Abstract:
A coin escrow device has a coin jam detection mechanism that uses a magnetic switch. Magnets are connected to supports which move close to and away from the magnetic switch as a result of a coin deposit and the movement of the escrow device&#39;s gates. When a coin jam occurs, the magnets are positioned such that the magnetic switch is on.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention generally relates to coin operated systems and, more particularly, to coin escrow devices for using coin operated systems such as vending machines, coin operated telephones, and the like. 
     2. State of the Art 
     Coin operated vending systems, such as coin operated telephones, often include devices, called “escrow” devices to temporarily hold coins until such time as control signals indicate whether the coin should be returned to the system user or permanently collected. Typical escrow devices in coin operated telephones include a mechanism to release the coins to a coin box in the event that a call has been successfully placed, and a mechanism to return coins to the calling party in the event that a call is not successfully completed. 
     Escrow devices for coin operated vending systems needs to be reliable. An escrow device must operate to discharge all escrowed coins to a collection box only when the vending operation has been successfully completed and, conversely, must return all escrowed coins to the system user only when a vending operation has not been successfully completed. If an escrow device does not operate reliably, the vending system may be damaged by an irrate user, or revenue can be lost to the owner of the system. U.S. Pat. No. 4,782,937 describes a prior art escrow device for coin operated systems. This patent is incorporated herein by reference. 
     In coin operated escrow systems, jamming is a common problem. For this reason, some coin escrow devices use jam detection circuitry. In prior art systems, electro-mechanical means have been employed to detect jamming within the coin escrow hopper using contact switches. When a coin deposit is detected, a contact switch is closed to tell the control electronic module that the coin escrow has activity. When a call connection is made or fails, a gate of the escrow hopper will open to accept or return the coins, and the contact switch will be reset to an open circuit position. If the coin escrow is jammed, the contact switch will remain closed and thus give a signal to the control electronic module that there is a coin jam. The use of contact switches can cause problems, however. Contact switches are subject to breakdowns due to air corrosion, electrochemical corrosion, or for mechanical reasons. To avoid the breakdown problems common with contact switches, some escrow systems do not use coin jam detection at all. 
     It is desired to have an improved system to detect jams in a coin escrow device. 
     SUMMARY OF THE INVENTION 
     Generally speaking, the present invention provides a coin escrow device using a magnetic switch in a jam detection mechanism. The magnetic switch can be enclosed, and thus there is no open connector which can be susceptible to corrosion or other failures common with contact switches. An example of a magnetic switch that can be used with the present invention is a reed switch. Magnets are moved close to and away from magnetic switch in a manner to indicate coin jams. 
     In one embodiment, a magnet on a support is moved from a normal position away from the magnetic switch to a position closer to the magnetic switch when a gate of the coin escrow device opens. An extension connected to the solenoid pushes-up on the support when the gate of the escrow device opens. The support drops down to its normal rest position when the gate closes. When the magnet comes close to the magnetic switch, the magnetic switch turns on and thus a signal is received by the controller. If a coin jams one of the gates open, the magnet will remain near the magnetic switch, keeping it on. Thus, the controller is notified of the coin jam. 
     Another support with another magnet can be moved down from its normal position away from the magnetic switch to a position near the magnetic switch by the coin trigger which indicates the receipt of a coin by the escrow device. When a gate of the escrow device is opened, the another support is moved up to its normal position. This is preferably done at the same time that the first support and first magnet are moved toward the magnetic switch. A jam can occur such that the coin is trapped in the region of the coin trigger. The coin trigger will prevent the support from returning to its normal position. This jam will be detected because the magnets will be positioned such that the magnetic switch is on. 
     In a preferred embodiment of the present invention, the first and second magnet and supports are used together to detect both types of coin jams. Alternatively, the system could use a single magnet to detect a single type of jam. 
     In one embodiment, the supports are connected at a pivot. The magnets are positioned at a tip of the supports so that they can swing out close to and away from the magnetic switch. 
     In one embodiment, a ferrous metal plate is placed near the normal position of the first magnet. This metal plate reduces the magnetic field of the first magnet in the direction of the magnetic switch when the first magnet is in its normal position. This can be important because the magnets and magnetic switches are typically produced to be within a relatively wide tolerance range. 
     In another embodiment, when the first and second magnets are near each other in an up position, the magnetic field is expanded in the direction towards the magnetic switch. This helps keep the magnetic switch on when the two magnets are in the up position. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     The present invention may be further understood from the following description in conjunction with the appended drawing. In the drawing: 
     FIG. 1A is a diagram illustrating a front view of the coin escrow device of the present invention. 
     FIG. 1B is a diagram illustrating a side view of the coin escrow device of FIG. 1A with the magnets in their normal positions. 
     FIG. 2 is a diagram of a side view of the coin escrow device of FIG. 1, showing a coin positioned at the coin trigger causing the second magnet to move closer to the magnetic switch. 
     FIG. 3 is a diagram of the side view of the coin escrow device of FIGS. 1 and 2 with the axle of the solenoid pushing the first and second magnets upward when one of gates is opened. 
     FIG. 4A is a top view of a support for one of the magnets used with the present invention. 
     FIG. 4B is a front view of the support of FIG.  4 A. 
     FIG. 4C is a side view of the support of FIG.  4 A. 
     FIG. 5A is a top view of another support or another magnet of the present invention. 
     FIG. 5B is a front view of the support of FIG.  5 A. 
     FIG. 5C is a side view of the support of FIG.  5 A. 
     FIG. 6 is a perspective view of the coin escrow device of the present invention. 
     FIGS. 7A-7D are diagrams illustrating the positions of the magnets with respect to the magnetic switch. 
     FIGS. 8A and 8B are diagrams illustrating the effect of a metal plate when the bottom magnet is in its normal position. 
     FIGS. 9A and 9B are diagrams that illustrate the expansion of the magnetic field when the magnets are close to each other. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 is a diagram illustrating a front view of the coin escrow device of the present invention. Coin escrow device  20  includes a housing  22  used for containing the coins. Housing  22  includes a coin acceptance path  22   a , and a coin return path  22   b . When the left coin gate  24  opens, the coins in the escrow device are sent to the coin acceptance path  22   a . When the right gate  26  opens, the coins are sent to the coin return path  22   b . The gates  24  and  26  are opened and closed by the solenoids  28  and  30 . Solenoid  28  causes plunger  32  to move up, opening the gate  24 . Solenoid  30  causes plunger  34  to move up, opening the gate  26 . When the solenoids are turned off, the plungers return to their rest positions, closing the gates  24  and  26 . The plungers  32  and  34  have extension bars, or axles,  36  and  38  which are used for moving the magnets and the magnet supports. 
     The first magnet  40  is positioned in a first support  42 . In a preferred embodiment, the first support  42  is sometimes called the small arm and second support  44  is sometimes called the flag. Second support  44  holds the second magnet  46 . The second support  44  has a portion  44 A which is contacted by the coin triggers to knock down the second support  44  when a coin is received. FIG. 1A is shown without the circuit board containing the magnetic switch. 
     FIG. 1B is a diagram illustrating the side view of the coin escrow device of FIG.  1 A. In the normal rest position, the magnet  40  is adjacent to the ferrous metal plate  48 . The ferrous metal plate  48  is preferably connected through a metal screw to the metal casings of the solenoids. As is described in FIGS. 8A and 8B, the effect of the metal plate  48  is to reduce the magnetic field in the direction of the magnetic switch  50 . The magnetic switch  50  is shown here with its magnetic switch control range  50   a  shown in phantom. The magnetic switch  50  is preferably a reed control switch. A reed control switch is an enclosed unit having two leads, one of the leads contacting the other in the presence of a high enough magnetic field. 
     In the normal position, the support  44  tilts away from the magnetic switch  50 . The magnetic switch  50  is on the circuit board  54 . Note that in FIG. 1B, in the normal position of the first and second supports  42  and  44 , both the magnets  40  and  46  are out of the control range  50   a  of the switch  50  and thus the magnetic switch is off. 
     FIG. 2 is a diagram of the side view of the coin escrow device of FIG. 1 with the second support moved from its normal position to a position within the switch control range  50   a  of the magnetic switch  50 . Coin  56  drops down the coin entrance  58 , contacts the arm of the coin trigger  52 , and rotates the coin trigger  52 . Projection  52   b  of the coin trigger  52  pushes on the region  44   a  of the support  44 . This causes the magnet  46  to drop within the control range  50   a  of the switch  50 . In a preferred embodiment, the support  44  is kept tilted at an angle towards the switch  50  by the support  42 . 
     FIG. 3 is a diagram illustrating the side view of the coin escrow device of FIGS. 1 and 2, where an extension  60  connected to the plunger  34  on the solenoid  30  pushes up the first support  42  and second support  44 . When the plunger goes up, the gate associated with that plunger also opens up. In this position, the magnets  40  and  46  combine in their strengths to produce a strong enough magnetic field at the magnetic switch  50  to turn it on. A description of this effect is described below with respect to FIG.  9 . When the gate is closed, the extension  60  lowers, and support  42  drops down to its normal position. The support  44  remains tiled away from the magnetic switch  50 . 
     FIGS. 4A-4C show an embodiment of the second support  44  for the second magnet  46 . Region  44   a  is positioned so that the coin trigger can knock down the support  44  and magnet  46 . The support  44  has a sleeve  44   b  surrounding the magnet  46 . The support  44  also has a shaft portion  44   c  onto which the support  42  can be attached. The ends  44   d  are adapted to be rotated in a pivot. 
     FIGS. 5A-5C shows the first support  42  with first magnet  40 . The first support  42  includes sleeves  42   a  that surround the shaft  44   c  on the support  44 . Thus, in a preferred embodiment, support  44  rotates in the pivot, and support  42  rotates about the shaft of support  44 . 
     FIG. 6 is a diagram illustrating a perspective view of the coin escrow device  20 . 
     FIGS. 7A-7D are diagrams illustrating the operation of the magnetic switch. In unjammed operation, FIG. 7A shows magnets  40  and  46  in the normal position. The support  44  is tilted away from the magnet switch  50 . The magnet  40  is resting adjacent to the ferrous metal plate  48 . When a coin is detected, a portion of the coin trigger  52   b  pushes on the support  44  which falls down to the position shown in FIG.  7 B. In this position, magnet  46  is near switch  50 , and switch  50  turns on. When the solenoid causes a gate to be opened, an extension  60  connected to the plunger moves upward, pushing up both the supports  42  and  44 . In the position of FIG. 7C, the switch  50  remains on. When the gate closes, extension  60  drops down as shown in FIG.  7 D. In FIG. 7D, the magnetic switch  50  is off because magnets  40  and  46  are sufficiently away from the magnetic switch  50 . 
     The system of the present invention can detect coin jams. For example, if a coin jams one of the gates open, the extension  60  will hold up supports  42  and  44  as shown in FIG.  7 C. Since the controller has already sent the signal to control the gate to shut, when the controller receives the signal from the magnetic switch  50  that the switch remains on, it knows that there is a jam in the system. When the control board detects the signal, it will send a command making the solenoids respond with a movement. The movement can put the coin return and the escrow back to normal. If the coin jam is not removed, the phone will stop working and wait to be repaired. 
     When a coin jams at the coin trigger switch, region  52   b  of the coin trigger  52  will remain extended. Even when the gate tries to open and extension  60  attempts to rise, the magnets  40  and  46  will remain adjacent to the switch  50 , leaving the magnet switch in the on state. When the control board detects the signal, as described above, it will send a command to the solenoids to respond with a movement. If this does not fix the coin jam, the system is shut down for examination. 
     FIGS. 8 and 9 illustrate the magnetic deformation effect used with the present invention. There are typically large tolerances in the operating forces required to switch the magnetic switch and the magnetic densities of the magnetic bars. These variables are very difficult to control during production. For this reason, the magnetic switch  50  cannot use a very precise control system. The present invention uses the principle of magnetic deformation to avoid this problem. FIG. 7A shows a magnet  40 . When the magnet  40  is far away from the ferrous metal plate  48 , and the housing of the solenoid, the magnetic field will extend to distance H at a given strength. When the magnet  40  becomes closer to the ferrous metal plate  48 , the plate and housing of the solenoid acts as a magnetizer. The magnetic field will extend further into the magnetizer, but will shrink from a distance H to a distance H′ in the direction away from the magnetizer. In this way, the precision of the control magnetic switch can be improved, because in the normal rest position, the magnetic field of the magnet  40  in the direction towards the magnetic switch is reduced as a result of the magnetizer comprising the metal plate  48  and the metal housing of the solenoids. This situation corresponds to that shown in FIGS. 7A and 7D. 
     FIGS. 9A and 9B illustrate the effect of the magnetic deformation when the two magnets  40  and  46  are moved closer to one another. In FIG. 9A, magnets  40  and  46  are a distance X apart from each other. The magnetic field of a given strength extends a distance C away from magnet  40 . As shown in FIG. 9, as the magnets  40  and  46  come closer together to a distance of X′, smaller than X, the distance of the magnetic field of a given strength expands from C to C′. This fact is exploited in the embodiment shown in FIG. 7C, in which the two magnets  40  and  46  combine to produce a greater magnetic field in the direction of the magnetic switch  50 . 
     It will be appreciated by those of ordinary skill in the art that the invention can be embodied in other specific forms without departing from the spirit or central character thereof. For example, although the present invention describes pivotally rotated support members for the magnets, the system could be set up so that the magnets move towards and away from the magnetic switch by another means. 
     The presently disclosed embodiments are therefore considered in all respects to be illustrative and not restrictive. The scope of the invention is indicated only by the appended claims, rather than the foregoing description, and all changes which come within the meaning and range or the equivalence thereof are intended to be embraced therein.