Abstract:
The invention is directed to a touch-sensitive paper shredder control system. The touching feature is implemented through a series of electronic circuits, taking input from a conductive touch panel on the shredder feed throat, processing the signal, and through a motor driving circuit, stopping the mechanical parts of the shredder. The system has a touch detection circuit unit, which contains a bioelectricity controlled switching circuit to sense the conductive touch panel. The bioelectricity controlled switching circuit is configured to trigger a ground switching circuit in the touch detection circuit unit which outputs to a multifunction control circuit unit. The control circuit unit then takes care of the remaining protection issues. The touching device for paper shredders protects humans and other living beings including pets from injuries through automatic and real time monitoring. The complete control process is both safe and sensitive.

Description:
CROSS-REFERENCE TO RELATED PATENTS AND APPLICATIONS 
       [0001]    This U.S. Patent Application claims priority to, and is a Continuation of, co-pending U.S. patent application Ser. No. 12/841,992, entitled “Paper Shredder Control System Responsive to Touch Sensitive Element” filed Jul. 22, 2010, which is a continuation-in-part of co-pending U.S. patent application Ser. No. 12/576,493, entitled “Touch-Sensitive Paper Shredder Control System,” filed on Oct. 9, 2009, which is a Continuation of U.S. Pat. No. 7,622,831, entitled “Touch-Sensitive Paper Shredder Control System,” filed on Jul. 12, 2007 and issued on Nov. 24, 2009, which is a Continuation-in-Part of U.S. Pat. No. 7,471,017, which Patent being filed on Aug. 30, 2006 and issued on Dec. 30, 2008, with each Application and Patents being of the same inventor hereof, and each being assigned to the same Assignee hereof, and with each Application and Patents being respectively incorporated by reference in their entirety. 
     
    
     FIELD OF THE INVENTION 
       [0002]    This invention is related to office equipment and the safe control of paper shredders, in particular touch-sensitive paper shredder control systems, responsive to a touch of a shredder blade. 
       BACKGROUND OF THE INVENTION 
       [0003]    Automated office appliances have proliferated in modern life and workspaces, and one of the most common appliances are paper shredders. Currently, paper shredders have entered into homes, some of them with automatic sensors. The sensors may be configured to detect objects inserted therein and signal the paper shredder to begin to work by grabbing the object and shredding them. Unless the paper shredder is turned off, the shredder may always be in stand-by mode. However, because paper shredders are destructive devices, if human users are not careful when using them, an injury may occur. Many current paper shredders do not have protective devices to prevent objects or body parts from entering into the throat of the shredder—potentially bringing a safety hazard into the office or home. 
         [0004]    Among the present day paper shredders, there have been shredders using the technology of contact detection to stop the shredder&#39;s blades from injuring a person or pet. Referring to  FIG. 1 , the circuit shown therein is an example of this technology. SW 2  is a polarity conversion switch and it can exchange the hot lead and ground lead of the AC power. Resistors R 12  and R 13 , capacitors C 3  and C 2 , and diodes D 11 , D 12 , D 13 , D 14 , D 15  and D 6  comprise a 24V power supply for the relay. Diode D 6 , D 7 , and capacitor C 1  comprise a power supply for U 1 , the voltage detection integrated circuit. The positive terminal of the power supply is the hot line of the AC power. Relay switch RLY- 1 , diode D 2 , transistor Q 1 , resistors R 5 , R 27 , and R 6 , and optical coupler U 5  comprise a power supply for the equipment. Diodes D 1 , D 8  and D 21 , thermal control lamp (orange), transistor Q 4 , resistors R 4 , R 14 , and R 11 , and motor thermal control switch comprise a thermal control indication circuit. Fuse F 1 , switch RLY 1 , motor, function switch, and motor thermal control switch comprise a motor operation circuit. The rotation direction is determined by the function switch setting. Power supply, resistors R 7 , R 1 , R 9 , R 2 , R 8  and R 10 , diodes D 20 , D 16 , D 4 , D 5 , D 9  and D 10 , transistors Q 2  and Q 3 , and pin  5  of the voltage detection integrated circuit comprise a LED indication circuit. The metal part of the panel, resistors R 20 , R 19 , R 21  and R 22 , capacitor C 8 , and diodes D 19  and D 17  comprise a touch detection circuit. 
         [0005]    When the function switch is set at the “off” position, the machine is not working. When the function switch is set at other positions and the wastepaper basket is separated from the machine, the machine is on but not capable of cutting paper. When the basket is detached from the machine body, the spring switch is open to cut power to the motor. The operation of the circuit for the breaking of the spring is as follows: pin  1  of U 1  detects the break of the spring, pin  5  of U 1  becomes “high”, Q 3  and Q 2  cutoff and the motor doesn&#39;t turn. The power indicator and touch/basket detach indicator are on because these two indicators, R 7 , R 8 , D 9 , and the motor thermal control switch form a current loop. 
         [0006]    When the function switch is moved away from “off”, and the wastepaper basket is in position, the machine is ready to work. The sequence of circuit operation is as follows: pin  1  of U 1  becomes “low” and Q 3  and Q 2  become conducting. At the same time, pin  6  of U 1  becomes “low”, Q 1  is on, and the relay RLY 1  is closed. Now if the function switch is set at “on”, the machine will cut the paper if there is paper in the throat, otherwise the shredder is on standby. Under these circumstances, if hands, metal, or living animals contact the metal part at the feed throat, AC power, circuit elements (R 21 , R 19 , R 20 ,) and the contact will form a circuit, and turn off the motor because pin  8  of U 1  now is “low” and pin  5  and  6  of U 1  are “high”. To be more specific, as pin  6  of U 1  is “high”, Q 1  is off and the motor power is turned off. As pin  5  of U 1  is “high” and Q 2  and Q 3  are cut off, the touch protection indicator is on. After the contact is removed from the feed throat, the shredder returns to normal operation. 
         [0007]    The touch protection is achieved through the installment of conductive touch panel at the paper intake. When touching the conductive panel, the conductivity of human body provides a faint signal to the control circuit to activate the touch protection. In this case, two 2.2M ohm resistors largely decrease the current that flows through the human body and thus the circuit may not harm a human. By using this technique, a sensitive voltage detection integrated circuit is needed to monitor the status of the touch panel in real time. Thus the demand for a highly stable and sensitive integrated circuit is apparent. Circuit aging caused by long-term usage will also diminish or even cut the circuit&#39;s detection capability. As for the two resistors with high values, they limit the current that may flow through the human body, but they may also lose their capability in a humid environment. Moreover, a human may come in direct contact with AC power, causing electric shock or even endangering life. 
       SUMMARY OF THE INVENTION 
       [0008]    The present invention solves the above-mentioned shortcomings by providing a touch-sensitive paper shredder control system making use of bioelectricity. The control process is safe and sensitive. The circuit is stable in performance, and can be applied in a wide degree of situations. To meet the above objectives, the touching device for paper shredders is constructed as below. 
         [0009]    The touch-sensitive paper shredder control system may include a function module, power supply module, conductive touch panel, and a shredder mechanical component. The function module may include a touch detection circuit unit, motor reversal detection circuit unit, paper intake detection circuit unit, overload protection circuit unit, control circuit unit, and function switch having on, off, and reverse positions. All units in the function module may be connected directly to the control circuit unit except for the function switch, which, together with the control circuit unit, controls the motor driving circuit unit, and thus the shredder&#39;s mechanical components. 
         [0010]    The power supply module may include an AC power interface switch, safety switch, fuse, control switch, power supply of control circuit unit, and motor driving circuit unit. The AC power interface switch, safety switch, fuse, and control switch may be connected in series and, through the control of the function switch, connect to the motor driving circuit unit. The control switch is a relay switch. The AC power, which flows through the fuse, is rectified, filtered and regulated to provide DC power to all circuit units. 
         [0011]    The conductive touch panel may be connected to the touch detection circuit unit. The touch detection circuit unit consists of a bioelectricity controlled switching circuit and a ground switch circuit. The bioelectricity controlled switching circuit may be a transistor circuit with a first transistor where the touch panel is connected to the base of the first transistor via a first resistor. The base of the first transistor is also connected to ground via a parallel combination of a second resistor and a first capacitor. The emitter of the first transistor is connected to ground via a parallel combination of a third resistor and a second capacitor, and is also connected to the input of the ground switch circuit. 
         [0012]    The collector of the first transistor drives in parallel, a power indicator LED and a touch indicator LED and is then connected to the power supply. The ground switching circuit is also a transistorized switching circuit having a second transistor. The base of the second transistor is connected to the output of the bioelectricity controlled switching circuit, the emitter is grounded, and the collector is connected to the input of the control circuit unit via an optical coupler and to the power supply via a fourth resistor. 
         [0013]    The paper intake detection circuit unit is connected to the control circuit unit also. The paper intake detection circuit unit comprises a light emitting diode and a photosensitive diode. The emitting area of the former and the optics sensing part of the latter face each other and are installed on the walls of opposite sides of the feed throat. The overload protection circuit and the motor reversal detection circuit unit are connected to the control circuit unit. 
         [0014]    The touch-sensitive paper shredder control system has adopted cascaded circuits to ensure human safety when a human touches the conductive touch panel. The electricity from the human body enables the bioelectricity controlled switching circuit, and then all the connected circuits. The control circuit unit disables the mechanical part of the shredder and it ensures human safety. Even if the power switch is turned on, the mechanical part of the shredder still doesn&#39;t work. The shredder realizes real time monitoring. The complete control process is both safe and sensitive. The machine performance is stable and reliable and easy to operate without human oversight. 
         [0015]    In other embodiments of the touch-sensitive paper shredder control system, a shredder blade is configured to be sensitive to bioelectricity from a living being. When the bioelectricity is detected at the shredder blade, a control system responds by actuating a restraint to a shredder mechanical part, essentially halting a shredder blade. In yet other embodiments, the shredder motor is de-energized prior to actuating a restraint, reducing torque on driving and driven mechanical elements during deceleration of the shredder blade. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]    The invention is generally shown by way of reference to the accompanying drawings in which: 
           [0017]      FIG. 1  is a circuit diagram illustrating the electrical components of a shredder control system using prior art technology; 
           [0018]      FIG. 2  is a block diagram of the components and modules within a touch-sensitive paper shredder control system of the present invention; 
           [0019]      FIG. 3  is a circuit diagram of the electrical components of a touch-sensitive paper shredder control system of the present invention; 
           [0020]      FIG. 4  is the circuit diagram of the electrical components of another embodiment of a touch-sensitive paper shredder control system of the present invention; 
           [0021]      FIG. 5  is a flow chart of the control process used in connection with a touch-sensitive paper shredder control system of the present invention; 
           [0022]      FIG. 6  is an illustration of an embodiment of an apparatus to stop the shredder gears from turning; 
           [0023]      FIG. 7  is a flow chart illustrating the operation of an embodiment of the invention; 
           [0024]      FIG. 8  is a circuit diagram of the electrical components of an embodiment of a touch-sensitive paper shredder blade control system, in accordance with the teachings of the present invention; 
           [0025]      FIG. 9  is a circuit diagram of the electrical components of another embodiment of a touch-sensitive paper shredder blade control system, in accordance with the teachings of the present invention; 
           [0026]      FIG. 10  is a top plan view of yet another embodiment of a touch-sensitive paper shredder control system, in accordance with the teachings of the present invention; and 
           [0027]      FIG. 11  is a top plan view of still another embodiment of a touch-sensitive paper shredder control system, in accordance with the teachings of the present invention. 
       
    
    
       [0028]    Some embodiments are described in detail with reference to the related drawings. Additional embodiments, features and/or advantages will become apparent from the ensuing description or may be learned by practicing the invention. In the figures, which are not drawn to scale, like numerals refer to like features throughout the description. The following description is not to be taken in a limiting sense, but is made merely for the purpose of describing the general principles of the invention. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0029]    In one embodiment, the touch-sensitive paper shredder control system may include the following components: a function module, a power supply module, and shredder mechanical parts. Referring to  FIG. 2 , the function module consists of a touch detection circuit unit  4 , motor reversal detection circuit unit  7 , paper intake detection circuit unit  5 , overload protection circuit  6 , control circuit unit  3 , and function switch  86 . All of these units are connected directly to control circuit unit except for the function switch, which together with the control circuit unit controls the motor driving circuit unit  2 , and then the shredder mechanical part  1 . A conductive touch panel is connected to the touch detection circuit unit, which consists of a bioelectricity controlled switching circuit and a ground switching circuit. 
         [0030]    The power supply module consists of an AC power interface unit  81 , security switch  82 , fuse  83 , control switch  84 , power supply of control circuit unit  85 , and the motor driving circuit unit  2 . The control switch is a relay switch, and the security switch is a door switch. The first four of the above-mentioned units are connected in series and, through the control of function switch  86 , connected to motor driving circuit unit. The power, through the fuse, is connected to the power supply of control circuit unit, and then to the control circuit unit. 
         [0031]    Turning to  FIG. 3 , in one embodiment, the bioelectricity controlled switching circuit is mainly a switching transistor circuit. The conductive touch panel is connected to the base of switching transistor Q 4  via resistor R 5 . Transistor Q 4  has its base connected to ground through paralleled capacitor C 7  and resistor R 6 , its collector connected directly to power VCC, and its emitter connected to ground through paralleled capacitor C 8  and resistor R 16 . The emitter of Q 4  is also connected directly to the ground switching circuit. 
         [0032]    The ground switching circuit is also a switching transistor circuit. The output from the bioelectricity controlled switching circuit is connected to the input of the ground switching circuit, i.e. the emitter of transistor Q 2 . Transistor Q 2  has its emitter connected directly to ground, its collector connected to VCC through resistor R 7 , and its collector connected to the input of control circuit unit through an optical coupler U 1 . 
         [0033]    Referring to  FIG. 4 , in another embodiment a bioelectricity controlled switching circuit is based on transistor Q 3 . The touch panel is connected to the input of the bioelectricity controlled switching circuit, i.e. the base of the switching transistor Q 3  through a serial combination of resistors R 6  and R 7 . Transistor Q 3  has its base connected to ground via a parallel combination of capacitor C 3 , diode D 4 , and resistor R 8 , the collector is connected to power supply VCC through a parallel combination of power indicator and touch indicator LED 3 , and the emitter is connected directly to the input of the ground switching circuit. 
         [0034]    The ground switching circuit is also a transistor circuit. The output from the bioelectricity controlled switching circuit, i.e. the emitter of transistor Q 3 , is connected directly to the base of the switching transistor Q 2 . The emitter of transistor Q 2  is connected directly to ground, and the collector is connected to the input of the control circuit unit  3 . 
         [0035]    Referring to  FIG. 2  the paper intake detection circuit unit is connected to the control circuit unit  3 . Now turning to  FIG. 3 , the paper intake detection circuit unit consists of a light emitting diode IT 1 , and a photosensitive diode IR 1  which face each other on opposite positions on the wall of the feed throat of the shredder. Both the overload protection circuit unit  6  and the motor reverse detection circuit unit  7  are connected to the control circuit unit  3  of the touch-sensitive paper shredder. 
         [0036]    Referring back to  FIG. 2 , both the motor reversal detection unit  7  and the paper intake detection unit  5  are connected to control circuit unit  3 , then the motor driving circuit unit  2 , and then to the shredder mechanical part  1 . The motor reversal detection unit  7  detects the reversal signal, sends the electric signal to the control circuit unit  3 , then electrically controls the shredder mechanical part  1  to reverse the motor direction through motor driving circuit unit  2 . The paper intake detection circuit unit  5  detects the paper insertion at the feed throat, sends the signal to the control circuit unit, and then drives the shredder mechanical part to cut the paper through motor driving circuit unit. 
         [0037]    Referring now to  FIG. 5 , during the paper shredding process, if a human body touches the touch panel of the feed throat, the shredder will stop immediately. The touch signal is sent to touch detection circuit unit  4 , then goes to control circuit unit  3 , and stops the shredder by cutting the power to motor driving circuit unit  2 . If a human body doesn&#39;t touch the conductive touch panel, the control circuit unit will release the control to motor driving circuit unit  2  to allow the mechanical part to work independently. 
         [0038]    Referring back to  FIG. 3 , the shredder has the following features: overload protection; optics controlled shredding; shredding, shutdown, and reversed rotation functions; and automatic touch-stop. 
         [0039]    The power supply of the control circuit unit is described below. AC input power is divided, rectified, regulated, and filtered by the circuit consists of resistors R 1  and R 2 , capacitors C 1  and C 2 , diodes D 5  and D 6 , and Zener diode ZD 1 . The regulated 24 volts DC power is the power source for the control circuit unit. It&#39;s far below the safety voltage to pass through human body and will do no harm to human or animals. 
         [0040]    The power supply for the touch detection circuit unit is described below. The AC input power, going through a bridge rectifier, is regulated and filtered to provide 12 volts DC voltage. The circuits consists of diodes D 1 -D 4 , Zener diode ZD 2 , resistor R 12  and capacitor C 3 . 
         [0041]    When a human touches the metal panel, the bioelectricity from the human body goes to the base of the transistor Q 4  via a 1 MegaOhm resistor. The bioelectricity triggers transistors Q 4  and Q 2  on, cuts off transistor Q 3 , and thus cuts the motor power so that the shredder automatically stops when people touch the feed throat. 
         [0042]    Referring now to  FIG. 4 , the shredder in this embodiment has the following features: on-off LED indicator; touch protection LED indicator; overload LED indicator; AC Power indicator; optics controlled shredding; and shredding, shutdown, and reversed rotation function. 
         [0043]    The overload protection and door open LED indicating functions are implemented by the circuit consists of R 18 , R 14 , R 13 , R 11 , and R 12 , light emitting diodes LED 1  and LED 2 , diodes D 10 , D 9 , and D 6 , Zener diode ZD 2 , capacitor C 5  and silicon controlled rectifier SCR. 
         [0044]    The power supply for the control circuit unit includes a circuit consisting of resistors R 1  and R 2 , capacitors C 1  and C 2 , diodes D 1  and D 2 , Zener diode ZD 1 , and capacitor C 2 . The same regulated 24 volts DC power is used as the power source for the control circuit unit. It&#39;s far below the safety voltage to pass through a human body and will do no harm to human or animals. 
         [0045]    The touching function is described below. When human touches the metal panel, the bioelectricity from a human body goes to the base of the transistor Q 3  via resistors R 6  and R 7 . The signal triggers Q 3  and Q 2  on, turns Q 1  off, and cuts the power to the motor. The motor stops turning and people are protected. The touch detection circuit unit will be more stable if it uses an independent bridge power supply, and is isolated from the motor by an optical coupler. 
         [0046]    When a human touches the panel, the touch of human on the metal part of the panel provides a triggering signal which via base bias circuit, turns Q 3  on. The base bias circuit consists of resistors R 7 , R 6  and R 8 , diode D 4 , and capacitor C 3 . With enough forward voltage from a human Q 3  and Q 2  are both turned on. When Q 2  is on, its collector voltage drops and thus it turns on touch indicator via R 5 , turns off Q 5  via D 16 , and turns off Q 1  via D 15 . If the machine were turning reversely at this moment, Q 5  would be on. But because of the touch voltage, Q 5  is turned off and so is the motor. The other situation is when the machine is in a shredding state. In this case Q 1  would be on to turn the motor in the forward direction. But because of human touch Q 1  is turned off and motor is turned off, too. In either case, the machine is shut off to ensure the safety of human. 
         [0047]    When a human no longer touches the machine&#39;s metal plate, transistor Q 3  turns off because there is no trigger voltage and the machine returns to a normal working state. The working principle of the power on indicating circuit is as below. When the machine is in the shredding or reversal state as selected from the function switch, the power on indicator in on and when the machine is in a stopped state, the indicator is off. The indicator circuit includes an indicator lamp, resistors R 17  and R 16 , and transistor Q 4 . When the machine is in the stop state, the indicator is off because transistor Q 4  is not conducting. As for the reversal state, the emitter junction of transistor Q 4 , diode D 12 , and function switch complete a circuit and the power on indicator is on. While the machine is in the shredding state, the emitter of Q 4 , diode D 13 , and the function switch complete a circuit and the power indicator is on. 
         [0048]    Persons with small hands, in particular, toddlers, may have fingers that are capable of circumventing mechanical safety systems of a paper shredder. Accordingly, embodiments of the present invention can encompass a paper shredder safety system that is substantially activated by shredder blade contact. Unlike proximity detectors, which actuate safety measures when a target comes with a predetermined distance of a shredder housing element, a shredder blade contact safety system described here is actuated by target contact with a shredder blade. 
         [0049]    In general, when a touch-sensitive shredder blade control system is actuated by shredder blade contact, power is removed from the shredder motor. In particular, when a living being contacts the shredder blade, the bioelectric signal generated by the living being is sensed by a biosensor coupled to a shredder blade. The received bioelectric signal actuates a control circuit unit to cause a safety stop, in which at least the shredder motor is de-energized. 
         [0050]    Turning to  FIG. 6 , yet other embodiments of the invention herein are illustrated. Control circuit  35  can actuate fast-acting solenoid  27  to deploy mechanical power restraint  25 , which restrains the rotation of the shredder blades. For example, restraint  25  may be positioned proximate to a motive element of the power transmission system between motor and blades, such as the meshing gears represented at reference  55 , which gears are synchronized with the rotation of the shredder blades. 
         [0051]    When actuated and deployed, restraint  25  may engage a driving gear, a driven gear, or both. Upon contact with a shredder blade, the user bioelectric signal causes restraint  25  to be deployed between the meshing gear teeth  55  of a driving gear and a driven gear, rapidly decelerating and stopping the blades of the shredder. It is desirable that restraint  25  be constituted to absorb the residual rotational momentum force of the shredder blades, of a durable, resilient, wear-resistant, and shock absorbent material, such as, without limitation, high density polyethylene, although other material, such as a hardened natural rubber, also may be suitable. Materials for restraint  25  are preferred to be generally inexpensive and unlikely to damage meshing gear teeth  55 . Restraint  25  can be in the form of a rubber chock, which can be mounted onto a quick-acting solenoid  27  for rapid, affirmative setting of restraint  25 . The chock can be constituted of a durable, resilient, wear-resistant, and shock absorbent material, for example, a rubber material. 
         [0052]    Typically, solenoid  27  could be in the form of a push-type solenoid, actuated by control circuit  35  in response to the bioelectric signal emanating from a living being in contact with shredder blade. Prior to deployment of restraint  25 , the shredder motor can be deactivated, after which solenoid  27  can be actuated, thus interposing chock  25  between meshing gears  55  to effect a rapid, “soft stop.” A “soft stop” significantly reduces the likelihood that neither meshing gears or other mechanical power transmission system elements, nor the user contacting the shredder blade, will experience traumatic contact with the shredder blade. 
         [0053]    Other embodiments can employ a clutch as mechanical power restraint  25  to stop moving shredder. For example, the clutch can disengage a gear from a rod connected to the gear thereby causing the rod to stop turning due to the frictional forces associated with the blade interactions. Another clutch example could be a clutch between the motor and a gear box that would disengage the torque delivered by the motor. Yet another embodiment could include a circuit that reverses the current flow to the motor to a degree that counteracts the direction of movement by the motor thereby causing a type of electromagnetic braking. Such a system may produce very little, if any, reverse direction by the motor. 
         [0054]      FIG. 7  illustrates a dual-phase method  700  of operating a touch-sensitive paper shredder control system. In a first phase, paper shredder provides a first sensor response in a first sensing process. In a second phase, paper shredder provides a second sensor response in a second sensing process. In embodiments herein, a first phase can be constituted of a shredder blade sensor sensing contact with a living being by receiving bioelectricity (a “bioelectric signal”) from the living being in a manner indicating contact. A second phase can be constituted of a conductive touch panel sensing contact with a living being by receiving a bioelectric signal from the living being in a manner indicating contact. In certain embodiments, the first phase process can include coupling the bioelectric signal to the control circuit unit. In response, the control circuit unit can de-energize the paper shredder motor and deploy a restrainer into the mechanical power transmission system, bringing the shredder blades to a rapid and complete stop. Similarly, the second phase process can include coupling a bioelectric signal applied to the conductive panel to the touch panel unit which, in turn, couples a representation of the bioelectric signal to the control circuit unit. In response, the control circuit unit can de-energize the paper shredder motor, causing the shredder blades to stop. 
         [0055]    In other embodiments, a single phase can be provided by the first sensing process, in which a shredder blade sensor senses contact with a living being by receiving a bioelectric signal from the living being in a manner indicating contact. A representation of the bioelectric signal then can be coupled to the control circuit unit. In response, the control circuit unit can de-energize the paper shredder motor and deploy a restrainer into the mechanical power transmission system, bringing the shredder blades to a rapid and complete stop. 
         [0056]      FIG. 8  is a circuit diagram illustrating an example embodiment of a touch-sensitive shredder blade control circuit  800 . Although  FIG. 8  shares some functional similarities with the touch panel-related control circuit of  FIG. 3 , it will be appreciated by one skilled in the art that touch-sensitive shredder blade control circuit  800  in  FIG. 8  is distinct from the circuit of  FIG. 3 , most notably in the adaptation of touch control system  810  to be sensitive to bioelectricity received from a living being and sensed at shredder blade  820 . 
         [0057]    In response to the sensed touch of a metal shredder blade by a living being, touch control system  810  can produce a signal  825  representative of the sensed bioelectricity by activation (ON) of cascaded transistors Q 3  and Q 4 . Biosignal  825  can be coupled to Q 2  of main control circuit  850  by way of an optoelectric coupler OPTO 1 . OPTO 1  may further isolate the living being touching shredder blade  820  from the potentially lethal electric power being used to actuate motor  840 . Transistor Q 2  can operate as a switch, and when a representation of a biosignal is receved from OPTO 1 , Q 2  can be configured to turn OFF, actuating electromechanical restraint element  860 . Electromechanical restraint element  860  can include a relay coil, which can de-energize motor  840 , when Q 2  is turned OFF. In addition, electromechanical restraint element  860  may include a solenoid coupled to a mechanical power transmission restraint. 
         [0058]    In the context of  FIG. 6 , a non-limiting example of a solenoid coupled to a mechanical power transmission restraint may be solenoid  27  coupled to mechanical power transmission restraint  25 . When Q 2  is turned OFF, the solenoid can de-energize, causing mechanical power transmission restraint  25  to be driven into the mechanical power transmission elements, such as meshing gears  55 . Alternatively, another non-limiting example of a mechanical power transmission restraint may be a clutch coupled to electromechanical restraint element  860 . In yet another non-limiting alternative, mechanical power transmission restraint  25  may be implemented using a chock and a clutch, where electromechanical redundancy is elected. 
         [0059]      FIG. 9  is a circuit diagram illustrating another example embodiment of a touch-sensitive shredder blade control circuit  900 . Blade touch sensor  910  can be coupled to an integrated circuit IC 1   920 , for example, at PIN  16 . A biosignal received from blade biosensor  910  is received on PIN  16  which, in turn, deactivates or sets a LOW power signal on PIN  15 . The LOW power signal is received by NPN transistor Q 1 , which turns OFF in response to the LOW signal, causing motor  930  to be de-energized. In addition, it may be possible to configure IC 1   920  to provide a HIGH signal on PIN  14  (Motor Forward/Reverse). A HIGH signal from PIN  14  can be coupled to turn ON NPN transistor Q 2  a reverse motion in motor  930 , at least long enough to perform electrical braking of the shredder blade. In addition, transistor Q 2  and relay RLY- 2 . 3  may be elements of an electromechanical restraint element, which also may include a chock mechanical restraint, a clutch mechanical restraint, or both. 
         [0060]    In other embodiments of the present invention, a standoff biosensor having a metalized contact element can be connected to an inner portion of a shredder assembly other than a shredder blade. When a living being contacts the metalized contact, the standoff biosensor actuates a control circuit unit to cause a safety stop. A safety stop can be characterized by de-energization of the shredder motor moving in the forward (shredding). Also, in a safety stop, a restraint may be deployed to substantially immediately stop motion of the shredder blades. Further, in a safety stop the shredder motor can be momentarily energized in the reverse direction to cause electromotive braking of the shredder blade. 
         [0061]    Turning to  FIG. 10 , shredder assembly (for convenience, “shredder”)  1000  may be configured with inner housing  1010  in which shredder blade  1020  can be disposed. Inner housing  1010  of shredder  1000  can include a frame, generally at  1030 , at least partially surrounding blade  1020 . Support frame  1030  may include one or more generally horizontal support frame members, for example, member  1032  and one or more generally vertical frame members, for example member  1034 , (with “horizontal” being oriented in parallel with a longitudinal axis of shredder blade  1020 . 
         [0062]    In selected ones of the non-limiting example embodiment of shredder  1000 , at least a portion of at least one member of support frame  1010  can be metalized, forming a metalized contact element. The metalized contact element can be a portion of the metalized frame member. In certain selected embodiments, support frame  1010  can be constituted of conductive metal members, such that essentially the entire support frame can be a metalized contact. Metalized support frame  1010  can be supported on shredder lower housing  1060 . Frame  1010  can provide improved structural support for the shredder blade  1020  within shredder  1000  and, perhaps, for shredder motor  1090  and mechanical power transmission, represented by motor driver shaft  1095 . 
         [0063]    In general, the metalized contact element, such as represented by support frame member  1032  or  1034 , stands off from (i.e., is not in contact with) shredder blade and may be interposed between an inlet to the shredder blade (in an upper housing, not shown) and shredder blade  1020  itself. Typically, the metalized contact element  1032  is coupled to a transducer  1050 , which receives bioelectric signal  1052  from a living being (not shown) in contact with the metalized contact element  1032 , and which produces a representation  1054  of the bioelectric signal. Metalized contact element  1032  coupled to transducer  1050  can be described as a standoff biosensor (in combination, standoff biosensor  1051 ) and a representation  1054  of the bioelectric signal can be described as a biosignal. Standoff biosensor  1051  can be actuated to couple biosignal  1054  to control circuit unit  1055 . Standoff biosensor  1051  can be used to sense the proximate contact of a living being (not shown) relative to shredder blade  1020 , without the living being making contact with shredder blade  1020 . 
         [0064]    In response to standoff biosensor  1051  detecting proximate contact, control circuit unit  1055  can effect a safety stop, bringing shredder blades  1020  to a rapid and complete stop. During a safety stop control circuit unit  1055  de-energizes power supply  1094  of paper shredder motor  1090 , may deploy an aforementioned restraint into the mechanical power transmission system  1095 , or both. In embodiments in which reverse motor motion is permitted, control circuit unit  1055  may momentarily energize paper shredder motor  1090  in a reverse direction to cause electromotive braking, which may further and more quickly reduce inertial shredder blade motion in the forward direction. 
         [0065]    In non-limiting alternative example embodiments, also depicted in  FIG. 10 , a metalized contact element can be a segment, a strip, or a generally circumferential ring disposed in the shredder, set apart from and generally superior to the shredder blade  1020 , relative to direction of feed into the paper shredder blade  1020 . The form of the metalized contact element may be continuous or interrupted. As illustrated in  FIG. 10 , non-limiting embodiments of a metalized contact in the form of a strip may include metalized interblade spacer  1040 , which can be disposed between adjacent shedder blade elements  1042 A,  10428 . One or more of metalized interblade spacers  1040  may be coupled to transducer  1050 , such that transducer  1050  can receive bioelectric signal  1041  from metalized interblade spacer  1040 , when in contact with a living being (not shown). Typically, interblade spacer  1040  is configured with a spacer contact surface positioned in a stand off posture, relative to and apart from, adjacent shedder blade elements (for clarity, blade elements  1042 A and  1042 B). 
         [0066]    In such an embodiment, a living being coming into contact with metalized element  1040  can actuate biosensor transducer  1050  to transmit biosignal  1054  to control circuit unit  1055 . In turn, control circuit unit  1055  can perform a safety stop by de-energizing power supply  1094 , and removing power from paper shredder motor  1090 . During the safety stop, control circuit unit  1055  also may deploy an aforementioned restraint into the mechanical power transmission system  1095  bringing shredder blades  1020  to a rapid and complete stop. Where shredder motor  1090  is configured for reverse motion, control circuit unit  1055  can cause electromotive braking by energizing motor  1090  to turn in reverse direction. In some embodiments where electromotive braking is used, control circuit unit  1055  may deploy an aforementioned restraint generally concurrently with a momentary electromotive braking of sufficient duration to bringing shredder blades  1020  to a rapid and complete stop. 
         [0067]    Combinations of aforementioned safety elements would be readily apparent to a person having ordinary skill in the art in light of the present teachings. In a first non-limiting example, plural metalized members of support frame  1010  can be electrically coupled to each other as well as to transducer  1050 , so that control circuit unit  1055  may cause a safety stop in response to contact between a living being and a coupled surface of frame  1010 . In a second non-limiting example, multiple ones of metalized spacers  1040  can be electrically coupled to transducer  1050 , so that control circuit unit  1055  may cause a safety stop in response to contact between a living being and one of metalized spacers  1040 . In a third non-limiting example, plural metalized members of support frame  1010  and multiple ones of metalized spacers  1040  can be electrically coupled to transducer  1050 , so that control circuit unit  1055  may cause a safety stop in response to contact between a living being and at least one of a metalized member, a metalized spacer, or both. 
         [0068]      FIG. 11  illustrates a top view of shredder assembly  1100 , with a vantage similar to shredder  1000  in  FIG. 10 . In selected other non-limiting example embodiments according to the present invention, shredder frame (generally at  1110 ) can be coupled to blade shield  1111 ,  1112  with individual blade shield members  1111  and  1112  being set apart by a predetermined shield gap  1115 , relative to the longitudinal axis of shredder blades  1120 . Predetermined shield gap  1115  can be sized to limit access of material to be shredded to the region encompassed within shield gap  1115 . Blade shield members  1111  and  1112  can be positioned above, and set apart from shredder blades  1120 . Typically, shield gap  1115  can be disposed beneath, and longitudinally aligned with a feed opening (not shown) of shredder  1100 . Shield gap  1115  stands off sufficiently from blades  1120  to allow expected normal operation of paper shredder  1100  to proceed, but to limit access to shredder blades  1120  and their immediate, and hazardous, environs. 
         [0069]    One or both of blade shields  1111 ,  1112  may be electrically coupled to biosensor transducer  1150 , forming in combination biosensor  1151 . Blade shield  1111 ,  1112  receive bioelectric signal  1141  transmitted from a living being in contact with electrically coupled blade shield  1111 ,  1112 , and can transmit bioelectric signal  1141  to transducer  1150 . In response, transducer  1150  can generate biosignal  1130 , which can be received by control circuit unit  1155 . When a biosignal  1130  is received by control circuit unit  1155 , control circuit unit  1155  can respond by effecting a safety stop. Similar to a safety stop corresponding to shredder  1000  in  FIG. 10 , control circuit unit  1155  can respond to biosignal  1130  by de-energizing power supply  1160  and, in turn, removing power from shredder motor  1190 , bringing shredder blades  1120  to a rapid and complete stop. In some embodiments, a safety stop caused by control circuit unit  1155  also may deploy an aforementioned restraint into the mechanical power transmission system  1195 . As with shredder  1000  in  FIG. 10 , a safety stop caused by control circuit unit  1155  also may perform electromotive braking to reduce inertial movement of shredder blades  1120 . 
         [0070]    Blade shield  1111 ,  1112  can improve structural strength and integrity of shredder  1100 , and also provide enhanced product reliability, extended product service life, and reduced operational costs. Further, shield gap  1115  between blade shields  1111 ,  1112  may be adjusted in width such that the shield gap  1115  may approximately the same as a proximate, corresponding gap in a paper feed inlet opening (not shown) for shredder  1100 . Also, shield gap  1115  may be disposed approximately equal to a proximate, corresponding gap in a paper feed inlet opening (not shown) for shredder  1100 . In addition, shield gap  1115  may be disposed to be slightly narrower than proximate, corresponding gap in a paper feed inlet opening (not shown) for shredder  1100 , while not impairing material being fed into blades  1120 . In an example embodiment in which shield gap  1115  is slightly narrower than a proximate, corresponding gap in a paper feed inlet opening (not shown) for shredder  1100 , touch contact between a living being and metalized contact sensor  1111 ,  1112  of biosensor  1151  can be more likely to cause a safety stop before the living being comes into contact with shredder blades  1120 . Such an arrangement can enhance safety aspects of shredder  1100 , even in environment where living beings are prone to direct probing of shredder  1100  internal mechanisms, or are engaged in maintenance or in testing of an energized shredder  1100 . 
         [0071]    In yet other alternative embodiments, safety stop apparatus and methods described relative to shredder  1000  in  FIG. 10 , and shredder  1100  in  FIG. 11 , may be used alone or in combination. In a fourth non-limiting example, touch contact between a living being and a blade shield  1111  electrically coupled to transducer  1150 , can cause control circuit unit  1155  to perform a safety stop. Moreover, such blade shield embodiments of  FIG. 11  also may be used in conjunction with one or more of non-limiting examples described with respect to  FIG. 10 . In a fifth non-limiting example, contact between a living being and one or more of a metalized member of frame  1010  or a metalized spacer, and one or more blade shield  1111 ,  1112  which can be electrically coupled to a transducer  1050  or  1150 , causing control circuit unit  1055  or  1155  to perform a safety stop. Further, any of the foregoing non-limiting examples may be modified so that contact sensing by shredder blade  1020  or  1120 , and by one or more of metalized frame members, metalized interblade spacers, or blade shield can cause a control circuit unit such as units  1055  or  1155 , to perform a safety stop. A person having ordinary skill in the art would recognize foreseeable modifications and alternatives in light of the foregoing disclosure. 
       BENEFICIAL USES 
       [0072]    Embodiments of the present invention provide the following beneficial uses: 
         [0073]    1. Enhanced product safety for living beings, including adult and child humans, and pets. 
         [0074]    2. Improved structural support for shredder assembly elements 
         [0075]    3. Improved structural integrity of shredder  1100   
         [0076]    4. Enhanced product reliability 
         [0077]    5. Extended product service life 
         [0078]    6. Reduced product operational costs and maintenance. 
         [0079]    As detailed above, the touch-sensitive paper shredder control system has adopted cascaded circuits. On the machine feed throat there is a blade touch sensor, which is connected to bioelectricity controlled switching circuit, ground switching circuit, control circuit unit, and then shredder mechanical part, including a blade restraint. All of these circuits ensure safety when a human, or other living being, touches the touch-sensitive shredder blade. The electricity from a human body actuates the bioelectricity-controlled switching circuit, followed by all of the connected circuits. The control circuit unit disables the shredder mechanical part and it ensures human safety. Even if the power switch is turned on, the mechanical part of the shredder still won&#39;t work if a human is touching the touch-sensitive shredder blade. As with the aforementioned touch-sensitive panel, the shredder can use the touch-sensitive shredder blade to realize real time monitoring with a control process that is both safe and sensitive. The machine performance is stable and reliable. It is easy to operate without human intervention, can be applied in wide situations, and brings safety assurance. 
         [0080]    Although the present invention has been described by way of example with references to the circuit drawings, it is to be noted herein that various changes and modifications will be apparent to those skilled in the art. Therefore, unless such changes and modifications depart from the scope of the present invention, they should be construed as being included therein.