorney. Agent. or F1'rm—Sughrue, 1Vlion. Zinn
`Macpeak & Seas
`
`RI-ZCHARKGEABLE BATTERY
`Yoshiharu Tamura, Tokyo, Japan
`Inventor:
`
`[75]
`
`[73] Assignee: NEC Corporation, Tokyo. Japan
`
`[21] Appl. No.: 406,473
`
`[22] Filed:
`
`Sep. 13. 1989
`
`Foreign Application Priority Data
`[30]
`Sep. 13. 1933 [JP]
`Japan .............................. .. 63.227384
`
`Int. Cl.5 ...................... .. I-I02J 7/04; HOIM 10/44
`[51]
`
`[52] U.S. C1.
`.
`.............. .. 320/43; 320/44;
`320/48
`[58] Field of Search ..................... ., 320/13, 14, 37, 38.
`320/43, 44, 48
`
`[56]
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`6/1987 Kopmann ............................ .. 320/44
`4.677.363
`4,775,827 10/1988
`ljntema et al.
`...................... .. 320/44
`4.835.453
`5/1989 Munning Schmidt et al.
`320/13
`320/13
`4,849,681
`7/1989 Munning Schmidt et al.
`
`[57]
`
`ABSTRACT
`
`An apparatus having a rechargeable battery and a bat-
`tery voltage detector which detects the output voltage
`of the battery to produce a detection signal when the
`output voltage falls below a predetermined threshold
`level. A controller stores a battery capacity value and
`accumulates the discharge of the battery to produce an
`accumulated capacity value. The controller also calcu~
`lates a difference between the stored capacity value and
`the accumulated capacity value. Using the difference. a
`display displays the remaining charge value of the bat-
`tery thereon. If the difference exceeds a predetermined
`value at a time the controller receives the detection
`signal, the controller changes the stored capacity value
`to a new capacity value. Alternatively. the controller
`may change a rate of accumulating the battery dis-
`charge.
`The apparatus may have a current detector for detect-
`'ing a current flowing through the battery. The control-
`ler may accumulate the battery discharge based on the
`detected Current.
`'
`
`Primary Exam1'ner———Hicltey: R. J.
`
`28 Claims. 5 Drawing Sheets
`
`_______________ _ _ .1
`
`
`
`.
`1 40
`1
`i
`g
`I
`1 4.
`1
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`
`4
`
`1
`
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`43A-"l
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`.
`
`E
`E
`1
`AID 1:011
`CURRENT
`1
`1
`DETECTOR
`1
`1
`
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`'."
`L. _ ___ _ _. _ __i
`"""""""""""""""""""""""""" _ ;A_3Kfi£Ev— - T T "
`
`16
`
`DISPLAY
`
`
`
`1
`
`I
`
`1
`1.
`'.
`J
`
`1
`
`VREF
`
`_
`
`PACKAGE
`
`EXH1BlT
`Petitioner . Kyocera
`
`PX 1029
`
`Kyocera PX 1029_1
`
`

`
`U.S. Patent
`
`Aug. 27, 1991
`
`Sheet 1 of 5
`
`5,043,651
`
`RECHARGEABLE
`4 emgny pgcmg
`
`_
`
`1
`
`1 ELECTRICAL EQUIPMENT
`
`
`
`
`DISPLAY
`I I III
`
`
`Kyocera PX 1029_2
`
`Kyocera PX 1029_2
`
`

`
`U.S. Patent
`
`Aug. 27, 1991
`
`Sheet 2 of 5
`
`5,043,651
`
`FIG. 3
`
`
`
`MEASURE ti
`AT Ii
`
`CALCULATE
`A =ZiI0; ' Ii ‘ti
`
`CALCULATE
`CR =Cf‘A
`
`DISPLAY CR
`
`
`
`YES
`
`A
`
`MEASURE in
`AT In
`
`CALCULATE
`A1'=ZiI0j ‘I; -ti
`
`CALCULATE
`CRT = Cf - A1’
`
`36
`
`S7
`
`38
`
`39
`
`® “°
`
`
`CALCULATE
`Cf’ = Cf ' (CRT ‘CWT
`CHANGE Cf “Cf
`
`RESET A
`TO BE 0
`
`.
`
`'
`
`$11
`
`Kyocera PX 1029_3
`
`Kyocera PX 1029_3
`
`

`
`U.S. Patent
`
`Aug. 27, 1991
`
`Sheet 3 of 5
`
`5,043,651
`
`Kyocera PX 1029_4
`
`Kyocera PX 1029_4
`
`

`
`U.S. Patent
`
`Aug. 27, 1991
`
`Sheet 4 of 5
`
`5,043,651
`
`DISPLAY
`
`
`
`
`
`-
`'
`
`I.
`
`I”““““““““““““““““““““ “‘ 7
`1
`16
`1I
`{
`1
`:
`I
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`*I
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`43A/1,
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`g
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`L- __}
`i
`
`
`
`L_____:___J
`
`I
`I
`#
`: 41
`[
`
`L. ___________________________________ __ _J
`M BATTERY
`PACKAGE
`
`FIG. 7
`
`Kyocera PX 1029_5
`
`Kyocera PX 1029_5
`
`

`
`U.S. Patent
`
`Aug. 27, 1991
`
`Sheet 5 of 5
`
`5,043,651
`
`FIG. 8A I
`
`“G 33
`
`S3
`
` S11
`
`
`oerecr I;
`
`
`
`
`
`
`DIVISION
`CIRCUIT
`
`
`
`MEMORY
`Iflpmm
`
`
`
`Kyocera PX 1029_6
`
`Kyocera PX 1029_6
`
`

`
`1
`
`5,043,651
`
`APPARATUS FOR DISPLAYING THE
`REMAINING CHARGE OF RECHARGEABLE
`BATTERY
`
`BACKGROUND OF THE INVENTION
`
`invention relates to an apparatus for
`The present
`displaying a remaining charge of a rechargeable battery
`and, more particularly, to an apparatus for displaying
`the remaining battery charge based on an accumulated
`discharge value which is computed from operating
`current and time of battery usage.
`In a conventional apparatus, a storage section stores a
`fixed battery capacity value which is usually a standard
`full charge capacity of a rechargeable battery A con-
`troller computes an accumulated discharge value based
`on the operating current and time of usage by electrical
`equipment to which power is supplied from the re-
`chargeable battery. By comparing the stored battery
`capacity value with the accumulated discharge value,
`the remaining charge value of the battery can be ob-
`tained and displayed.
`The conventional apparatus mentioned above has the
`following problems. Rechargeable batteries, such as a
`Ni-Cd alkaline battery, gradually decrease their full
`capacities as the number of recharging operations in-
`creases. Thus, the displayed charge value which is cal-
`culated using the stored, fixed battery capacity will
`differ from the actual remaining battery charge value.
`As a result, even though the displayed remaining charge
`value shows that the electrical equipment can still be
`operated by the battery, the equipment would suddenly
`stop for lack of battery energy.
`Since different batteries have different capacities due
`to manufacturing variations, the standard capacity of
`batteries must be set to the minimum capacity among all
`batteries. This results in more charging operations,
`shortening the lives of batteries except for a battery
`having the minimum capacity.
`Furthermore, the electrical equipment might use bat-
`teries having different capacities because of its limita-
`tion in size or in weight. In this case,
`the displayed
`remaining battery charge value which is calculated
`using the fixed battery capacity will also differ from the
`actual remaining battery charge value.
`SUMMARY OF THE INVENTION
`
`An object of the present invention is, therefore, to
`- provide a generally improved apparatus which displays
`the remaining battery charge value and eliminates the
`above-mentioned problems.
`Another object of the present invention is to provide
`a battery remaining charge display apparatus capable of
`making the displayed remaining battery charge substan-
`tially consistent with the actual
`remaining battery
`charge.
`Yet another object of the present invention is to pro-
`vide an apparatus having a so-called self-learning func-
`tion which changes a stored variable, such as a battery
`capacity, based on actual battery conditions.
`According to the present invention, there is provided
`an apparatus having a rechargeable battery and a bat-
`tery voltage detector which detects the output voltage
`of the battery to produce a detection signal when the
`output voltage falls below a predetermined threshold
`level. A controller stores a battery capacity value and
`accumulates the discharge of the battery to produce an
`accumulated capacity value. The controller also calcu-
`
`_
`
`10
`
`15
`
`20
`
`25'
`
`30
`
`35
`
`40
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`45
`
`50
`
`55
`
`60
`
`65
`
`2
`lates a difference between the stored capacity value and
`the accumulated capacity value. Using the difference, a
`display displays the remaining charge value of the bat-
`tery. If the difference exceeds a predetermined value at
`a time the controller receives the direction signal, the
`controller changes the stored capacity value to a new
`capacity value. Alternatively,
`the controller may
`change the rate of accumulating the battery discharge.
`The apparatus may have a current detector for de-
`tecting a current flowing through the battery. The con-
`troller may accumulate the battery discharge based on
`the detected current.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`The above and other objects, features and advantages
`of the present invention will become more apparent
`from the following description referring to the accom-
`panying drawings, in which:
`FIG. 1 is a schematic diagram showing an apparatus
`according to an embodiment of the present invention;
`FIGS. 2A, 2B and 2C are graphs for explaining the
`operation of the FIG. 1 apparatus;
`FIG. 3 is a flow chart showing the operation of the
`FIG. 2 apparatus;
`FIG. 4 is a perspective view of a hand-held mobile
`telephone embodying the present invention;
`FIGS. 5A to SF are flow charts showing modifica-
`tions to the FIG. 1 apparatus;
`FIG. 6 is a schematic block diagram showing an
`apparatus according to another embodiment ofthe pres-
`ent invention;
`‘
`FIG. 7 is a side view ofa hand-held mobile telephone
`incorporating the FIG. 6 apparatus therein;
`FIGS. 8A and 8B are flow charts showing the opera-
`tion of the FIG. 6 apparatus; and
`FIG. 9 is a block diagram showing the controller
`used in the FIG. 1 or FIG. 6 apparatus.
`DETAILED DESCRIPTION OF THE
`PREFERRED EMBODIMENTS
`
`In FIG. 1, a battery package 4 is attached through
`terminals 44 and 45 to electrical equipment 1 which is
`powered by a rechargeable, or secondary. battery 43 in
`the package 4. The battery 43 is recharged by a battery
`charger (not shown) to be connected to terminals 40
`and 41. The battery 43 may comprise a Ni-Cd alkaline
`' battery. A diode 42 is inserted to prevent current from
`flowing from the battery 43 to the battery charger and
`to prevent short circuit damage to the battery 43.
`The equipment 1 includes a battery voltage detector
`14, a controller, or central processing unit (CPU) 15, a
`display 16 and other circuitry (not shown), such as
`circuitry used for a portable telephone. The controller
`15 may be composed of a microprocessor. The detector
`14 includes a voltage comparator 141 receiving the
`output voltage V3 of the battery 43 and a threshold
`voltage Vrythrough the terminal 44 and a terminal 142,
`respectively. Iftlie voltage V3 falls below the threshold
`voltage V7-H, the detector 14 outputs a detection signal
`and provides it to the controller 15.
`The controller 15 computes an accumulated dis-
`charge value (A) of the battery 43 in accordance with
`the following equation:
`
`
`
`1-1:20,‘-/,'-I,-I
`
`(1)
`
`Kyocera PX 1029_7
`
`Kyocera PX 1029_7
`
`

`
`5,043,651
`
`4
`
`3
`where a,~ is a weighting constant, I,- is an operating cur-
`rent of the equipment 1 and t,- is a time for which the
`equipment 1 operates at the current L: The discharge
`value changes depending on a value of a discharge
`current, because of the internal resistance of the battery
`43. The weighting constant a; is employed to compen-
`sate for this discharge change. In general, if I] is greater
`than 12, a1 is also greater than a2. It can be understood
`from the above equation (1) that an accumulating rate of
`the battery discharge can be changed by changing the
`weighting constant a,-_
`The controller 15 stores therein the weighting con-
`stant a,~, the operating current I,- and a battery capacity
`CfWl’1lCl'1 are changeable based on the conditions of the
`battery 43 as described later. Also the controller 15
`measures the operating time t; at the current 1,: After
`computing the accumulated discharge value A,
`the
`controller 15 calculates a subtraction value CR between
`the values Cfand A as follows:
`
`CR=Cf—.-1
`
`Using the value CR, the controller 15 causes the display
`16 to display the remaining battery charge value
`thereon. In the instant example, the display 16 has a bar
`graph 161.
`The controller 15 changes the stored battery capacity
`C_fOI' weighting constant a; in response to the detection
`signal from the battery voltage detector 14. This opera-
`tion will now be described in detail with reference to
`FIGS. 2A to 2C. It is desirable that the displayed re-
`maining charge value becomes zero shortly before the
`actual remaining charge becomes zero and to thereby
`have the user charge the battery 43 before the equip-
`ment 1 stops its operation due to the lack of power. This
`difference between the displayed and actual remaining
`charge values will hereinafter be referred to as a margin
`value Cm,
`In this instance, the following is set:
`
`Cf-A7'=CR7ԤO
`
`where Arand Cgrare the accumulated discharge value
`and the subtraction value, respectively, at a time the
`battery voltage V5 falls below the threshold level V771.
`In other words, the margin value Cm is selected to be
`equal to or less than zero (Cm-E0).
`In FIG. 2A, the margin value Cm is set to be -5, the
`‘battery capacity Cf is 100 and the accumulated dis-
`charge value Ar is 110. Thus,
`the subtraction value
`Cgris given as follows:
`
`CR7'=Cf—-AT=lO0——ll0=—lO.
`
`Since this subtraction value CRr(--10) is less than the
`margin value Cm (— 5), the controller 15 adds no change
`to the battery capacity Cf. For the next calculation, the
`same battery capacity Cfwill be used.
`In FIG. 2B, the accumulated discharge value A7 is
`calculated to be 102, which would be caused by the
`aging of the battery or other reasons. In this case, the
`subtraction value Cgris shown below.
`
`CR7‘: lOO— I02: -2.
`
`Since the subtraction value CR7-(-2) is greater than the
`margin value C,,, (—5), the ‘controller 15 changes the
`
`5
`
`10
`
`15
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`20
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`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`battery capacity C/‘to a new battery capacity Cf which
`is calculated by an equation:
`
`Cf=Cf-(CR7'—-Cm)= lOO—(—3—(-5))=97.
`
`For the next calculation, the new battery capacity Cf
`will be used.
`
`In FIG. 2C, a battery having a smaller battery capac-
`ity is used for the same equipment 1 in which the battery
`capacity Cf is stored. In this case, if the controller 15
`calculates an accumulated discharge value based on the
`stored battery capacity C/=100, the actual remaining
`charge value becomes zero before the displayed value
`becomes zero and thereby the equipment 1 cannot work
`properly, even though the displayed remaining charge
`value still
`indicates that
`the battery charge remains
`enough to operate the equipment 1. According to the
`present invention, on the other hand, the stored battery
`capacity Cfwill be changed‘ based on the accumulated
`discharge value Ar. Since the value Aris 95, the sub-
`traction value CR7-is computed below.
`
`CRr=Cf—Ar=lOO—95=5.
`
`This value CRr(5) is greater than the margin value Cm
`(-5). Thus, the battery capacity Cf is changed to 90
`using the equation C/==Cf—-(CR7—C,,,). For the next
`use,
`the displayed remaining charge value properly
`suggests that
`the user charge the battery before the
`equipment 1 stops its operation.
`Referring to FIG. 3, the operation of the controller
`15 will be discussed in further detail. At step S1. the
`controller 15 measures an operating time t,-at an operat-
`ing current
`I,-. Then,
`the controller 15 calculates an
`accumulated discharge value in accordance with the
`equation (1) mentioned earlier. Next,
`the subtraction
`value C12 is computed using a stored battery capacity Cf
`and the accumulated discharge value A, at step S3. The
`computed value CR is displayed on the display 16 at step
`S4.
`
`If the battery voltage V3 is above the threshold level
`V7-H, however, the operation moves to step S6 at which
`an operating time t,‘TaI an operating current I,'ris mea-
`sured. At step S7, the controller 15 calculates the accu-
`mulated discharge value Arat a time it receives a detec-
`tion signal from the voltage detector 14. Using the
`stored battery capacity Cfand calculated value Ar, the
`subtraction value CRT therebetween is calculated at
`Step S8.
`.
`Ifthe value Cgris greater than the margin value Cm,
`the operation goes to step S10 atwhich a new battery
`capacity
`Cf,
`is
`calculated
`by
`the
`equation
`Cf-(CRr— Cm) and the capacity Cfis changed to Cf’.
`Then, the accumulated charge value A is reset to zero at
`step S11. Ifthe subtraction value Cgris smaller than the
`margin value Cm at step S9, this step is followed by step
`S11.
`
`the present invention is embodied in a
`In FIG. 4,
`hand-held radio telephone 5. The battery package 4 is
`attached to the telephone 5. A display 16A displays the
`battery remaining charge thereon using characters like
`-“BATT 30%” instead of the bar graph. The telephone
`5 has a keyboard 6 which may be connected to the
`controller 15, as indicated by a broken line in FIG. 1.
`The telephone 5 also includes an external I/O connec-
`tor 7 (see FIG. 1) which may be connected to the con-
`'troller 15 and which receives a remotely transmitted
`control signal. Such equipment having a keyboard and
`
`Kyocera PX 1029_8
`
`Kyocera PX 1029_8
`
`

`
`5
`an external 1/O connector may have the following addi-
`tional functions.
`
`5,043,651
`
`(1) The battery capacity Cfcan manually be rewritten
`by a signal inputted through the keyboard 6 or can be
`remotely rewritten by the control signal. See FIG. SA.
`(2) The battery capacity Cf or Cf can manually be
`reset to be a prescribed value Cfg through the keyboard
`6 or can be remotely reset by the control signal. See
`FIG. 5B.
`(3) When the subtraction value CRrexceeds the mar-
`gin value, C,,., the weighting constant a,- can be changed
`to a new weighting constant a; instead of changing the
`battery capacity Cf. See step S15 in FIG. 5C.
`(4) In case of (3), the constant a,~ is calculated by the
`following equation:
`
`I
`C_/'+ C". = E.a,*-I,'>t,‘.
`
`See FIG. 5C.
`
`(5) In case of (3), the weighting constant a; can manu-
`ally be written through the keyboard 6 or can remotely
`be rewritten by the control signal. See FIG. SD.
`(6) In case of (3), the weighting constant a; or a,-' can
`manually be reset to a prescribed value a,-,, through the
`keyboard 6 or can remotely be reset by the control
`signal. See FIG. SE.
`(7) The user can manually clear the accumulated
`charge value A to be 0 at a time when he starts to use
`the equipment 1 with a fully charged battery 43. In this
`case, step S11 need not be included in the flow chart of
`FIG. 3. See FIG. 5F.
`
`When two batteries having different capacities are
`used or a brand-new battery and a used battery are
`alternatively used,
`the battery capacity Cf or
`the
`weighting constant a,-can properly be set to aprescribed
`value using the function (1) or (5) above. In addition,
`when a battery which is not fully charged is used, the
`battery capacity Cfor the weighting constant a; can be
`reset to a prescribed value Cfg or a,-,, using the function
`(2) or (6). Otherwise,
`the value Cf or a,- would be
`changed to a smaller value which does not properly
`reflect the actual battery capacity.
`It is important to decide a start time of operation of
`the apparatus with a fully charged battery. The simplest
`and most reliable way may be to manually clear the
`- accumulated discharge value A to be zero in such a way
`as in case of (7). Alternatively, a first turning-on of a
`power switch of the equipment 1 receives a charge
`completion signal automatically sent from a battery
`charger which is to be connected to the equipment
`through the battery 43.
`In FIG. 6, the same numerals as those in FIG. 1 indi-
`-~ cate the same elements as those in FIG. 1. A battery
`package 4A accommodates not only a battery 43A and
`a diode 42 but also a battery voltage detector 14, a
`controller 15A and a display 16 which in the FIG. 1
`embodiment are included in the electrical equipment 1.
`In addition to the functions of controller 15, the control-
`ler 15A has additional functions described below. The
`battery package 4A has terminals 44 and 45 through
`which the battery 43A is electrically connected to elec-
`trical equipment. The package 4A further includes_a
`current detector 18 having a current sensor resistor 181
`contained in the battery 43A, an analog-to-digital
`(A/D) converter 182 and a voltage stabilizer 183.
`
`5
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`6
`flowing there-
`The resistor 181 senses a current
`through. The stabilizer 183 is connected to the battery
`43A and supplies a stabilized reference voltage V R EFIO
`A/D converter 182. Using the reference voltage VREF,
`A/D converter 182 converts the sensed analog current
`into a digital value and provides the digital value to the
`controller 15A as a detected current I,~(see FIG. 8A). It
`is to be noted that the current detector 18 can detect not
`only a discharge current but also a charge current.
`Using the detected current I,, the controller 15A calcu-
`lates an accumulated discharge or charge value A and
`then computes a subtraction value CR=Cf—A. This
`value CR correctly reflects the actual remaining battery
`charge, even if the charging operation has taken place
`before the completion of discharge. In this case, how-
`ever, the accumulated discharge value may be negative,
`i.e., the value CR may exceed the battery capacity Cf. If
`so, the controller 15A sets the value CR to the value Cf
`and displays it on the display 16 (see FIG. 8B).
`In FIG. 7, the battery package 4A has the display 16B
`on a side wall thereof. The display 16B is composed of
`a plurality of light emitting diodes (LEl5s). In the Fig-
`ure, four LEDS are lit to indicate that 80% of charge
`remains in the battery.
`In FIG. 9, the controller 15 or 15A includes a counter
`circuit 151, a self discharge compensation (SDC) circuit
`152, a memory 153, a division circuit 154. a clock gener-
`ator 155 and a crystal oscillator element 156. The SDC
`circuit 152 produces an SDC signal indicating a value of
`self discharge of the battery 43 or 43A. The memory
`153 stores and rewrites the battery capacitor Cfor the
`weighting constant a;. The memory 153 may be an elec-
`trically erasable programmable read-only memory (E3‘
`PROM).
`The clock generator 155 generates clock pulses in
`cooperation with the element 156 and provides them to
`various circuits of controller 15 or 15A. The counter
`circuit 151 counts up an accumulated charge value A
`based on a fixed or detected current I,- and subtracts the
`value A from the value Cfstored in memory 153. The
`resultant CR is supplied to the division circuit 154 which
`divides the value CR by the value Cf. The divided value
`CR/Cf is supplied to the display 16 to be displayed
`thereon. When receiving a detection signal from the
`voltage detector 14, the counter circuit 151 produces a
`value CRr—C,,, from the value Cf to produce a new
`capacity Cf. The counter circuit 153 may be comprised
`of several counters and gates.
`What is claimed is:
`1. An apparatus for monitoring_ the residual capacity
`of a battery comprising:
`means for detecting the output voltage of a battery
`and for producing a detection signal when said
`output voltage falls below a predetermined thresh-
`old level;
`means for storing a first value;
`means for accumulating the discharge of said battery
`to produce a second value;
`first means for calculating a difference between said
`first and second values to produce a difference
`value;
`means responsive to said difference value for display-
`ing the remaining charge value of Siild battery;
`second means responsive to said detection signal for
`providing said second value to said calculating
`means; and
`means for changing either said first value or an accu-
`mulating rate of said accumulating means when
`
`Kyocera PX 1029_9
`
`Kyocera PX 1029_9
`
`

`
`5,043,651
`
`7
`said difference value is higher than a predeter-
`mined value.
`
`2. An apparatus as claimed in claim 1, wherein said
`storing means comprises means for storing a battery
`capacity Cf of said battery as said first value, and 5
`wherein said accumulating means comprises
`third
`means for calculating said second value (A) according
`to an equation;
`
`A =Z_fl,"I,'-!,',
`I
`
`10
`
`15
`
`20
`
`25
`
`30
`
`where: a; is a weighting value, I,- is an operating cur-
`rent and t,- is an operating time at said current 1,’, and
`wherein said first means comprises means for sub-
`tracting said second value A from said first value
`C] to produce said difference value CR=Cf—A.
`3. An apparatus as claimed in claim 2, further com-
`prising:
`current detector means for detecting a current flow-
`ing through said battery to produce a detected
`current value; and
`fourth means for providing said detected current
`value to said third means as said operating current
`1,‘.
`4. An apparatus as claimed in claim 3, wherein said
`current detector means comprises:
`a resistor connected in series with said battery;
`means receiving a voltage from said battery for pro-
`ducing a stabilized reference voltage; and
`means connected to said resistor and responsive to
`said reference voltage for detecting said current
`flowing through said resistor to produce a detected
`current, for converting said detected current into a
`digital value and for producing said digital value as
`said detected current value.
`5. An apparatus as claimed in claim 3, further com-
`prising package means for accommodating said battery,
`said detecting means, said accumulating means, said
`storing means, said first and second means, said chang-
`ing means, said current detector means and said fourth
`means, said displaying means being attached to said
`package means.
`6. An apparatus for monitoring residual capacity of a
`battery comprising:
`means for storing a first value;
`first means for producing a first detection signal when
`the output voltage ofa battery falls below a prede-
`termined threshold value;
`means for accumulating the discharge of said battery
`to produce an accumulated discharge value;
`means responsive to said first value and said accumu-
`lated value for calculating the remaining charge of
`said battery to produce a remaining charge value;
`means for displaying said remaining charge value;
`means responsive to said first detection signal for
`comparing said remaining charge value with a
`predetermined value to produce a change signal
`when said remaining charge value exceeds said
`predetermined value; and
`means responsive to said change signal for changing
`either said first value or an accumulating rate of (,5
`said accumulating means.
`.
`7. An apparatus as claimed in claim 6, further com-
`prising a rechargeable battery.
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`8
`8. An apparatus as claimed in claim 7, wherein said
`rechargeable battery comprises a Ni-Cd alkaline bat-
`tery.
`9..An apparatus as claimed in claim 6, wherein said
`first means comprises voltage comparator means for
`comparing the output voltage of said battery and said
`predetermined threshold value to produce said first
`detection signal when said output voltage falls below
`said predetermined threshold value.
`10. An apparatus as claimed in claim 6, wherein said
`displaying means comprises a bar-graph type display.
`11. An apparatus'as claimed in claim 6. further com-
`prising means for detecting a current flowing through
`said battery to produce a second detection signal,
`wherein said calculating means comprises means re-
`sponsive to said first value, said accumulated discharge
`value and said second detection signal for calculating
`said remaining charge of said battery to produce said
`remaining charge value.
`12. An apparatus comprising:
`a battery adapted to power electrical equipment;
`a display;
`means for storing a battery capacity value Cfl
`means for detecting the output voltage of said battery
`to produce a detection signal when said output
`voltage falls below a predetermined threshold
`value;
`first means for calculating an accumulated discharge
`value A of said battery by an equation
`
`.-1 = Zn,-~I,'-I,
`1
`
`I,- is an operating
`where a; is a weighting constant,
`current of said equipment and t,-is a time for which
`said equipment operates at said current I,-;
`second means for calculating a difference CR between
`said values Cfand A, CR=Cf—~A;
`means responsive to said difference CR for displaying
`on said display the remaining charge value of said
`battery;
`means responsive to said detection signal for compar-
`ing said difference with a predetermined value C,,,
`to produce a change signal when said difference is
`equal to or greater than said value Cm; and
`means responsive to said. change signal for replacing
`either said value C/‘or said constant a,' with a new
`capacity value Cf or a new weighting constant a,~.
`13. An apparatus as claimed in claim 12, wherein said
`equipment comprises a radio telephone.
`14. An apparatus comprising:
`a battery adapted to provide power to electrical
`equipment;
`voltage detector means for producing a detection
`signal when the output voltage of said battery falls
`below a predetermined threshold value;
`means for storing a first value;
`means for calculating a first remaining charge value
`of said battery based on said first value;
`display means for displaying said first
`charge value;
`means responsive to said detection signal for calculat-
`ing a second remaining charge value of said battery
`based on said first value; and
`means for changing said first value when said second
`remaining charge value exceeds a predetermined
`value.
`
`remaining
`
`Kyocera PX 1029_10
`
`Kyocera PX 1029_10
`
`

`
`9
`15. Ari apparatus as claimed in claim 14, wherein said
`first value is a battery capacity Cfof said battery, and
`wherein said apparatus further comprises:
`means for measuring a time t,- for which said equip-
`ment operates at a first current I,-,
`means for calculating a first accumulated discharge
`value A of said battery by an equation of
`
`/‘= z.”i'1i"i
`I
`
`where a; is a weighting constant;
`means for calculating a difference between said val-
`ues Cj and A to produce said first remaining charge
`value CR=Cf—A,'
`means responsive to said detection signal for measur-
`ing a time t[7‘fOr which said equipment operates at
`a second current 1,7 and for calculating a second
`accumulated discharge value Arof said battery by
`an equation of
`
`«4T=2_0i-Ii-Ir,
`I
`
`means for calculating a difference between said val-
`ues Cf and A7-to produce said second remaining
`charge value CR7-= Cf-/fr,
`means for comparing said value Cgrwith said prede-
`termined value (Cm) to produce a change signal
`when said value Cgrexceeds said value Cm; and
`means responsive to said change signal for changing
`said value C/to a new value Cf.
`16. An apparatus as claimed in claim 15, further com-
`prising means for manually writing said value Cf into
`said storing means.
`17. An apparatus as claimed in claim 15, further com-
`prising means for manually resetting said value Cfto be
`a value Cfg.
`18. An apparatus as claimed in claim 14, wherein said
`first value is a weighting constant a,-, and wherein said
`storing means further comprises means for storing a
`battery capacity value Cfof said battery, and wherein
`said apparatus further comprises:
`means for measuring a time t,- for which said equip-
`ment operates at a first current 1,;
`means for calculating a first accumulated discharge.
`value A of said battery by an equation of
`
`
`
`.4 =2_a,'-I,--t,-I
`
`where a; is a weighting constant;
`means for calculating a difference between said val-
`ues Cfand A to produce said first remaining charge
`value CR = Cf—A,'
`means responsive to said detection signal for measur-
`ing a time t,-rfor which said equipment operates at
`a second current L7 and for calculating a second
`accumulated discharge value Arof said battery by
`an equation of
`
`Ar=Za,~-I,--I;
`1
`
`means for calculating a difference between said val-
`ues Cf and Arto produce said second remaining
`charge value CRr= Cf--AT,
`
`5
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`5,043,651
`
`10
`means for comparing said value Cgrwith said prede-
`termined value (Cm) to produce a change signal
`when said value CR1-exceeds said value Cm; and
`means responsive to said change signal for changing
`said value Cfto a new value Cf.
`19. An apparatus as claimed in claim 18, further com-
`prising means for manually writing said value a,- into
`said storing means.
`20. An apparatus as claimed in claim 18. further com-
`prising means for manually resetting said value a,- to a
`value a,-,,.
`21. An apparatus as claimed in claim 15, further com-
`prising means for manually resetting said first accumu-
`lated discharge value A to zero.
`22. An apparatus as claimed in claim 18, further com-
`prising means for manually resetting said first accumu-
`lated discharge value A to zero.
`23. An apparatus as claimed in claim 15, further com-
`prising means for detecting a current in said battery to
`produce a current detection signal as either said first
`current 1101' second current I,-,.
`24. An apparatus as claimed in claim 18, further com-
`prising means for detecting a current fiowing in said
`battery to produce 3 a current detection signal as either
`said first current I; or second current I,~,.
`25. A method of displaying a remaining charge value
`of a battery adapted to power electrical equipment,
`comprising the following steps of:
`detecting the output voltage of said battery to pro-
`duce a voltage detection signal when said output
`voltage falls below a predetermined threshold
`value;
`_
`storing a first value;
`calculating a first remaining charge value of said
`battery based on said first value;
`displaying said first remaining charge value:
`responsive to said voltage detection signal. calculat-
`ing a second remaining charge value of said battery
`based on said first value; and
`changing said first value when said second remaining
`charge value exceeds a predetermined value.
`26. A method as claimed in claim 25, wherein said
`step of storing comprises the step of storing a battery
`capacity Cf ‘of said battery as said first value, and
`wherein said method further comprises the steps of:
`measuring times, t,-, for which said equipment operates
`at first currents 1,;
`means for calculating a first accumulated discharge
`value A of said battery by an equation of
`
`A=Z_a-I,‘-I,‘
`I
`
`where a,- i