Abstract:
The present invention discloses a smart speed control, power-saving and noise-reduction paper shredder, comprises an electric machine unit, a current inspection feedback unit, a gear-switching voltage-modulating and speed-regulating unit and a power supply, wherein an input terminal of the gear-switching voltage-modulating and speed-regulating unit is connected to an output terminal of the current inspection feedback unit, and an output terminal is connected to an input terminal of the electric machine unit; a paper shredder of the present invention applicable for an AC electric machine, an induction electric machine or a DC electric machine, wherein current required for paper shredding by the AC electric machine, the induction electric machine or the DC electric machine is detected, and the electric machine is adjusted to its best working condition, and a number of speeds including high, mid and low gears are provided and can be switched according to the actual load condition, so as to achieve the smart speed control, power saving and noise reduction effects.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a smart speed control, power-saving and noise-reduction paper shredder, and more particularly to a paper shredder having a knife or another cutting or tearing component to divide pieces of paper into shreds. 
     2. Description of the Related Art 
     Conventional paper shredder generally comes with a single rotation speed, a constant number of pieces of shredding paper, and a constant power for the operation of an electric machine. 
     If the paper shredder has one or two piece of paper remained or rotates idly, the electric machine will rotate at a higher rotation speed, make a louder noise, and consume more electric power. In a paper shredder electric machine as disclosed in P.R.C. Pat. No. 201113903Y, a speed control system is provided for adjusting the speed of the electric machine manually. In a paper shredder as disclosed in P.R.C. Pat. No. 201181926Y, an automatic gear control system detects the rotating speed of the electric machine and maintains the rotating speed of the electric machine automatically by optical controls, so as to overcome the aforementioned issues of the conventional paper shredder. However, both of the issued patents control the speed of the electric machine by changing the number of coils of the electric machine, and thus these patented technologies can be applied for AC electric machines only, but not for DC electric machines. 
     SUMMARY OF THE INVENTION 
     Accordingly, the primary object of the present invention is to provide a smart speed control, power-saving and noise-reduction paper shredder applicable for an AC electric machine, an induction electric machine or a DC electric machine, wherein current required for paper shredding by the AC electric machine, the induction electric machine or the DC electric machine is detected, and the electric machine is adjusted to its best working condition, and a number of speeds including high, mid and low gears are provided and can be switched according to the actual load condition, so as to achieve the smart speed control, power saving and noise reduction effects. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a block diagram of the present invention. 
         FIG. 2  shows a circuit diagram of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     With reference to  FIG. 1 , a paper shredder of the present invention comprises an electric machine unit  1 , a current inspection feedback unit  2 , a gear-switching voltage-modulating and speed-regulating unit  3  and a power supply  4 , wherein an input terminal of the gear-switching voltage-modulating and speed-regulating unit  3  is connected to an output terminal of the current inspection feedback unit  2 , and an output terminal is connected to an input terminal of the electric machine unit  1 , and the current inspection feedback unit  2  is provided for inspecting a current when the electric machine unit  1  shreds paper, comparing the inspection results, and transmitting the inspection results to the gear-switching voltage-modulating and speed-regulating unit  3 . After the gear-switching voltage-modulating and speed-regulating unit  3  receives the results, the gear is switched and the voltage is modulated automatically, and then the results are fed back to the electric machine unit  1  for adjusting the speed of the electric machine, so as to achieve the power saving and noise reduction effects. 
     With reference to  FIG. 2 , after a utility power AC IN is inputted, the electric power is supplied to the electric machine unit  1  and the gear-switching voltage-modulating and speed-regulating unit  3 , and the voltage used by the current inspection feedback unit  2  is a 12-volt to 24-volt power supply obtained by stepping down the voltage of the utility power AC IN and regulating the voltage. 
     The current inspection feedback unit  2  includes a dual-channel comparator B 1  and a dual-relay driver circuit B 2 , both composed of operational amplifiers, wherein a first control signal output terminal OUTPUT 1  and a second control signal output terminal OUTPUT 2  of the dual-channel comparator B 1  are coupled to a control terminal of the dual-relay driver circuit B 2 , and a sample voltage input terminal INPUT of the dual-channel comparator B 1  is connected to a current sample resistor R 19  of an electric machine of the electric machine unit  1 . 
     The dual-channel comparator B 1  includes comparators IC 1 A, IC 1 B, wherein the voltage reference of the comparator IC 1 A is set to V0 volts, the voltage reference of the comparator IC 1 B is set to V1 volts, and V0 is greater than V1. 
     If the sample voltage V2 is smaller than V1 and the voltages are compared by the comparator B 1 , the control signal output terminal OUTPUT 2 , OUTPUT 1  keeps and maintains a perfect low-level voltage at 0 volt. 
     If the sample voltage V2 is greater than V1 and smaller than V0 and the voltages are compared by the comparator B 1 , the control signal output terminal OUTPUT 2  will output a high-level voltage approximately equal to 12 volts, and the control signal output terminal OUTPUT 2  keep and maintain a perfect low-level voltage at 0 volt. 
     If the sample voltage V2 is greater than V0 and the voltage is compared by the comparator B 1 , the control signal output terminals OUTPUT 2 , OUTPUT 1  will output a high-level voltage approximately equal to 12 volts. 
     The dual-relay driver circuit B 2  includes an electronic switch circuit formed by connecting a first switch triode Q 1  and its coil KIA in series with a first relay K 1  of a primary circuit of the first switch triode Q 1 , and an electronic switch circuit formed by connecting a second switch triode Q 2  and its coil K 2 A in series with a primary circuit of a second relay K 2  of the second switch triode Q 2 , 
     The contact module comprised of the frequent-close contacts KIB, K 2 B and the frequent-open contacts KIC, K 2 C of the first relay K 1  and the second relay K 2  is connected to the gear-switching voltage-modulating and speed-regulating unit  3 . 
     If the control signal output terminals OUTPUT 2 , OUTPUT 1  keeps and maintains a perfect low-level voltage at 0 volt, then the second switch triode Q 2  and the first switch triode Q 1  will not be electrically conducted, and the coils K 1 A, K 2 A of the first relay K 1  and the second relay K 2  will not be electrically connected. 
     If the control signal output terminal OUTPUT 2  will output a high-level voltage approximately equal to 12 volts, the control signal output terminal OUTPUT 1  keep and maintain a prefect low-level voltage at 0 volt, then the second switch triode Q 2  and its coil K 2 A in series with a second relay K 2  will be electrically conducted, and the first switch triode Q 1  and its coil K 1 A in series with a first relay K 1  will not be electrically conducted. 
     If the control signal output terminals OUTPUT 2 , OUTPUT 1  will output a high-level voltage approximately equal to 12 volts, then the second switch triode Q 2  and the first switch triode Q 1  will be electrically conducted, and its coil K 1 A in series with a first relay K 1  and its coil K 2 A in series with a second relay K 2  will not be electrically conducted. 
     The electric machine unit  1  is a circuit unit C 1  of an AC electric machine or an induction electric machine, or a circuit unit C 2  of the DC electric machine. 
     The circuit unit C 1  of the AC electric machine or the induction electric machine includes the AC electric machine or the induction electric machine M and windings of the AC electric machine or the induction electric machine connected in series with a current sample resistor R 19  of the electric machine, and a terminal of the current sample resistor R 19  of the electric machine is connected to a sample voltage input terminal INPUT of the dual-channel comparator B 1 , and another terminal of the current sample resistor R 19  of the electric machine is connected to the ground. 
     The DC electric machine circuit unit C 2  includes the DC electric machine A, a rectifier circuit D 1  and windings of the DC electric machine A connected in series with a current sample resistor R 19 ′ of the electric machine, and a terminal of the current sample resistor R 19 ′ of the electric machine is connected to the sample voltage input terminal INPUT of the dual-channel comparator B 1 , and another terminal of the current sample resistor R 19 ′ of the electric machine is connected to the ground. 
     The gear-switching voltage-modulating and speed-regulating unit  3  includes a thyristor Q 3  and its trigger control circuit, and an output circuit comprised of R 16  and C 7 , wherein the trigger control circuit includes a bidirectional diode D 9  and a thyristor conduction time adjusting circuit, thyristor conduction time adjusting circuit includes a plurality of voltage division resistors R 13 , R 14 , R 15  and filter capacitors C 8 , C 9  and a first relay installed in a current inspection feedback unit  2 , and a contact module comprised of frequent-close contacts KIB, K 2 B and frequent-open contacts KIC, K 2 C of a second relay KI, K 2 , and an output terminal MG 1  of an output circuit comprised of R 16 , C 7  is connected to a voltage input terminal MG, MG 2  of the electric machine unit  1 . 
     The working process of the voltage output terminal MG 1  of the gear-switching voltage-modulating and speed-regulating unit  3  connected in series with a voltage input terminal MG of the circuit unit C 1  of the AC electric machine or the induction electric machine is described as follows. The working process of the voltage output terminal MG 1  of the gear-switching voltage-modulating and speed-regulating unit  3  is substantially the same as the working process of the voltage input terminal MG 2  connected in series with the circuit unit C 2  of the DC electric machine. 
     If the coils K 1 A, K 2 A of the first and second relay K 1 , K 2  are not electrically conducted, the first relay K 1  and the second relay K 2  will be situated at the frequent-close contacts K 1 B, K 2 B respectively, and a discharge circuits composed of selected resistors R 13 , R 13  and C 8  is used for electrically conducting a resistor R 15  and a bidirectional diode D 9  to control the electric conduction of the thyristor Q 3  in order to change the voltage of the voltage output terminal MG 1  of the thyristor Q 3 . Since the voltage output terminal MG 1  is connected in series with the voltage input terminal MG of circuit unit C 1  of the AC electric machine or the induction electric machine in order to change the speed of the AC electric machine or the induction electric machine A, the speed control effect can be achieved. 
     If the coil K 2 A of the second relay K 2  is electrically conducted and the coil K 1 A of the first relay K 1  is not electrically conducted, then the first relay K 2  will be situated at the frequent-open contact K 2 C, and the relay K 1  will be situated at a frequent-close contact K 1 B, and a discharge circuit composed of selected resistors R 12 , R 13  and connected in parallel with a circuit and a C 8  circuit which are connected in parallel with the selected resistors R 12 , R 13  is used for electrically conducting a resistor R 15  and a bidirectional diode D 9  to control the electric conduction of the thyristor Q 3 , so as to change the voltage of the voltage output terminal MG 1  of the thyristor Q 3 . Since the voltage output terminal MG 1  is connected in series with the voltage input terminal MG of the circuit unit C 1  of the AC electric machine or the induction electric machine, the speed of the AC electric machine or the induction electric machine A can be changed to achieve the speed control effect. 
     If the coils K 1 A, K 2 A of the first and second relays K 1 , K 2  are electrically conducted, the first relay K 1  and the second relay K 2  will be situated at the frequent-open contacts K 1 C, K 2 C respectively, and the utility power AC 2  is passed through the frequent-open contact K 1 C of the first relay K 1  to the voltage output terminal MG 1  of the thyristor Q 3  to change the voltage of the voltage output terminal MG 1 . Since the voltage output terminal MG 1  is connected in series with the voltage input terminal MG of the circuit unit C 1  of the AC electric machine or the induction electric machine, the speed of the AC electric machine or the induction electric machine A can be changed to achieve the speed control effect. 
     In conclusion, the present invention smart speed control, power-saving and noise-reduction paper shredder provides a high generality that can be used for the AC electric machines and the induction electric machines, as well as for the DC electric machines. The invention can achieve the smart speed control, power saving, and noise reduction effects.