Abstract:
The disclosure pertains to a scratch effect controller for use by a disk jockey, wherein at least one electromagnet creates the slippage tension or friction effect between the user manipulated disc, which includes a vinyl-like surface thereby simulating a vinyl record, and the rotatable or fixed platter. The strength of the electromagnet is variable so as to create a variable slippage tension or friction effect.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention pertains to a device for use by a disk jockey, wherein electromagnets create the variable slippage tension or friction effect between the user manipulated vinyl-like surface (simulating a vinyl record) and the platter, which may be rotatable or fixed. 
     2. Description of the Prior Art 
     Disk jockeys (DJs) traditionally entertain their audiences by manipulating the speed and direction of a vinyl record used on phonographic turntables to produce various effects including the well known “scratch effect”. The turntable has been replaced by CD players that have jog wheels in the form of a turntable like platters that can be turned by the DJ to produce the scratch effect and simulate other characteristics of manipulating a vinyl record on a traditional phonographic turntable. 
     An improvement on this is to rotate the platter by means of a motor and to provide a separate vinyl-like surface that the user manipulates. Between the motorized platter and vinyl-like surface is a slip disc made of plastic or felt. As the DJ moves the vinyl record-like surface, the slip disc allows the user to move the record independently of the rotating platter. U.S. Pat. No. 6,985,418 entitled “Optical Disk Reproducing Apparatus” to Hori teaches a device that includes an optical disc player, a user manipulated surface and driven rotating surface where there is some type of encoding mechanism to detect the speed and direction of both the user surface and the rotating surface. 
     The next evolution beyond the moving platter CD player for DJs is the moving platter computer interface control surface. Many DJs desire to use a phonographic turntable-like control surface to manipulate music on their computer. U.S. Pat. No. 6,541,690 entitled “Scratch Effect Controller” to Segers, for example, teaches such a device that manipulates an audio stream on a personal computer using a device that includes a rotating platter, a user manipulated surface (encoder disc), and a slip disc. 
     One problem with this combination of motorized platter and vinyl-like surface is cost. It is desirable to have a CD player with some of the characteristics of the vinyl-like surface and motorized platter without the platter being motorized. 
     Another problem not addressed by any of the prior art is the fact that each user may have a different preference as to the feel of the slippage between the vinyl-like record and the rotating platter. On a traditional phonographic turntable, the user may choose from different various slip discs made from a variety of different materials. This does not always produce the most desirable results. All of the above motorized and non-motorized CD players and DJ control surfaces have a similar limitation. 
     OBJECTS AND SUMMARY OF THE INVENTION 
     It is therefore an object of the present invention to provide a device for a disk jockey to create audio effects with a CD player, such as a scratch effect controller, wherein the slippage between the user manipulated surface and the rotatable or fixed platter is varied by a variable slippage control. 
     These and other objects are attained by providing a scratch effect controller with electromagnets to create the variable slippage tension between the user manipulated surface and the rotatable or fixed platter. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further objects and advantages of the invention will become apparent from the following description and from the accompanying drawings, wherein: 
         FIG. 1  is a partially exploded schematic of a CD player with a user manipulated surface and a rotating platter, such as is taught in the prior art. 
         FIG. 2  is a partially exploded perspective view of the scratch controller of the present invention. 
         FIG. 3  is a possible embodiment of the encoding pattern on the upper surface of the user manipulated disc. 
         FIG. 4  is a schematic of the control section of the electromagnets of the present invention. 
         FIG. 5  is an exploded perspective view of an alternative embodiment of the scratch controller of the present invention including a fixed platter. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the drawings in detail wherein like numerals indicate like elements throughout the several views, one sees that  FIG. 1  discloses a typical scratch effect controller  100  of the prior art wherein a user manipulated disc  102  includes an upper surface  103  which simulates a vinyl record. User manipulated disc  102  is mounted on a motor-driven rotating platter  104  with a slip disc or resin sheet  106  therebetween. The slip disc or resin sheet  106  provides for reduced friction between the user manipulated surface  102  and the motor-driven rotating platter  104 . Motor  108  drives shaft  110  in concert therewith which drives motor-driven rotating platter  104 . Shaft  110  further extends upwardly from motor-driven rotating platter  104  thereby providing an axis to pass through the central apertures (not shown) of user manipulated surface  102  and slip disc or resin sheet  106 . A sensor (not shown) detects the movements of user manipulated surface  102 . 
     The scratch controller  10  of the present invention is illustrated in  FIG. 2 . Rotating platter  12  is mounted on shaft  14  and typically moves in concert therewith. Shaft  14  may be driven by optional motor  16  or journaled for free rotation. User manipulated disc  18  is supported by and coaxial with rotating platter  12  (rotating platter  12  may have an upwardly extending spindle, not shown, much like a conventional turntable, to receive the central aperture  22  of user manipulated disc  18  shown in  FIG. 3 ). User manipulated disc  18  is made of magnetic material, such as steel, or contains magnetic material, such as pressed vinyl permeated with small particles of magnetic material. Alternately, the surface could be made from injection molded plastic permeated with small particles of ferrous material during the molding process. Typically, the lower surface  19  of user manipulated disc is coated with a low friction material, such as Teflon (polytetrafluoroethylene). The rotating platter  12  typically has substantial rotational inertia so that when optional motor  16  is omitted or is turned off the user can manually initiate rotational motion of rotating platter  12  and subsequently vary the rotational speed of user manipulated disc  18  so as to be different from that of rotating platter  12 . 
     User manipulated disc  18  has an upper surface  20  which simulates the feel of a vinyl record. Upper surface  20  further typically includes a central aperture  22  (see  FIG. 3 ). Upper surface  20  further includes encoding pattern  24 , such as is shown in  FIG. 3 . The typical encoding pattern shown in  FIG. 3  is that disclosed in U.S. Pat. No. 6,541,690 entitled “Scratch Effect Controller” issued on Apr. 1, 2003 to Segers, the entire contents of which are hereby incorporated by reference. Those skilled in the art will recognize a broad range of equivalents after review of the present disclosure. 
     Optical pick up  26  reads the rotating encoding pattern  24  of upper surface  20  of user manipulated disc  18  and transmits the data to a digital system such as that disclosed in the above-identified U.S. Pat. No. 6,541,690 thereby controlling the playback of digitally encoded music in response to the movements of the user manipulated disc  18 . The scratch effect may be proportional to the difference between the rotational velocity and a reference rotational velocity (such as that corresponding to 33⅓rpm) or, particularly in the case of the rotating platter  12  not being driven by motor  16 , the rotational acceleration of user manipulated disc  18  (deceleration being negative acceleration). 
     Electromagnets  30  are mounted in a stationary position below rotating platter  12  for increasing a force between the user manipulated disc  18  (which is attracted to the electromagnets) and the rotating platter  12 . The strength of electromagnets  30  is adjustable to vary the friction between rotating platter  12  and user manipulated disc  18 . The circuitry for adjusting the strength of electromagnets  30  is illustrated in  FIG. 4 . 
     As shown in  FIG. 4 , detector  32  senses when the DJ or other user touches the user manipulated disc  18 . Detector  32  typically could be a tact switch, capacitive detection, reed switch or some other means of touch sensing known to those skilled in the art of electronic design. Detector  32  connects to a microprocessor or microcontroller  34  either directly or through analog or digital circuitry depending on the type of detector. In this disclosed embodiment, tact switch  32  is connected to directly to an input port  36  of microcontroller  34 . Microcontroller  34  detects the switch closure, which represents the user touching the surface of the user manipulated disc  18 . 
     Microcontroller acts upon the detection of the switch closure by sending a predetermined signal via an internal digital to analog converter or PWM circuit to the circuit that drives electromagnets  30 . This driving circuit may be either an operational amplifier (illustrated as element  38 , or transistor circuit, or any other means known to someone familiar with the art, capable of producing sufficient current to produce a strong enough magnetic field in the electromagnets  30  to create the effect of friction, or slippage tension, between the user manipulated disc  18  and rotating platter  12 . 
     The friction can be adjusted by a user manipulated control such as a potentiometer, a switch, or series of switches. In the illustrated embodiment of  FIG. 4 , the user manipulated control is a potentiometer  40  which is connected to a port  42  of the microcontroller  34  which contains an analog to digital converter. The analog to digital converter creates a digital signal that corresponds to the position of the potentiometer  40  (i.e. the voltage on the output of the potentiometer). Microcontroller  34  uses this information to send out a predetermined signal to electromagnets  30  when the user manipulated disc  18  is touched (in this case, the tact switch  32  is closed). 
       FIG. 5  is an exploded schematic of an alternative embodiment of the scratch controller  10 ′ of the present invention. Scratch controller  10 ′ includes a base  200  much like a conventional turntable. Platter  202  is fixed into place by screws  204  (or similar attachment devices or methods) on base  200  and does not rotate. Platter  204  includes central chamber  206  about the center thereof. User manipulated disc  208  rotates within platter  204  about an axis  209  and includes lower structural disc  210  and upper vinyl-like surface  212  glued thereto. The lower surface of user manipulated disc  208  may include polytetrafluoroethylene or a similar low friction material. Encoding disc  214  with encoding pattern is fixed to the underside of lower structural disc  210  and fits within central chamber  206  of fixed platter  204 . Optical pick up  216  is secured to fixed platter  204  and measures the rotational velocity (from which rotational acceleration can be derived). Electromagnets (not shown) can be embedded in fixed platter  204  or inserted fixed underneath fixed platter  204  in order to perform the function of electromagnets  30  in  FIG. 2 . The electromagnets in this embodiment are driven by the circuit illustrated in  FIG. 4  and described herein. 
     Thus the several aforementioned objects and advantages are most effectively attained. Although preferred embodiments of the invention have been disclosed and described in detail herein, it should be understood that this invention is in no sense limited thereby and its scope is to be determined by that of the appended claims.