GB2052899A

GB2052899A - Detector system for movable members

Info

Publication number: GB2052899A
Application number: GB8012527A
Authority: GB
Original assignee: Associated Leisure Games Ltd
Current assignee: Associated Leisure Games Ltd
Priority date: 1979-06-30
Filing date: 1980-04-16
Publication date: 1981-01-28

Abstract

In a coded-scale position digitiser, a binary-coded multi-track pattern of electrodes on a rotatable disc is capacitively sensed using two electrodes per track on a stationary member. Use: detecting the position of reels in an amusement machine.

Description

SPECIFICATION Detector system for movable members This invention relates to a detection system for movable members and more particularly concerns a detector system for reel members in an amusement machine.

According to the present invention we provide a detector system for detecting the position of a movable member relative to a reference position said detector system comprising a first detector member associated with said movable member and movable in response to movement of said movable member and a second detector member associated with said reference position, each detector member being provided with at least one electrode and said detector members being positioned relative to one another to provide an electrical capacitance between said electrodes at one or more predetermined relative positions of said detector members whereby the position of the movable member can be detected.

Conveniently, a plurality of electrodes are provided and the electrodes are arranged in a plurality of lines corresponding to positions of the member so that the combination of electrodes in any one line corresponds to a code which can be used to identify the position of the movable member.

Thus each individual line may comprise electrode positions which correspond to a binary code.

In one form of the invention the movable member is a rotatable member and said first detector member is arranged to rotate therewith. In this case the first detector member is preferably in the form of a disc having electrodes arranged in radial lines on a flat surface thereof.

Where the electrodes are arranged in spaced linear relationship the electrodes on the second detector member will also be arranged in linear relationship. The second detector member may be provided with a plurality of electrodes corresponding to the maximum number of electrodes which can be present in any one line on the first detector member so that the presence or absence of an electrode on the first detector member can be detected for each position in the line. Each possible position of the second detector member can then be allocated electrode positions which correspond to a code identifying that position.

The second detector member may be a plate which is fixed relative to the first detector member and is provided with the capacitor electrodes on its surface. Conveniently, the electrodes form part of a printed circuit thereon.

The dielectric may be any suitable dielectric material including air but in one embodiment of the invention it comprises a plastics material such as polyethylene.

The detector system is particularly suitable for use in detecting the positions of reel mechanism in amusement machines and in this case the first member is arranged to rotate with the reel to be detected and is provided with a predetermined electrode code arranged radially for each position to be detected.

Reference is now made to the accompanying drawings, in which: Figure 1 is a perspective view of one reel member of a set of such reel members in an amusement machine incorporating a detector according to the invention; Figure 2 is an exploded perspective view of the reel member shown in Fig. 1; Figure 3 is a side elevation of the reel member shown in Fig. 1; Figure 4 is an exploded front elevation of the reel member shown in Fig. 1; and Figure 5 is a circuit diagram of the circuit on one component of the detector.

Referring to Fig. 1, one reel member 10 of a set of such reel members is shown. The reel member 10 is the end one of a set of reel members and is mounted for rotation on a central spindle (not shown) by means of a spacing bush 12.

A conventional notched stepping disc 11 is secured to the spacing bush 1 2 so that rotation of the reels can be controlled by a pawl 1 3 and associated electro-magnetic pawl-actuator 14.

As can be seen more clearly in Fig. 2 the reel assembly includes a first detector plate 1 5 which is secured to the spacing bush 1 2 adjacent and contiguous with the notched stepping disc 11. A dielectric disc 1 6 having a central aperture 31 is arranged on the face of detector plate 1 5 remote from the reel 1 0.

A second detector plate 1 7 is fixed to an end plate 1 8 of the reel assembly by means of screw 19, washer 20 and spring 21. One edge of the rectangular second detector plate 1 7 includes a semi-circular recess 32 of the same diameter of the central aperture in the disc 1 6 the dimensions being such that both the aperture 31 and recess 32 receive the reduced diameter portion 22 of the securing flange 23.The securing flange 23 has three apertures 24 to receive screws 25 which pass through corresponding apertures in the first detector plate 15, the stepping disc 11 and are received in apertures in the bush 1 2. Thus the reel 10, stepping disc 11, first detector plate 1 5 and fixing flange 23 rotate together relative to the reel end plate 1 8 and the second detector plate 1 7 whilst the dielectric disc 1 6 is free to rotate between the first and second detector plates.

The reel shown in Fig. 2 is the left hand end reel of an assembly of three such reels and the assembly end plate 26 is provided to hold the reel assembly together. The central spindle (not shown) passes through a washer and spring arrangement to a flange 27 having a reduced diameter portion 28 which locates in a slot 29 in the end plate 26 and is retained by means of a circlip 30.

Referring to Fig. 3 it can be seen that the side face of the first detector plate 1 5 is provided with a plurality of copper, electrodes only one of which is identified by the reference numeral 31. The detector plate 1 5 comprises an insulating material and the electrodes 31 are arranged in a predetermined radially distributed coded pattern which provides a discrete individual five element code which corresponds to each individual position in which the reel member 10 can stop as determined by the notched stepping disc 11.

The five elements for one position of the reel member are indicated by the references a, b, c, dand ein Fig. 3.

The second detector plate 1 7 has a printed circuit on its surface which circuit comprises five pairs of electrodes one electrode f each pair being connected together and the second electrode of each pair being connected to an individual lead. The five pairs of electrodes are arranged linearly to correspond to the radial electrode code on the first detector disc 1 5 so that the five pairs of electrodes are each capable of detecting, by virtue of the capacity, the presence or absence of an electrode 31 on the first detector plate 1 5. Thus any position of the reel member a binary code of five elements will be available at the output of the second detector plate and this binary code can be utilised to indicate the actual position of the reel member 10.

The use of five pairs of electrodes enables thirty-two discrete positions to be detected but it will be appreciated that if a further number of positions are required to be detected then an increased number of pairs of electrodes on the second detector plate 1 7 and corresponding electrode patterns on the first detector plate 15 can be employed.

The dielectric disc 1 6 may be a polyethylene disc and this serves as a dielectric medium for the capacitance developed between the electrodes of the first and second detector plates.

The circuit of the second detector plate 1 7 is shown in Fig. 5. The five pairs of electrodes are represented by C1 to C5 corresponding to the five electrode positions in each radial line of electrodes on the first detector plate 1 5.

One electrode of each pair is connected to a common line CK whilst the other electrode is connected to a respective resistor R, to R5 and a respective inverter V1 to V5 and diode D, to D5. The output LS corresponds to the first integer of a five-component binary code and the output MS corresponds to the last inter of the code.

The outputs LS-MS are connected to appropriate interface circuitry whereby the coded information as to the position of the reel can be utilised to provide the corresponding machine function.

It will be apparent that the present invention provides an extremely simple, effective and reliable method of detecting the position of a movable member. The fact that capacitance is employed to give an indication of the position means that there need be no moving electrical contacts which tend to be unreliable due to wear and contamination by extraneous matter.

Claims

1. A detector system for detecting the position of a movable member relative to a reference position said detector system comprising a first detector member associated with said movable member and movable in response to movement of said movable member and a second detector member associated with said reference position, each detector member being provided with at least one electrode and said detector members being positioned relative to one another to provide an electrical capacitance between said electrodes at one or more predetermined relative positions of said detector members whereby the position of the movable member can be detected.

2. A detector system according to Claim 1 in which a plurality of electrodes are arranged in a plurality of lines corresponding to positions of the member so that the combination of electrodes in any one line corresponds to a code which can be used to identify the position of the movable member.

3. A detector system according to Claim 2 in which the code is a binary code.

4. A detector system according to any of Claims 1 to 3 in which the movable member is a rotatable member and the first detector member is arranged to rotate therewith.

5. A detector system according to Claim 4 in which the detector member is in the form of a disc having electrodes arranged in radial lines on a flat surface thereof.

6. A detector system according to any of Claims 1 to 5 in which the second detector member is provided with a plurality of electrodes corresponding to the maximum number of electrodes present in any one line on the first detector member.

7. A detector system according to Claim 6 in which the second detector member is a plate fixed relative to the first detector member.

8. A detector system according to Claim 6 or 7 in which the electrodes on the first detector member form part of a printed circuit.

9. A detector system according to any of Claim 1 to 8 in which a dielectric material is interposed between the first and second detector members.

10. A detector system according to Claim 9 in hich the dielectric material is a plastics material.

11. A detector system substantially as herein described with reference to and as shown in theaccompanying drawings.

1 2. An amusement machine incorporating at least one reel member, the or each reel member being associated with a detector system as claimed in any of Claims 1 to 11.