GB2159269A - Optical score identifier for target games - Google Patents

Abstract

The position of a projectile e.g. a dart in a board 1 is detected by two closely-spaced planes of scanning beams just above and parallel to the board surface and by linear detectors 7 on which the shadow of a projectile is cast in x and y directions in each scanning plane. The data recorded from one scanning plane is processed to determine the sector in which the projectile lies. Close to boundaries between sectors the data from the other plane is also used to calculate the exact point of impact of inclined projectiles. Two pairs of parallel beams from sources 4 may be directed onto scanned CCD arrays by shallow lenses 8. Alternatively single narrow beams are scanned in x and y directions across the board onto a strip detector comprising a series of photosensitive regions to produce pulses which are connected until the shadow of a projectile is detected by a continuous photosensitive stripe extend along the strip. <IMAGE>

Description

SPECIFICATION Optical score identifier for target boards in projectile games The invention relates to the field of optical identification of target segments in projectile games where the requirement is to evaluate the result of a throw upon a target board by self-acting means.

From a range of various possible ap proaches to the problem this one has been selected because it signifies the exclusion of moving parts and the elimination of alignment and lense focussing preparations. The selected solution approach is further signified by a minimum of space needed between the board and the optical sensors; and the optical path can in no circumstances accidentally interfered with by the action of the players or the viewers. A further important aspect of the invention is that no expensive video tubes and resolving circuitry are required, and the optoelectrical signals are such that they could be processed in a programmable micro-processor.

These features are embodied in an optical scanning system which uses a pointlike source of light for each quarter sector of the round board directed by their lense segments to pass light or infra-red radiation across the board close to its surface; and opto-electronic pickup devices which will sense and locate the shadow cast upon it by a dart stuck in the board.

An example of an embodiment of the invention by way of a particular technical execution is explained hereunder with reference to FIGURE 1 which is a cross-sectional view B B through Fig. 2 FIGURE 2 which is a tope view of the arrangement according to Fig. 1.

FIGURE 3 which indicates the coordinates of an optically assessed dart position FIGURE 4a, 4b, 4c which give the sequential steps for electronically retrieving and processing the information with respect to the three-dart throw in a dart board game. The dartboard 1 is placed into a traylike frame 2 in such a manner that a minor clearance exists between the circumference of the board and the frame to take account of the dimensional tolerance of different makes. The board is accurately positioned with respect to markings on the frame 2 and then fixed by means of brackets and pressure screws (not shown).

Between the traylike frame 2 and the top cover 3 are placed four double lenses (8', 82; 83, 84; 85, 86; 87, 88) whose thickness is only abouy 4 in to 3/8 in; there are four pointlike sources of radiation 141 8 42, 43 8 44.

excited by electrical power over connection terminals 6 in insulator rings 5, and finally there are four electro-optical sensors 71, 72, 73, 74. The radiation shades 12 merely serve to delimit the radiation which, in this example, passes through a lense piece 8 to the sensor 7 to whose quadrant it belongs. The relatively thin sheet of radiation e, from source 4' bundled by lens 8' passes thus at close range above the surface of the board 1 in parallel rays and is focussed by lenses 86 in such a manner that the entire lower half-disc of the board is imaged on the device 7' upon which the radiation from source 4' is condensed. A projectile or dart anywhere upon the lower half of the board would therefore be imaged as a shadow line at some point of the linear optical device 7'.Similarly, a shadow line would be produced by a dart stuck on the left half of the board, on the optical device 72; or, on device 74 when a dart is held somewhere on the right-hand half of the board. In other words, the four optical quadrants with which four optical devices are associated have the task of identifying the exact relative distance along the coordinates - y, - x, + y, + x (see also Fig. 3). This can be done in several ways of which this description presents a specific example.

The optical device chosen for this example is a shift register whose parallel data input lines are sourced by small photodiodes.

Charge coupled devices associated with optical inputs are available from stock. By first optically sampling the board field and subsequently shifting out the register serially into an external register, the data acquisition is realised as a shadow line at a particular x or y position. It re-appears (after the data stream passes through an inverter circuit) in the external register as a high level logic data bit amidst low level bits which represent the illuminated empty semi-circle board area.

It is thus possible to enter the x-y positions (see Fig. 3) of a dart after a first throw into an electronic register having similar x-y coordinates. The optical sampling of a CCD device 7 consists essentially of a paralell input phase lasting but a short period preceded and followed by a state of readiness for serial data presentation to the outside world.

The first sampling, when a game begins, may be initated by a board-mounted impact sensor on arrival of the first dart. The electrical circuit receiving the shock pulse from a transducer would produce a delay to allow all portions to consolidate and thereafter the optical devices (7) will make the first parallel data entry into their linear registers. The logics of the sequential readout for the first three throws is broken down into discrete steps as surveyed in Figs. 4a, 4b and 4c. The described sequences are self-evident and need therefore not be commented upon further; except that our reason should be given for the need of the decision element D3-b/1 in Fig.

4c. The same reads: "Was a coordinate of the second throw also missing?". It is namely possible, that the first and second throws yielded clearly distinguishable pairs of x-y coordinates but the third throw is such that one of the coordinates is in perfect line with one of the coordinates of the two preceding throws. In that case it is is not possible for the machine to know which of the two preceding x or y coordinates are involved. Therefore, sequence step D3 b/3 prescribes that both the x (or both the y) coordinates of the first and second throw alongside the missing third coordinate information are displayed in a display sector reserved for manual decision as indicated in the sequence step D3 b/3 of Fig.

4c.

There remains to be explained how the coordinates can be used for identifying one of the twenty dart board sectors and one of the four segments in each sector. Both of these are basically in a polar coordinate system, and also the dividing lines between sectors and segments can most easily be defined in a polar coordinate system.

Further logics and electronics therefore required to convert the optically retrieved x-y positions of darts on the board into a polar (R, (p) reference system, and thereafter to compare the polar dart position data with those of the border lines so as to arrive at a weighted score in terms of the game.

The accuracy of this definition is dependent on the number of decimal digits used in defining the radial dimension R and the tangent (p of the angle (p. (Fig. 3). Tangent (p is the ratio x y Each dart position is defined by the radial dimension R =.\/X2 = YH and the angle ç be- tween the x-axis and R. In order to know into which sector a dart position falls only tangent (p need be considered. All the twenty radial sector division lines can be defined in terms of an angle q) which the radial sector border encloses with the + x coordinate. Therefore, a chain of comparisons of the dart positional tangent value with the said sector border tangent values will at some point show a change of sign, and that happens where a scored sector is.The purpose of the comparisons may be formulated thus: Is tangent (p (dart position) or than tangent g (sector border line)? A similar question leads to the identification of the segment, namely: Is R or then rO, r1, r2, r3, r4, r5 ? (wherein r0 is the radius of the innermost circle and r6 the radius of the outermost wire border circle. Where there is a change of sign in the comparison sequence, the segment is identified. Lists of tangent values for the 20 radial border lines may be held in ROM data storage devices; similarly the rio to r6 values for the segments.

The comparison processes may conveniently be programmed by means of a microprocessor. The same would also perform the calculation of the dart radius from the x-y coordinates after these are retrieved by the optical system, in the manner described.

After a sector is numerically identified this may then be converted into a sector score (for example sector 12, 5, 20, 1, 18 and so on) by hard-wired encoding circuits; the sector score is then multiplied with the segment weighting factor (for the segment at the outer periphery the weighting factor is 2, for the next one it is xl, then x3, then x 1; xl for the inner ring, and x2 for the bull's eye). The thereby resulting numbers may be displayed individually and/or added up in groups of three throws, and finally also deducted from the preceding score remnant and the result displayed.

The processing sequence Figs. 4a,b,c defines the principle of realizing the invention but does not describe in detail all the possible contingencies which must be taken into consideration for planning the program of a micro-processor; with due regard to the principles set out the detail programming would be a task well within the art.

A further refinement will now be described which is required to eliminate decision uncertainties in special cases. When a dart hits the board close to a border wire under an angle it could be that the shadow line da, (Fig. 5) produced by a light beam field DA, (perpendicular to the surface of the paper) would be just above the border wire. In that case the tangent g of the borderline wire concerned would be equal to the tangent g of the detected dart location and the difference between the two tgcp numbers when compared as described above, would be zero. The apparatus in that case could not decide whether a dart I or a dart II is responsible for this result (see Fig. 5). To resolve this drawback the invention provides for a second beam field layer DA2 which produces a second shadow line da2 on a second diode array linear retrieval sensor (7). This second sensor (7) would be placed right above the main sensor (7) so that it is exposed to the beamfield DA2.

If a dart happens to plough into the board in an exactly vertical position, the coordinates of that position in the lower and the upper sensors would be exactly the same, and the difference of their respective x and y numbers would be zero. However, if as shown in Fig. 5 the dart arrives at an angle, there will obviously be a difference in the coordinates as also in the derived polar coordinates (tangent , and R). It is now possible to program the use of these value differences in such a manner that dependent on whether they are positive or negative a clue is provided to the making of a logical decision on whether a dart has landed on one or the other side of a sector border line.Referring to Fig. 5, if the projected shadow line da2 is on the left of the segment or sector border wire, and respectively on the lift of the primary shadow line da1, this would clearly indicate that the dart is stuck to the right of the border wire. Vice versa, if the upper shadow line is on the right of the coordinate of the lower shadow line (da,), this would enable the processor circuit to decide that the dart has the position II and must be scored on the field to the left of the wire.

To execute this simple supplementary decision logic the system requires, as already said, two linear diode arrays and CCD registers (7) accurately set up in pairs. This does not require the generation of two separate light beam fields (DA, and DA2). A single beam field overlapping both may be provided which would illuminate the twio sensors of the sensor pair (7) at a lower and upper border level. As a rule, the date of the paired upper sensor would not be needed but would be called into play when the difference number of the compared borderline tangent (p values and the dart position values, or the difference of the borderline radius values and the dart position radius values drops below a preprogrammed minimum number.

To ensure that there is no build-up of heat due to the radiation within the largely enclosed shallow spaces of the optical scanning arrangement, the invention provides for air ventilation by means of a suction unit 11 (Fig.

1) which draws out air from the ante-chamber 10 and, via openings 9 in the frame 2 produces an air stream around the radiation lamps 43, 44. A similar ventilation provision is arranged for the space around the radiation lamps 4', 42 An alternative design for supplying the optical information to a microprocessor without changing the already described data processing procedure on the preceding pages 3 to 6 incl. will now be described. Its advantages compared with the design example of Fig. 1 and 2 are lower cost, easier alignment, less cross talk between the x and y data, lower power consumption by the light emitting devices and no generation of waste heat. These results are achieved basically by the following measures: Replacement of the micro-optic CCD integrated circuits (7) by relatively simple custom-made photo-sensor strips.Replacement of the lenses (8) by two precisionmoulded parabolically shaped bars on which a mirror-like deposit is attached. The four static lamps (4) are replaced by two rotating ultraviolet lasers producing a thin slit beam.

First, the new physical structure will be described (Fig. 6) and then the essential details given for the manner of obtaining the data and how the scores are displayed.

On a rigid, vertically suspended base plate 23 is mounted the dartboard 1, furthermore, two identical plates 26, and 262 perpendicular to each other. They measure for example 380 X 50mm and may be 5 mm thick. They may be covered by optical filter plates 27; or, the filter material may cover the plates as a kind of glazing. Details of the plate can be recognized in Fig. 7, top right corner, showing that the plate 26 has three conductor strips 52, 53 and 54. The spacing between stripes 52 and 53 is bridged by a uniform layer II of a photo-sensitive substance or a photo-voltaic junction strip. Equally, the space between conductor stripes 53 and 54 is bridged by a uniform layer I of the same substance. At the left side of the plate 26 there is another short conductor plate 59; the spacing between conductor 53 and 59 is again bridged by a photosensitive substance.

Returning to Fig. 6, the main base plate 23 carries two accurately positioned rotary beam generators 24' and 242. The preferred type would be slot laser emitters in the ultra-violet range, perhaps surrounded by a drum shell with a further thin slot to blend out stray radiation. The resulting very narrow beam sweeps across the mirror bar 25 (The beam from rotary device 241 sweeps across mirror bar 251, and that from device 242 sweeps across mirror bar 252). The two beams sweep over their respective reflectors sequentially.

Details of the reflector surface can be seen at the left upper corner of Fig. 7. The mirror deposit is limited to the strip m. Above that there are again two conductor stripes 55 and 56 the spacing of which has a continuous series of vertical lines (57) consisting of photo-electric or photo-voltaic substances. The pitch between neighbouring lines is 0.7 to 1 mm, screen printed or vacuum deposited through a mask. The beams would not be allowed to fall outside the mirror bar (251, 252) by suitable shielding plates (not shown).

The reflected beam traverses the dartboard 1 in horizontal and vertical directions respectively, and sweep across the faces of the two sensor plates 26.

The mode of operation made possible by the above layout, will now be explained with the aid of Fig. 7.

As the beam, from beam generator 241 or 242, traverses the mirror bar its lower portion is reflected by the mirror surface m whereas the upper portion makes the lines 57 sequentially conductive. The resistor 30 is alternately grounded and returns to a voltage given by the voltage divider 30-34. The potentiometer 34 is set so as to make the transistor T3 just conductive. At the output of the emitter-coupled inverter 41 is thus produced a train of clock pulses containing as many pulse spikes as there are lines on the strip 57. The spacing between the lines is arranged so that-if they were mirror lines-the beam reflected by them would produce equally spaced line projections upon the plate 26', or 262 respectively.The clock-pulses at the output of inverter 41 are conducted over wire 44 to the counter 48,' and the counter 48 - II 2 receives similar pulses from the second mirror bar 25 (not shown in Fig. 7). These counters have as may binary positions as needed for counting the number of lines on the mirror bar.

As the reflected beam traverses the photosensor plate 26' (-if there is not dart in the dartboard 1) the resistors 33 and 32 will be at a potential near ground level during the traversing period. That means, also the output from the inverter pairs 43 and 42 will be at a steady logic low. When, however, the traversing beam is interrupted at a given x-dimension a short logic high pulse will develope across the terminals of the inverters which will be passed on by wire 45 and 46 respectively.

Wire 45 leads to the enabling inputs e for the three-way AND gates 49'. The second input to these gates is a disabling input d controlled from the memory section 65. The third gate input are the binary output of the counter 48 1.

The purpose of the disabling input is explained in the flow diagrams 4 a to 4c; during any first scanning cycle, all the disabling inputs are high. Therefore, at whatever moment the scanning beam is interrupted by a dart, the binary combination of the gate outputs will reflect the exact distance of the shadow projection on th scanning strip 26' from the beam starting point. One may define this distance as the produce of the clock pulse number coincident with the dart shadow projection multipled by a unit length. The unit length is of no interest in the further processing in the microprocessor M1 which converts the x-y coordinates into polar coordinates tgg and R. This is done in cooperation with library data held in the memory section 65.After producing the polar dimension data these are transferred to the microprocessor M3 via paralell data lines 77. A very similar event takes place with respect to the optical information from the scanning line II of the plate 26' (compare line DA2 in Fig. 5). It should be noted here that Fig. 7 is only illustrating the manner of procuring the x-dimension data. A similar not shown circuit is required for produce the y- dimension data which are presented to the microprocessor M1 at i,. In the microprocessor M3 the attitude angle deviation from the desirable 90 dart entry is calculated and possibly displayed on a screen.

(It may be considered one of the criteria of the skilled player). Next, the polar position data with due regard to any correction necessary on account of the said attitude angle are compared with the polar library data contained in the memory section 65 for the fixed dart segment border lines and this comparison identifies the exact position of the dart as being within one or another board segment.

Once the board segment is identified the output is passed to a weighting circuit 64 in accordance with the standard scores associated with a dart game. These score numbers are displayed for the first, second and third throw in columns a of the display sections 69 and 70 (for the two players) of the display unit 71.

In column a the three part throw scoring numbers are detailed and the sum is automatically produced by an initiating signal from the part throw counter 50. The same is stepped up on receipt of a pulse IMP from an impact transducer (not shown) which senses the arrival of a dart on the dart board. However, a similar signal may be obtained from the gates 49, which may be preferable. When there are two darts in the board, the scanning unit would sense the shadows from both darts, and one method for dealing with one dart at a time would be to pass the binary data for the first dart held in memory in sector 65 to the gates 49 as disabling data; therefore only the data for the second dart would be entered into the microprocessor. In this simplified form the procedure would not be satisfactory; the elimination of the earlier data must be done intelligently in a sequence of steps to be programmed.

After the third part throw (corresponding to output position "2" of the part-throw counter 50) the player must go to the board and before extracting the darts will press the button 'EXT.R.'. after which the result is displayed and the counter readied for the next throw cycle. Alternatively, if switch sw is closed, this occurs automatically. If a dart misses its target and* falls to the ground, the player must press button 'MTH' (manual throw) so that the display of the part-throws is shown in the correct order; the score would of course be zero.

The system according to the invention also provides for a method of monitoring the alignment of the system against the position of the dartboard used. To this end, pins having the same thickness as those used in darts, can be clipped to the outer border wire bw of the dart board 1. (Fig. 6). Basically four pins suffice, namely in the x-dimension pins w and e, and in the y-dimensions pins n and s.

A fifth one in the center C is added. Thereafter, the machine is switched on. A monitoring instrument 28 has two columns of lamps, the one on the left for the y-dimension comprising lamps marked s c n, and the right column for the x-dimension comprising lamps marked e c w. There are two rows, simply for the two sensor planes I and II since each must work well to give reliable dart positions especially when darts comes down under an angle, near a segment border. When all the lamps are alight, the system is properly aligned. If one or another lamp remains dark this gives an indication where misalignment exists and can therefore be adjusted accordingly. The knobs 29 and 30 permit small phase changes in the clock-pulse train to allow for circuit delays.

Claims (2)

1. An optical score identifier for target boards in projectile games, wherein are provided two optical scanning dimensions (for example horizontal and vertical) and, for each scanning dimension, two planes of scanning beams separated by a small distance just above and paralell with the target board surface, furthermore electro-optical beam receiving means for translating illumination variations due to a shadow effect of a projectile retained by the Board after impact, into corresponding electrical variations, memory devices to which said variations are transferred to reflect the spatial shadow projection in each of said dimensions and scanning planes, and electronic processing means for translating the said memorized location marks into the customary target sectors, and to display said sectors accordingly.

2. An optical score identifier for target boards in projectile games as in Claim 1 wherein the said electronic processing means comprise a correction program for detecting differences in the location of a projectile in the said two scanning planes for each dimension, and to evaluate these differences in terms of an angle of inclination of the projectile, to calculate therefrom the exact point of impact on the target board, and to display or otherwise record in humanly readable form said corrected impact point and said angle of inclination.