Patent Publication Number: US-2018050344-A1

Title: Paper shredder ac/dc motor controller

Description:
BACKGROUND 
     1. Field of the Invention 
     The present invention relates to paper shredders and, in particular, to paper shredder controllers. 
     2. Background Art 
     Present paper shredder controllers contain at least one programmable digital integrated circuits (chips), which require programming, timing analysis, and functional testing. The presence of the chips impose a cost in man-hours, which can add to the cost of the device. What is desired is a paper shredder controller without a programmable digital IC processor. 
     SUMMARY 
     Embodiments herein provide a paper shredder controller, including a power supply circuit, coupled to a door open switch circuit, to an automatic forward control circuit, to an automatic reverse control circuit, and to a wastebin full circuit, in which the controller is an all-analog controller and lacks a programmable digital integrated circuit. In some embodiments, the paper shredder controller includes an overload circuit coupled to the power supply circuit. In yet other embodiments, the controller includes a forward-reverse control and relays circuit, coupled to the power supply circuit. Still in other embodiments, the controller includes a forward-reverse model delay setting circuit, coupled to the power supply circuit. In yet other embodiments, the controller includes an overheating protection circuit, coupled to the power supply circuit. Embodiments further include a POWER indicator light, coupled to the power supply circuit, and indicative of the power supply circuit being energized; a DOOR OPEN light coupled to the door open switch circuit, and indicative of a wastebin door being open; an AUTOMATIC FORWARD light, coupled to the automatic forward control circuit, and indicative of the shredder operating in an automatic forward mode; and a WASTEBIN FULL light, coupled to the wastebin full circuit, and indicative of a wastebin being full. In still another embodiment is included an OVERHEATING light, coupled to the overheating circuit, and indicative of an overheating condition. 
     Still other embodiments include a paper shredder, having an all-analog controller that lacks a programmable digital integrated circuit coupled to a power supply circuit, the power supply circuit coupled to and the all-analog controller controlling: a door open switch circuit; an automatic forward control circuit; an automatic reverse control circuit; a wastebin full circuit; an overload circuit; a forward-reverse control and relays circuit; a forward-reverse model delay setting circuit; and a motor overheating protection circuit. 
     Embodiments further include a POWER indicator light, coupled to the power supply circuit, and indicative of the power supply circuit being energized; a DOOR OPEN light coupled to the door open switch circuit, and indicative of a wastebin door being open; an AUTOMATIC FORWARD light, coupled to the automatic forward control circuit, and indicative of the shredder operating in an automatic forward mode; a WASTEBIN FULL light, coupled to the wastebin full circuit, and indicative of a wastebin being full; and a MOTOR OVERHEATING light, coupled to the motor overheating circuit, and indicative of a motor overheating condition. In yet additional embodiments, a paper shredder includes an all-analog controller that lacks a programmable digital integrated circuit. Other embodiments include a paper shredder with a housing, a motor within the housing, counter-rotating shredder blades coupled to the motor and covered by the housing, a wastebin coupled to the housing and disposed beneath the shredder blades, and an all-analog shredder controller board, coupled to the housing, and configured to operate the paper shredder in an automatic forward direction and an automatic reverse direction. 
    
    
     
       BRIEF DESCRIPTIONS OF THE DRAWINGS 
       Embodiments of the present invention disclosed herein are illustrated by way of example, and are not limited by the accompanying figures, in which like references indicate similar elements, and in which: 
         FIG. 1  depicts an example of a paper shredder, in accordance with the teachings of the present invention; 
         FIG. 2  is a cut-away side view of the paper shredder of  FIG. 1 , in accordance with the teachings of the present invention; 
         FIG. 3  illustrates a floor plan pertaining to the main controller circuit schematic of  FIG. 4 , in accordance with the teachings of the present invention; and 
         FIG. 4  illustrates the main controller circuit schematic, in accordance with the teachings of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
     The present invention can reduce the cost of a paper shredder controller using an all-analog controller design, which eliminates the need for a programmable digital IC processor. Such a design can reduce the cost of a paper shredder by up to 60%. Typically, the IC processor is used to, among other things, provide an automatic reverse function, in which the shredder motor and blades automatically revers upon the paper inlet throat becoming overloaded, or overfull. This can happen when a user attempts to feed into the shredder more pages than the shredder is rated. The all-analog controller can be used with an AC motor or a DC motor. 
       FIG. 1 , in general, illustrates paper shredder  100  that could be used without a programmable digital IC processor (all-analog, or “chipless”) in a paper shredder controller (internal, not shown), as described by the embodiments herein. Such chipless controllers would be all analog by comparison. An example of such a shredder can be shredder  100 . Shredder  100  can include shredder cover  102 , shredder head  106 , shredder control and indicator light panel  106 , feed slot  108 , wastebin with wastebin door  110 , and wastebin  112 . Feed slot  108  can be disposed above shredder blades, which turn paper input into feed slot  108  into waste “shreddant,” after which shreddant is directed into wastebin  112 . 
       FIG. 2  is a side view illustration of the structures, some of which may be internal to shredder  100 . Shredder  100  may include shredder motor  225 , which can turn shredder blades  235 , when activated. Shredder blades  235  can include at least a pair of counter-rotating blades interposed with close tolerances. When paper is placed in feed slot  120 , sensor  215  can detect its presence, causing shredder motor  225  to turn on. The inserted paper is comminuted into shreddant (waste material). Shreddant falls into and can accumulate within wastebin  112  until paper full sensor  240  detects a high level limit of shreddant, causing shredder motor  225  to turn off until the shreddant is removed. When wastebin door  110  is opened to remove accumulated shreddant, wastebin door status sensor  245  detects the operation. Wastebin door status sensor  245  is shown as a pin-and-throw switch-type of door open/closed sensor coupled with a single throw, double pole switch  230 , although other types of sensors, including electronic and electromechanical, are contemplated. Once shreddant has been cleared from wastebin  112 , and wastebin door  110  is closed, shredder motor  225  enters standby mode awaiting insertion of paper into feed slot  120 . 
     Circuit schematic floorplan layout  300  of  FIG. 3  describes the relative position of certain embodiments of operative circuits, which could be used in a chipless paper shredder controller  300 . The following also refers to  FIG. 4 , an embodiment of chipless paper shredder controller schematic which can include power supply circuit  310 , door open switch circuit  315 , overload circuit  320 , automatic forward control circuit  325 , automatic reverse control circuit  330 , paper full circuit  335 , wastebin full circuit  340 , frame relay switch circuit including reversing switch (forward-reverse control and relays circuit)  345 , forward-reverse model delay setting circuit  350 , and overheating protection circuit  355 . 
     Power supply circuit  310  uses the RC Buck principle: power line L passes power through discharge resistors R 1 , R 2 , and parallel coupling capacitor C 3 . Power then is rectified by D 6  and D 7 , followed by Zener diode DZ 1 . Capacitors C 4 , C 5  and resistor R 21  filter power through L 3 . LED L 3  illuminates as the POWER light when the power supply circuit is energized in shredder  100 . 
     Door open switch circuit  315  is coupled to the power supply circuit  310  and can use a single throw, double pole switch, such as switch  230  in  FIG. 2 . In operation, when S 2  conducts from switch S 2  pole  1  to switch S 2  pole  2 , the wastebin door is closed, thereby allowing the shredder motor and shredder circuitry to be in standby. However, when shredder waste bin door opens, the operation circuit continuity is broken. Switch S 2  is changed to conduct from switch S 2  pole  1  to switch S 2  pole  3 , transmitting power through current-limiting resistors R 6  and R 7 , and blocking diode D 2  to LED L 1  and through resistors R 10  and R 11  to neutral (N). The latter circuit configuration illuminates LED L 1  to indicate that the wastebin door is open. Further, the motor turns off, and the shredder circuitry stops functioning. 
     Overload circuit  320  can include current sampling resistor R 11 , rectifier diode D 4 , the current limiting resistor R 15 , filter capacitor C 2 , and optocoupler U 2 . When the current increases through R 15 , optocoupler U 2  is turned on. When optocoupler U 2  turns on, VCC is passed through divider subcircuit R 16  and R 29  and coupled to non-inverting input (pin  3 ) of the comparator U 1 A. Non-inverting input (pin  3 ) of comparator U 1 A also is coupled to delay capacitor C 7 . Optocoupler U 2  also is source for the comparator U 1 A inverting input (pin  2 ), which is coupled to the inverting input by way of dividing resistors R 17 , R 31 . When the non-inverting input (pin  3 ) voltage is higher than inverting input (pin  2 ), comparator U 1 A output (pin  1 ) assumes a high value, which is fedback through resistor R 18 , locking in the overload signal, and causing lamp L 4  to illuminate indicative of an OVERLOAD condition. The motor shuts off. 
     Automatic reverse control circuit  325  can include resistors R 20 , R 22 , R 26 , R 33 , R 35 , R 36 , capacitors C 9  and C 10 , transistors Q 7  and Q 3 , diodes D 9 , D 10 , and D 11 , and relay elements RELY 1 A and RELY 2 A. Automatic reverse circuit activates in an overload condition, in an attempt to clear an excess of paper from the paper feed slot. When the overload circuit  320  resistor R 18  output reaches a high level, the HIGH signal traverses R 22 , D 9 , and R 26 , turning on Q 7 . When Q 7  is ON, RELY 1  and RELY 2  OPEN in response to relay elements RELY 1 A and RELY 2 A, respectively, which causes the motor to automatically operate in the reverse direction. In addition, the HIGH signal from R 18  also traverses R 20 , R 33 , and delay capacitor C 9 . When C 9  is fully charged, Q 3  is turned ON, causing Q 7  to turn OFF. When Q 7  turns OFF, RELY 1  and RELY 2  are caused to CLOSE, stopping the automatic reverse operation. The time for automatic reverse operation is a predetermined period established, in part, by the value of capacitor C 9 . 
     Automatic forward control circuit  330  operates when paper is detected at the feed opening. When paper is at the opening of the feed slot, the illumination of IR 1  by IT 1  is blocked, which sends the non-inverting pin (pin  10 ) of op-amp U 1 C to a value that is higher than the inverting input (pin  9 ). As a result, the comparator U 1 C output (pin  8 ) goes HIGH, which signal propagates through diode D 18 , and resistors R 39  and R 32 , to the base of transistor Q 2 . As a result, Q 2  turns ON, causing RELY 3 A to turn ON, beginning the automatic forward operation. 
     Wastebin full circuit  335  can include infrared transmitter device IT 2 , infrared receiver device IR 2 , capacitor C 8 , full-wave rectifier D 16 , D 19 , with a smoothing capacitor C 13  feeding the non-inverting input (pin  12 ) of comparator op-amp U 1 D. Inverting input (pin  13 ) is supplied by way of R 34 , R 43 , and the feedback network including R 44 , switch Q 6 , and resistors R 45  and R 46 . When shreddant accumulates to a predetermined level in the shredder wastebin, infrared transmitter IT 2  emission to infrared receiver IR 2  is blocked, which causes non-inverting input (pin  12 ) of comparator op-amp U 1 D to be charged over a preselected period by C 13 , causing U 1 D output (pin  14 ) to go HIGH. This HIGH signal is propagated back into automatic forward control circuit  330 , through R 30  to switch Q 5 . Switch Q 5  is turned ON, and this signal is transmitted to Q 2 , causing switch Q 2  to turn ON. When Q 2  turns ON, RELY 3 A is caused to turn OFF, and the motor stops working. The HIGH output from U 1 D is transmitted to LED lamp L 5 , which illuminates to indicate the WASTEBIN FULL condition. 
     Infrared emission control circuit  340  for wastebin full circuit  335  can employ infrared transmitter IT 2  and diode D 5  to protect IT 2  from excessive reverse-phase current. IT 2  can be used to detect the level of shreddant in the wastebin which, when at a predetermined level, causes IT 2  to illumination to infrared receiver device IR 2  in paper full circuit  335  to be blocked. By illuminating IR 2 , non-inverting input (pin  12 ) in comparator U 1 D is driven HIGH, causing the circuit to operate as stated above. 
     Forward-reverse control and relays circuit  345  operates the shredder relays (RELY 1 , RELY 2 , and RELY 3 ) which control the forward and reverse motion of the shredder motor and blades. In embodiments, activating RELY 1 B and RELY 2 B cause the motor to operate in the reverse direction, while activating RELY 3 B causes the motor to operate in the forward direction. Element K 1  can be a reversing toggle switch, which can provide control to operate the motor in the forward or reverse direction or to place the motor in STOP. 
     Forward-reverse model delay setting circuit  350  can include resistor R 2 - 1  connected to the base of switch Q 1 , resistive divider R 3 , R 24 , and timing capacitor C 6 , which are coupled between switch Q 1  collector and emitter. Coupled to switch Q 1  collector can be Zener diode DZ 3 . Also coupled to switch Q 1  emitter can be infrared transmitter IT 1 . The resistance of R 2 - 1  can vary with the temperature of the motor. When the motor reaches the predetermined temperature indicative of overheating, switch Q 1  turns ON. IT 1  can illuminate IR 1  in automatic forward circuit  330 , which can ultimately turn Q 2  OFF, causing RELY 3 A to turn OFF, stopping automatic forward operation. 
     Overheating circuit  355  can include thermostat (overheating switch) S 1 , diode D 1 , rectifier diode D 3 , Zener diode DZ 2 , current limiting resistors R 4 , R 5 , and R 8 , filter capacitor C 50  and LED L 2 . In normal operation, thermostat switch S 1  is CLOSED, allowing current to flow through R 4  and R 5 , diode D 1  and switch S 1 . When an overheating condition is sensed, thermostat switch S 1  OPENS, the motor turns OFF, directing current through R 4 , R 5 , R 8 , DZ 2 , rectifying diode D 3 , and through overheat indication LED L 2 . 
     The examples used herein are intended merely to facilitate an understanding of ways in which the invention may be practiced and to further enable those of skill in the art to practice the embodiments of the invention. Accordingly, the examples and embodiments herein should not be construed as limiting the scope of the invention, which is defined solely by the appended claims and applicable law. Moreover, it is noted that like reference numerals represent similar parts throughout the several views of the drawings, although not every figure may repeat each and every feature that has been shown in another figure in order to not obscure certain features or overwhelm the figure with repetitive indicia. It is understood that the invention is not limited to the specific methodology, devices, apparatuses, materials, applications, etc., described herein, as these may vary. It is also to be understood that the terminology used herein is used for the purpose of describing particular embodiments only, and is not intended to limit the scope of the invention.