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Lifting Device For An Overhead Projector Which Has A Constant Velocity During The Upward And Downward Movement

  • US 20110088982A1
  • Filed: 10/12/2010
  • Published: 04/21/2011
  • Est. Priority Date: 10/15/2009
  • Status: Abandoned Application
First Claim
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1. A lifting device, comprising:

  • a lifting unit;

    a drive unit connected with the lifting unit to control operation of the lifting unit; and

    a braking unit connected with the drive unit to control operation of the drive unit;

    wherein the braking unit includes;

    a microprocessor;

    a control circuit connected with the microprocessor;

    a changeover switch connected with the control circuit and the drive unit; and

    a control switch connected with the microprocessor and the changeover switch;

    the control circuit of the braking unit includes a first transistor, a second transistor, a first connecting terminal and a second connecting terminal;

    the first transistor of the control circuit is connected with a power supply and is connected with the first connecting terminal;

    the second transistor of the control circuit is connected with a ground side and is connected with the second connecting terminal;

    the control switch of the braking unit includes a relay;

    the relay of the control switch has a coil connected with the microprocessor.

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