WO1990013189A1

WO1990013189A1 - Low battery indicator

Info

Publication number: WO1990013189A1
Application number: PCT/US1990/001653
Authority: WO
Inventors: Courtney St. George Henry; Pamela Ann Rakolta; Silvia Marina Viteri
Original assignee: Motorola, Inc.
Priority date: 1989-04-17
Filing date: 1990-03-29
Publication date: 1990-11-01
Also published as: KR920700505A

Abstract

An electrical device has a power supply (32) which has a varying electrical condition. In response to the varying electrical condition equaling a predetermined electrical condition an indication is generated. The indication indicates the elapsed time or the consumed power since detection of the predetermined electrical condition. In the preferred embodiment, the electrical device is a selective call paging receiver (20) and the power supply is a battery (32).

Description

Low Battery Indicator

Background of the Invention

This invention relates generally to the area of a power supply indicator used in conjunction with an electrical device. More particularly, this invention relates to an improved low battery indicator for use, though not exclusively, with a paging receiver.

Paging receivers are electrical devices which are powered by battery power supplies. As the battery discharges a paging receiver generates a low battery indication. In many cases, paging receivers continue to operate properly for several days after the low battery indication. It is desirable to enable the user of the paging receiver to expend the total capacity of the battery remaining after the low battery indicator while still providing ample low battery indications in order that a new battery or a battery recharge may be obtained.

With the advent of lower power and smaller paging receivers, the feasibility of smaller, lower capacity batteries is becoming apparent . Such batteries suffer from irregular performance towards the end of the life of the battery. Current pagers use many types of battery technologies such as nickel-cadmium, alkaline, carbon-zinc, mercury and zinc-air. Each battery technology has different characteristics, particularly towards the end of the life of the battery. Additionally, advances in the battery manufacturing industry are continually improving battery performance. For example, today's alkaline battery has substantially more capacity than the alkaline battery of just two years prior.

Since the usable life of a paging receiver is five or more years and since a particular paging receiver may operate on several different battery technologies in it's life span, it is difficult to provide a reliable indication that the battery on which the paging receiver operates is approaching the end of its life and approximately how much capacity is left in the battery. It is also difficult to predict what advances will be made in battery technology during the usable life of a paging receiver.

Prior art low battery indicators have operated simply to display "LO CELL" when the battery voltage reaches a predetermined voltage. Still other low battery indicators would generate only a short tone burst, which if not heard by the user would go unnoticed. Yet still another low battery indicator would generate a continuous alert tone. These prior art low battery indicators provide no indication as to the time since the low battery state has been detected, and further provide no means for determining the battery capacity remaining.

Summary of the Invention It is therefore an object of the present invention to overcome the aforementioned disadvantages .

It is an object of the present invention to provide a low battery indicator which corresponds to the elapsed time since the detection of a low battery state.

It is yet another object of the present invention to provide a low battery indicator which indicates a value which corresponds to the consumed battery capacity since the detection of the low battery state.

It is still another object of the present invention to provide an alert indicating that the low battery indicator has reached a predetermined value.

In accordance with the present invention, an electrical device comprises a power supply means having a varying electrical condition while providing electrical power to the electrical device, a sensing means coupled to said power supply means for sensing a predetermined electrical condition, and an indicating means responsive to said sensing means for generating a duration signal indicative of the duration of the predetermined electrical condition.

In accordance with the present invention, an electrical device comprises a power supply means having a varying electrical condition while providing electrical energy to the electrical device, a sensing means coupled to said power supply means for sensing a predetermined electrical condition, and an indicating means for generating a consumption signal indicative of the electrical energy consumed by the electrical device in response to the sensing of the predetermined electrical conditio .

Brief Description of the Drawings Figure 1 shows a paging receiver operating in accordance with the present invention.

Figure 2 shows an example of a low battery display in accordance with the present invention.

Figure 3 shows a flowchart detailing a first embodiment operating in accordance with the present inventio .

Figure 4 shows a flowchart detailing a second embodiment operating in accordance with the present invention.

Figure 5 shows a flowchart detailing a third embodiment operating in accordance with the present inventio . Description of a Preferred Embodiment

Figure 1 shows a paging receiver operating in accordance with the present invention. Paging receiver 20 includes a receiving means 22 which receives and demodulates paging information modulated upon an RF carrier. The paging information may be included within one of several known paging protocols such as the GSC or POCSAG paging protocols . The demodulated information is decoded by decoding means 24. If an address matching an address assigned to the paging receiver is decoded, an alert is generated on alert means 26. If the address has message information associated with it, the message information may be displayed on message display means 28. Additionally, OFF/ON switch 30 disables and enables the process of receiving and demodulating information by the paging receiver. The paging receiver is powered by a power supply means or battery 32, which has a varying electrical condition, or output voltage as the capacity of the battery is utilized by the paging receiver. The electrical condition of the battery is sensed by a sensing means 34 which includes a voltage comparison means for comparing the battery voltage with a predetermined voltage and generating a signal in response to the equality. The output of the sensing means is coupled to an indicating means 36 which in a first and second embodiment, generates an indication of the elapsed time since the sensing or detection of the low battery. Or in a third embodiment, indicating means 36 monitors the operation of the means 22, 24, 26, 28, and 30 in order to produce a signal indicative of the power consumed since the low battery. Indicating means 36 uses a time base 38 in either the first or second embodiments in order to produce the signal. The signal from- indicating means 36 may be displayed on condition display means 40. Additionally, when the signal from the indicating means reaches a predetermined value, the indicating means may cause alert means 26 to generate an audio signal. Message display 28 and condition display 40 may be combined on a common display means 42 which preferably includes a liquid crystal display (LCD) . Indeed the condition display may be displayed on the same LCD segments as the message display when the message display is inactive.

The decoder 24, indicating means 36 and time base 38 may be implemented in a host microcomputer 44. A preferred microcomputer is the Motorola MC146805H2. US patent 4,755,816 to DeLuca shows a microcomputer controlled pager which combined with the description herein provides an enabling description of the invention. Said patent is hereby incorporated by reference.

Figure 2 shows an example of a low battery display in accordance with the present invention. Figure 2 shows the common display means 42 showing the condition display. The words "LO CELL" are displayed indicating that the low battery condition has been sensed. The value "2794" is displayed indicating that the signal generated the indicating means 36 has the corresponding value. Common display means 42 may appear on the top of a paging receiver such as the Motorola Bravo paging receiver which is known and used on six of the seven continents.

Figure 3 shows a flowchart detailing a first embodiment operating in accordance with the present invention. The flowchart of figure 3 operates in a known multi-tasking software environment within a microcomputer within a paging receiver. Step 100 blanks the condition display. Step 102 continually checks for a low battery condition. In response to a low battery condition, step 104 generates a low battery alert. Means for performing steps 102 and 104 are well known in the prior art. In step 106, a "0000" is displayed on condition display 40. Additionally, "LO CELL" may be continuously displayed. Step 108 checks if OFF/ON switch is in the OFF state, thereby checking if the pager is switched OFF. If true, step 108 loops continuously until the pager is switched back ON. When the pager is switched ON, step 110 delays for one minute and then step 112 increments the condition display. Step 114 checks if the condition display is equal to a predetermined value of 5000, if not step 108 is returned to, if so a second low battery alert is generated in step 116 and then step 108 is returned to. Step 100 is returned to in response to replacing or recharging the batter .

It can be appreciated that the delay of step 110 and the value of step 114 are predetermined and may be varied while remaining within the scope of the invention. Furthermore, the alert of step 116 may be a short tone burst or a long sequence of tones.

Figure 3 shows an embodiment of the invention wherein the condition display shows a count increasing with the number of minutes since the detection of a low battery condition. Then when the count reaches a value of 5000, an alert is. generated. If the pager is switched off, the count is maintained until the pager is switched back on, where the count resumes.

A person using this invention would learn that for example, present alkaline batteries provide for operation of the paging receiver up to a count of 6500, as battery technology improves in future years, the pager may safely operate up to a count of 8500. In another example, a person replacing an alkaline battery with a NiCad battery would learn that the pager would only operate to a count of 1200 before a recharge is needed.

It can be further appreciated that the value "5000" and/or the delay "one minute" gives an indicator that the battery capacity is substantially depleted. This value may be stored in programmable non-volatile memory and may be changed as battery technology improves or in response to the user changing battery technologies . The value may be user selectable, programmed by the user, or programmable over the air using message information received by the pager. Techniques for programming programmable non¬ volatile memory are well known in the state of the art of paging receivers.

Figure 4 shows a flowchart detailing a second embodiment operating in accordance with the present invention. The flowchart of figure 4 operates in a multi¬ tasking software operating environment within a microcomputer within a paging receiver. In step 130, the condition display is blanked. Step 132 continually checks for a low battery condition. In response to a low battery condition, step 134 generates a low battery alert. Means for performing steps 132 and 134 are well known in the prior art. In step 136, a "7500" is displayed on condition display 40. Additionally, "LO CELL" may be continuously displayed also. Step 138 checks if OFF/ON switch is in the OFF state, thereby checking if the pager is switched OFF. If true, step 138 returns to step 140, thereby awaiting for the pager to be switched back on causing the flowchart to restart at the beginning. When the pager is switched ON, step 140 delays for ten seconds and then step 142 decrements the condition display. Step 144 checks if the condition display is equal to 0000, if not step 138 is returned to, if so a second low battery alert is generated in step 146 and condition display remains displaying "0000" indefinitely.

It can be appreciated that the delay of step 140 and the value of step 136 are predetermined and may be varied while remaining within the scope of the invention. Furthermore, the alert of step 146 may be a short tone burst of a long sequence of tones.

Figure 4 shows an embodiment of the invention wherein the condition display shows a count that counts down from a predetermined value and stops when the value equals 0000. An alert is generated in response to the 0000 value. If the pager is switched off, the initial condition is returned to. This finds particularly useful application with battery technologies that are capable of recovering additional voltage when not loaded by the paging receiver. Similar to Figure 3, the value of step 136 and/or the delay of step 140 may be stored in modifiable programmable non¬ volatile memory.

Figure 5 shows a flowchart detailing a third embodiment operating in accordance with the present invention. The flowchart of figure 5 operates in a multi¬ tasking software operating environment within a microcomputer within a paging receiver. In step 160, the condition display is blanked and a value "X" generated by the indicating means is initialized to "0000.000". Steps 160 and 162 continually checks for a low battery condition. In response to a low battery condition, step 164 checks if the alert means is active, if so step 166 add 0.300 to X. If step 164 is true or false, step 168 checks if the receiving means is active, if so step 170 add 0.023 to X. If step 168 is true of false, step 172 checks if the message display means is active, if so step 174 add 0.008 to X. If step 172 is true or false, step 176 checks if the microcomputer is in the high speed mode, thereby drawing higher current, if so step 178 adds 0.005 to X. If step 176 is true or false, step 180 checks if the pager is switched OFF. If true step 182 adds 0.001 to X and then delays for one second before returning to step 180. Steps 180 and 182 are repeated until the pager is switched ON. When the pager is switched ON, the program proceeds from step 180 to step 184 to first add 0.001 to X, and second display the integer value of X with the digits to the right of the decimal point truncated, and third step 184 delays for 0.1 seconds. Then in step 186, the integer value of X is checked to be equal to a value of 700, if so step 188 generates a low battery alert such as steps 116 and 146. From either step 186 or 188, the program returns to step 164. In response to replacing or recharging the battery the program returns to step 160.

Figure 5 shows an embodiment of the invention where the condition display displays a value corresponding to the power consumed since the detection of the low battery state. The values in steps 166, 170, 174, 178, 182 and 184 are predetermined and attempt to correlate to the relative power consumed by the corresponding means while activate during the delay specified by steps 182 or 184. A low battery alert is generated when a predetermined value, corresponding to a certain amount of power, has been reached. As in figure 3, the values and delays of figure 5 may be stored in programmable non-volatile memory and reprogrammed in response to several known techniques.

It will be appreciated that the invention has been described above by way of example only and that modifications to the above may be made without departing from the spirit and scope of the invention.

What is claimed is:

Claims

1. An electrical device comprising: power supply means having a varying electrical condition while providing electrical power to the electrical device; sensing means coupled to said power supply means for sensing a predetermined electrical condition; and indicating means responsive to said sensing means for generating a duration signal indicative of the duration of the predetermined electrical condition.

2. The electrical device of claim 1 wherein said power supply means includes a battery and the varying electrical condition corresponds to the output voltage of the battery.

3. The electrical device of claim 2 wherein the predetermined electrical condition corresponds to the output voltage crossing a predetermined value.

4. The electrical device of claim 2 wherein the duration signal includes a count which increases with the time since the sensing of the predetermined electrical condition.

5. The electrical device of claim 2 wherein the duration signal includes a count which decreases with the time sine sensing of the predetermined electrical condition.

6. The electrical device of claim 1 further comprising: power consuming means coupled to said power supply means; and power control means for activating and deactivating said power consuming means, wherein said indicating means being further responsive to said power control means generates the duration signal indicative of the duration of the activation of said power control means since the sensing of the predetermined electrical condition.

7. The electrical device of claim 1 further comprising display means for displaying the duration signal in a readable manner.

8. The electrical device of claim 1 further comprising alert means generating an alert signal in response the generation of the duration signal.

9. The electrical device of claim 1 further comprising alert means for generating an alert signal in response to the generation of the duration signal for a predetermined duration.

10. The electrical device of claim 1 wherein the electrical device includes a selective call receiver including: receiver means for periodically activating in order to receiving message information on a radio frequency carrier; and decoding means for selectively processing the received message information, wherein said receiving means and said decoding means are powered by said power supply means, and wherein said sensing means senses said power supply means in response to the receiving means being activated.

11. An electrical device comprising: power supply means having a varying electrical condition while providing electrical energy to the electrical device; sensing means coupled to said power supply means for sensing a predetermined electrical condition; and indicating means for generating a consumption signal indicative of the electrical energy consumed by the electrical device in response to the sensing of the predetermined electrical condition.

12. The electrical device of claim 11 wherein said power supply means includes a battery, the varying electrical condition corresponds to the output voltage of the battery, and the predetermined electrical condition corresponds to the output voltage crossing a predetermined value.

13. The electrical device of claim 11 further comprising display means for displaying the consumption signal in a readable manner.

14. The electrical device of claim 11 further comprising alert means for generating an alert signal in response to the consumption signal exceeding a predetermined value.

15. The electrical device of claim 11 wherein the electrical device includes a selective call receiver including: receiving means for receiving and demodulation message information modulated upon a radio frequency carrier, said receiving means periodically activating and deactivating while receiving and demodulating message information, wherein said indicating means increases the consumption signal by a first amount in response to said receiving means being active during a first time period or by a second amount in response to the receiving means being inactive during the first time period.

16. The selective call receiver of claim 15 further including: decoding means for selectively processing the demodulated message information, and for operating in a reduced power mode in response to said receiving means being inactivated, wherein said indicating means increases the consumption signal by a third amount in response to said decoding means processing the demodulated information during the a second time period or by a fourth amount in response to the decoding means operating in a reduced power mode during the second time period.

17. The selective call receiver of claim 16 further said decoding means includes a microcomputer.

18. The selective call receiver of claim 16 further including: display means for displaying message information received on the radio frequency carrier while active and for operating in a reduced power state while inactive, wherein said indicating means increases the consumption signal by a fifth amount in response to said display means being active during a third time period or by a sixth amount in response to the display means being inactive during the third time period.

19. The selective call receiver of claim 15 further including: alert means for alerting the reception of message information received on the radio frequency carrier while active and for operating in a reduced power state while inactive, wherein said indicating means increases the consumption signal by a seventh amount in response to said alert means being active during a fourth time period or by an eighth amount in response to the display means being inactive during the fourth time period.

20. The selective call receiver of claim 11 further including: power consuming means coupled to said power supply means; and power control means for activating and deactivating said power consuming means, wherein said indicating means increases the consumption signal by a ninth amount in response to said alert means being active during a fifth time period or by a tenth amount in response to the display means being inactive during the fifth time period.

21. A method of indicating the duration of a predetermined electrical condition in an electrical device comprising the steps of: providing electrical power to the electrical device from a power supply means having a varying electrical condition; sensing a predetermined electrical condition; and generating a duration signal indicative of the duration of the predetermined electrical condition.

22. A method of indicating the electrical energy consumed by an electrical device in response to the sensing of a predetermined electrical condition comprising the steps of: providing electrical power to the electrical device from a power supply means having a varying electrical condition; sensing a predetermined electrical condition; and generating a consumption signal indicative of the electrical energy consumed by the electrical device in response to the sensing of the predetermined electrical condition.