Power tool with light unit

• US 9,225,275 B2
• Filed: 05/18/2012
• Issued: 12/29/2015
• Est. Priority Date: 04/07/2010
• Status: Active Grant

• Current Assignee: Black & Decker Incorporated (Stanley Black & Decker, Inc.)
• Original Assignee: Black & Decker Incorporated (Stanley Black & Decker, Inc.)
• Inventors: Sterling, Brian C., Osborne, Stephen P., White, Paul S., Delcamp, Jeffery D., Forster, Michael K., Leh, Jason K.
• Primary Examiner(s): Chen, Sibin
• Application Number:
  US13/475,002
• Publication Number:
  US 20130063051A1
• Time in Patent Office: 1,320 Days
• US Class Current: 1/1
• CPC Class Codes: B25F 5/021 with guiding devices guiding devices for hand tools on stands or supports B25H1/0078
• CPC Class Codes: H01H 9/061 enclosing a continuously variable impedance
• CPC Class Codes: H02J 7/00041 in response to measured battery parameters, e.g. voltage, current or temperature profile
• CPC Class Codes: H02J 7/00047 with provisions for charging different types of batteries
• CPC Class Codes: H02J 7/0019 using switched or multiplexed charge circuits
• CPC Class Codes: H02J 7/007182 in response to battery voltage
• CPC Class Codes: H02J 7/04 Regulation of charging current or voltage
• CPC Class Codes: H02P 7/29 using pulse modulation
• CPC Class Codes: H05B 45/325 Pulse-width modulation [PWM]
• CPC Class Codes: H05B 47/16 by timing means
• CPC Class Codes: Y02B 20/40 Control techniques providing energy savings, e.g. smart controller or presence detection

Abstract

A power tool including a motor, light unit, and switch unit for selectively connecting the motor and light unit to a power source. A control module includes a controller coupled to a first electronic switch to control power delivery to the motor based on a position of the switch unit, and to a second electronic switch to control power delivery to the light source based on a position of the switch unit. A timer is configured to keep the light unit illuminated for a predetermined amount of time after the switch unit has been activated or deactivated. The control module also includes a boot circuit with a semiconductor switch that continues to deliver power to the controller and to the light unit when the switch unit is deactivated subsequent to being activated, to enable the light unit to remain illuminated after the switch unit has been deactivated.

Claims

1. A power tool comprising:

a housing able to be coupled to an electrical power source;

a motor contained in the housing and selectively connectable to the power source;

a light unit coupled to the housing and selectively connectable to the power source;

a switch unit coupled to the housing, wherein the switch unit can be selectively activated to cause power to be delivered to the motor and to the light unit, and selectively deactivated to cause power delivered to the motor to be interrupted;

a control circuit connected to the switch unit and to the light unit, and having a timer configured to keep the light unit illuminated for a predetermined amount of time after the switch unit has been activated or deactivated; and

a boot circuit connected to the control circuit, the boot circuit configured to connect the control circuit and the light unit to the power source when the switch unit is deactivated subsequent to being activated to enable the light unit to remain illuminated after the switch unit has been deactivated.

2. The power tool of claim 1, wherein the boot circuit connects the control circuit and the light unit to the power source at least until the earlier of expiration of the predetermined amount of time or until the switch unit has been activated a second time subsequent to being deactivated.

3. The power tool of claim 1, wherein the control circuit comprises a microcontroller programmed to control delivery of power to the motor and to the light unit.

4. The power tool of claim 3, wherein the control circuit comprises a first electronic switch between the motor and the power source, wherein the microcontroller controls operation of the first electronic switch to control power delivery to the motor.

5. The power tool of claim 4, wherein the control circuit comprises a second electronic switch between the light unit and the power source, wherein the microcontroller controls operation of the second electronic switch to control power delivery to the light unit.

6. The power tool of claim 1, wherein the boot circuit comprises a semiconductor switch having a first terminal connected to the power source on one side of the switch unit and a second terminal connected to the power source on an opposite side of the switch unit, so that closing the semiconductor switch causes power to be delivered to the control circuit and to the light unit.

7. The power tool of claim 6, wherein the control circuit causes power to flow through the semiconductor switch when the control circuit detects that the switch unit has been deactivated.

8. The power tool of claim 6, wherein the control circuit periodically interrupts operation of the boot circuit and determines whether the switch unit has been activated a second time subsequent to being deactivated before expiration of the predetermined amount of time.

9. The power tool of claim 8, wherein the control circuit interrupts power flow through the semiconductor switch if the control circuit determines that the switch unit has been activated a second time subsequent to being deactivated before expiration of the predetermined amount of time.

10. The power tool of claim 9, wherein the control circuit restarts or stops the timer if the control circuit determines that the switch unit has been activated subsequent to being deactivated before expiration of the predetermined amount of time.

11. A method of controlling illumination of a light unit on a power tool connectable to a power source, and having a motor and a switch unit, the method comprising:

providing a control circuit connectable to the power source for controlling power delivery to the motor and to the light unit;

determining when the switch unit has been activated;

when the switch unit is activated, enabling power to flow to the motor and to the light unit;

determining when the switch unit has been deactivated subsequent to being activated;

when the switch unit has been deactivated subsequent to being activated, interrupting power delivery to the motor, maintaining power delivery to the light unit for a predetermined amount of time after the switch unit has been activated or deactivated, and activating a boot circuit to continue delivering power to the control circuit and to the light unit.

12. The method of claim 11, wherein activating the boot circuit comprises keeping the boot circuit active until at least the earlier of expiration of the predetermined amount of time or the switch unit is activated a second time subsequent to being deactivated.

13. The method of claim 11, wherein the control circuit comprises a microcontroller programmed to drive the motor and the light unit.

14. The method of claim 11, wherein enabling power delivery to the motor comprises controlling operation of a first electronic switch between the motor and the power source to control power delivery to the motor.

15. The method of claim 11, wherein enabling power delivery to the light unit comprises controlling operation of a second electronic switch between the light unit and the power source to control power delivery to the light unit.

16. The method of claim 11, further comprising periodically interrupting operation of the boot circuit and determining whether the switch unit has been activated a second time subsequent to being deactivated before expiration of the predetermined amount of time.

17. The method of claim 16, further comprising deactivating the boot circuit if the switch unit has been activated a second time subsequent to being deactivated before expiration of the predetermined amount of time.

18. The method of claim 17, further comprising restarting or stopping a timer for the light unit if the switch unit has been activated a second time subsequent to being deactivated before expiration of the predetermined amount of time.

19. A control module for a power tool having a motor, a light unit, and a switch unit for selectively connecting the motor and the light unit to the power source, the control module comprising:

a controller coupled to a first electronic switch to control power delivery to the motor based on a position of the switch unit, and coupled to a second electronic switch to control power delivery to the light source based on a position of the switch unit, the controller including a timer configured to keep the light unit illuminated for a predetermined amount of time after the switch unit has been activated or deactivated; and

a boot circuit connected to the controller, the boot circuit including a semiconductor switch configured to continue to deliver power to the controller and to the light unit when the switch unit is deactivated subsequent to being activated, to enable the light unit to remain illuminated after the switch unit has been deactivated.

20. The control module of claim 19, wherein the controller periodically interrupts operation of the boot circuit and determines whether the switch unit has been activated a second time subsequent to being deactivated before expiration of the predetermined amount of time, and, if so, interrupts power flow through the semiconductor switch, and restarts or stops the timer.