Battery powered electronic device and control method therefor

• US 20020171400A1
• Filed: 03/06/2002
• Published: 11/21/2002
• Est. Priority Date: 03/08/2001
• Status: Active Grant

• Current Assignee: 138 East LCD Advancements Limited (Vector Capital Corporation)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Fujisawa, Teruhiko, Kitazawa, Koji, Koyama, Shunsuke
• Granted Patent: US 6,744,698 B2
• Time in Patent Office: Days
• US Class Current: 320/135
• CPC Class Codes: G04G 19/08 Arrangements for preventing voltage drop due to overloading the power supply
• CPC Class Codes: G04G 21/04 using radio waves radio-controlled time-pieces G04R
• CPC Class Codes: G04R 60/10 inside cases
• CPC Class Codes: H02J 7/0063 with circuits adapted for supplying loads from the battery
• CPC Class Codes: H02J 7/007184 in response to battery voltage gradient

Abstract

A first control unit 110 and second control unit 120 are disposed to a portable data terminal 100 having a heavy load group 140 and light load group 150. The first control unit 110 detects the output voltage of a secondary battery 105 and controls power supply to the heavy load group 140 by switching a first switch S1. When the first control unit 110 stops power supply to the heavy load group 140, it outputs a low level control signal CC to the second control unit 120. The load of driving the second control unit 120 is designed to be smaller than the load of driving the first control unit 110. When the control signal CC is received, the second control unit 120 starts detecting the output voltage of the secondary battery 105, and stops power supply to the switch light load group 150 and first control unit 110 if the output voltage is detected to drop to a preset threshold voltage.

Claims

1. An electronic device characterized by comprising:

a battery;

multiple load units driven by the battery;

a first control unit for limiting driving part of the multiple load units by the battery when the battery output voltage drops to a first threshold voltage while driving the multiple load units; and

a second control unit for stopping driving at least part of the multiple load units and the first control unit when the battery output voltage drops to a second threshold voltage after driving part of the multiple load units is limited.

2. An electronic device as described in claim 1, characterized by the multiple load units having a heavy load unit and a light load unit with less power consumption than the heavy load unit;

and

the first control unit stops driving the heavy load unit with the battery when the battery output voltage drops to the first threshold voltage while driving the multiple load units.

3. An electronic device as described in claim 1 or 2, characterized by the first control unit outputting an activation signal to start the second control unit when the battery output voltage drops to the first threshold voltage while driving the multiple load units.

4. An electronic device as described in claim 2, characterized by a difference between voltage drop due to internal resistance of the , battery when driving the light load unit, first control unit, and second control unit, and voltage drop due to internal resistance of the battery when driving only the second control unit, is smaller than the voltage detection resolution of the second control unit.

5. An electronic device as described in claim 2, characterized by the heavy load unit having a wireless communication unit;

the first control unit having a means for controlling so that the heavy load unit is intermittently driven by the battery, and

a means for terminating intermittent drive of the heavy load unit by the battery when the battery output voltage drops to the first threshold voltage while the heavy load unit is driven by the battery; and

the second control unit comprises a means that responds to change in the battery output voltage faster than the first control unit, and interrupts power supply from the battery to the first control unit and terminates intermittent drive of the heavy load unit when the battery output voltage drops to or below a third threshold voltage in a period in which the heavy load unit is not driven by the battery while the heavy load unit is being intermittently driven by the battery.

6. An electronic device as described in claim 5, characterized by comprising a third control unit that is a means that responds to change in the battery output voltage faster than the first control unit, and prohibits driving the heavy load unit by the battery when the battery output voltage while the heavy load unit is being driven by the battery drops to a fourth threshold voltage that is lower than the first threshold voltage.

7. An electronic device as described in claim 2, characterized by the light load unit including a light load for communicating arrival of a recharge time or battery replacement time;

and

the first control unit drives the light load for communicating arrival of a recharge time or battery replacement time when the battery output voltage drops to the first threshold voltage while driving the multiple load units.

8. An electronic device as described in claim 7, characterized by the light load for communicating arrival of the recharge time being a display device for reporting arrival of the recharge time by displaying a text message or image.

9. An electronic device as described in claim 7, characterized by the light load for communicating arrival of the recharge time being an alarm device for reporting arrival of the recharge time by producing an alarm sound or vibration.

10. An electronic device as described in claim 1, characterized by the load units including a wireless communication function unit driven by the battery for intermittent two-way wireless communication with an external device;

and

the electronic device comprises;

a detection means for detecting a condition of the battery; and

a fourth control unit for prohibiting driving a specific load unit of the multiple load units other than the wireless communication function unit if wireless communication occurs when the detection means detects that the battery condition has reached a specific state.

11. An electronic device as described in claim 10, characterized by the detection means being a circuit for detecting the battery output voltage.

12. An electronic device as described in claim 10, characterized by the detection means being a circuit for detecting remaining battery capacity.

13. An electronic device as described in claim 10, characterized by the fourth control unit determining the load unit or combination of plural load units to be prohibited from driving during wireless communication according to the battery state detected by the detection means.

14. An electronic device as described in claim 10, characterized by being able to assume a low power consumption mode for wireless communication of synchronization signals at a specific period for maintaining synchronization of a wireless communication network formed with an external device, or an active mode for actual wireless data communication with the external device;

wherein the fourth control unit prohibits driving one or multiple load units other than the wireless communication function unit when in the active mode and during wireless communication of the synchronization signals in the low power consumption mode.

15. An electronic device as described in claim 10, characterized by wireless communication using Bluetooth (TM).

16. An electronic device as described in claim 10, characterized by the load unit prohibited from driving during wireless communication including any one of the following function units:

a buzzer communication function unit dependent upon driving a buzzer, a vibration communication function unit dependent upon driving a motor for a vibrator, a light-emitting communication function unit dependent upon driving an LED, and a display function unit dependent upon driving a liquid crystal display unit.

17. A control method for an electronic device characterized by comprising:

a detection step for detecting the output voltage of a battery disposed as the power source in an electronic device having a heavy load unit with high power consumption and a light load unit with low power consumption;

a first control step for limiting driving the heavy load unit by the battery when the battery output voltage drops to a first threshold voltage; and

a second control step for stopping driving the heavy load unit and light load unit by the battery when the battery output voltage drops to a second threshold voltage after driving a heavy load unit is limited.

18. A program run on a computer for controlling an electronic device, comprising:

a detection step for detecting the output voltage of a battery disposed as the power source in an electronic device having a heavy load unit with high power consumption and a light load unit with low power consumption;

a first control step for limiting driving the heavy load unit by the battery when the battery output voltage drops to a first threshold voltage; and

a second control step for stopping driving the heavy load unit and light load unit by the battery when the battery output voltage drops to a second threshold voltage after driving a heavy load unit is limited.

19. A computer-readable storage medium for storing a program run on a computer for controlling an electronic device, comprising:

a detection step for detecting the output voltage of a battery disposed as the power source in an electronic device having a heavy load unit with high power consumption and a light load unit with low power consumption;

a first control step for limiting driving the heavy load unit by the battery when the battery output voltage drops to a first threshold voltage; and

a second control step for stopping driving the heavy load unit and light load unit by the battery when the battery output voltage drops to a second threshold voltage after driving a heavy load unit is limited.