Patents Assigned to Defond Manufacturing Limited
  • Patent number: 6590175
    Abstract: An electrical switch, such as a rocker switch, includes a casing, three fixed contacts, each contact having an inner end, and an operating rocker movable between an operating position and a non-operating position. The switch includes a moving contact movable by the rocker to make and break electrical connection between the inner ends of a first pair of the fixed contacts (connectable to a load and a power source) while the rocker is in the operating and non-operating positions, respectively. Also included are a light bulb, lighting to indicate when the rocker is in the operating position, and an associated resistor. The light bulb and resistor are connectable in series across the inner ends of a second pair of the fixed contacts (connectable to a power source) when the rocker is in the operating position. The resistor is fixed, has a body, and has first and second terminals.
    Type: Grant
    Filed: June 3, 2002
    Date of Patent: July 8, 2003
    Assignee: Defond Manufacturing Limited
    Inventor: Hin Ming Lam
  • Publication number: 20030043004
    Abstract: A circuit breaker (100) for use between a load and a power source, comprising at least two movable contacts (212/222) for electrical connection to the load and power source respectively, a movable contact holder (220) holding the first contact (222), a first spring (224) biassing the contact holder (220) to move, and an actuator (210) arranged to move the second contact (212) into contact with the first contact (222). A locking frame (230) is arranged to lock the contact holder (220) and in turn the first contact (222) at a specific position into the path of movement of the second contact (212), against the action of the spring (224), for contact by the second contact (212). The locking frame (230) is supported for pivotal movement between a first position locking the contact holder (220) in said specific position and a second position releasing the contact holder (220) from said specific position. A second spring (238) biasses the locking frame (230) towards the second position.
    Type: Application
    Filed: August 28, 2001
    Publication date: March 6, 2003
    Applicant: Defond Manufacturing Limited
    Inventor: Raymond Wai Hang Chu
  • Patent number: 6483063
    Abstract: An electrical switch includes a body, three control terminals and a common terminal for external connection and a movable contact for establishing connection between the control terminals and the common terminal. The movable contact has one end acting as the common terminal and three opposite ends that pivot to connect to the control terminals, respectively. Each opposite end is pivotable between a first position in contact with the corresponding control terminal and a second position separated from the corresponding control terminal. A switching member is supported for pivoting the opposite ends of the movable contact to establish the connection. A single metal heat sink is located within the body for contact by the opposite ends of the movable contacts when the movable contacts are in the second positions.
    Type: Grant
    Filed: March 14, 2001
    Date of Patent: November 19, 2002
    Assignee: Defond Manufacturing Limited
    Inventor: Raymond Wai Hang Chu
  • Patent number: 6388408
    Abstract: A device for sensing motor current for over-current protection in an electric power tool. The tool includes an electric motor supplied with electrical power via a live cable and incorporates over-current protection including a tripping circuit with a current sensor associated with the live cable. The device includes a toroid of the sensor and two cable segments connected in parallel to a section of the live cable such that the motor current will be distributed among the cable segments and live cable section in respective proportions. The toroid extends around one cable segment for sensing the respective proportion of the motor current.
    Type: Grant
    Filed: December 18, 2000
    Date of Patent: May 14, 2002
    Assignee: Defond Manufacturing Limited
    Inventor: Raymond Wai Hang Chu
  • Patent number: 6340926
    Abstract: A power plug includes a plug body having opposite sides and an end, terminal prongs extending from the end of the plug body, and a built-in circuit breaker. The circuit breaker is operable between a normal condition enabling the power plug to connect a load to a power source and a tripped condition disconnecting the load upon the detection of a circuit fault. The circuit breaker includes at least two members at respective opposite sides of the plug body which are simultaneously movable between a first position corresponding to the normal condition and a second position corresponding to the tripped condition. The members provide an indication of the operating condition of the circuit breaker viewable on both sides of the plug body.
    Type: Grant
    Filed: December 22, 1999
    Date of Patent: January 22, 2002
    Assignee: Defond Manufacturing Limited
    Inventor: Raymond Wai Hang Chu
  • Patent number: 6281482
    Abstract: An electrical switch including a body, fixed and movable contacts in the body, a principal switching member supported by the body for movement between ON and OFF positions, and a subsidiary switching member supported by the principal switching member for movement in directions different from directions of movement of the principal switching member. The principal switching member has an inner part providing a switching profile to operate the movable contacts with respect to the fixed contacts for switching. The subsidiary switching member has an inner part positioned at the switching profile for changing the switching profile while the principal switching member is in the ON position. The switch may be used to control the operation of a hair dryer to provide, in particular, a COOL shot by operation of the subsidiary switching member.
    Type: Grant
    Filed: July 13, 2000
    Date of Patent: August 28, 2001
    Assignee: Defond Manufacturing Limited
    Inventor: Raymond Wai Hang Chu
  • Patent number: 6274828
    Abstract: An on-off switch for an electric power hand tool such as an electric saw. The switch has a body, a switching mechanism within the body, and a spring-loaded trigger supported by the body for movement between a first position to turn on the switching mechanism and a second position to turn off the switching mechanism. The switch includes a movable locking device resiliently biased by a spring for locking the trigger in the second position against accidental switching on. The trigger and locking device include respective parts for abutment with each other to lock the trigger in the second position.
    Type: Grant
    Filed: February 22, 2000
    Date of Patent: August 14, 2001
    Assignee: Defond Manufacturing Limited
    Inventor: Raymond Wai Hang Chu
  • Patent number: 5815363
    Abstract: A circuit breaker comprising a switch for controlling the connection of a load to a power source, the switch having a fixed contact and a movable switch contact supported on a pivotable switching member and resiliently biased away from the fixed contact. The circuit breaker includes a solenoid having a first winding for initially moving the movable contact towards the fixed contact and a second winding for holding the movable contact against the fixed contact, a fault detection circuit adapted to detect a fault at the load and in response to disable the solenoid, and a reset switch for initially enabling energization of the first winding and when the movable contact is sufficiently close to or in contact with the fixed contact for subsequently enabling energization of the second winding. The reset switch is arranged to be operated by a part of the switching member by virtue of the movement of the movable contact in order to control energization of the windings.
    Type: Grant
    Filed: October 1, 1996
    Date of Patent: September 29, 1998
    Assignee: Defond Manufacturing Limited
    Inventor: Raymond Wai Hang Chu
  • Patent number: 5810109
    Abstract: An electrical switch comprising a body having two switch terminals, a switching member having an a side and a window provided at the side. The switching member is supported by the body for pivotal movement between a first position in which the terminals are electrically interconnected and a second position in which the terminals are electrically disconnected. The switch includes an indicator supported behind and arranged for exposure through the window of the switching member to indicate the switching condition of the switch through relative movement between the switching member and the indicator. The indicator has a single surface to indicate said switching condition.
    Type: Grant
    Filed: December 17, 1996
    Date of Patent: September 22, 1998
    Assignee: Defond Manufacturing Limited
    Inventor: Raymond Wai Hang Chu