Electronic game with infrared emitter and sensor

A hand-held electronic toy gun and target apparatus facilitating a game of tag using infrared light communications between a plurality of players. An electronic controller is coupled to a transmitter for sending a series of encoded infrared light signals and a receiver for detecting infrared light signals. A gun body enclosing the controller, transmitter and receiver combination includes a handle with at least one hand operable trigger and a housing atop the handle conforming to the player's wrist and forearm. The housing has a top portion for mounting a non-planar surface of a target window for exposing the target window upwardly and outwardly over a wide range of side angles. The housing further includes a front end portion forward of the handle for positioning an infrared light lens for focussing the series of encoded infrared light signals from the transmitter outwardly from the housing.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention relates to electronic games and, more particularly, to a gun 
and target apparatus facilitating a game of tag using infrared light 
communications between a plurality of players. A gun body for an 
electronic controller, infrared light transmitter and receiver combination 
includes a handle with at least one hand operable trigger and a housing 
atop the handle conforming to the player's wrist and forearm. The housing 
has a top portion for mounting an arcuate target window exposed upwardly 
and outwardly over a wide range of side angles. The housing also includes 
a front end portion forward of the handle for positioning an infrared 
light lens for focussing a series of encoded infrared light signals from 
the transmitter outwardly from the housing. The receiver includes one or 
more photodiodes for detecting infrared light biased by an inductive 
current source presenting a substantially higher alternating current than 
direct current circuit impedance, which tends to limit current changes 
from abrupt changes in illumination to avoid driving the infrared receiver 
into saturation. Each transmitter provides a signature series of encoded 
infrared light signals substantially longer in duration than abrupt 
changes in the illumination from background noise to discriminate the 
encoded infrared signals from the background noise at said receiver. 
2. Description of the Related Art 
Prior art infrared electronic games have been available since about 1985. 
For example, one prior art infrared electronic game, sold beginning in 
about 1986 by WORLDS OF WONDER under the trademark LAZER TAG, permitted 
players to fire invisible beams at one another with each player being 
provided with a game unit for emission of an infrared light beam. In the 
WORLDS OF WONDER game, a target was affixed to each player in order to 
count the number of "hits" registered by the target associated with each 
player. In the WORLDS OF WONDER game, a player was tagged "out" when 6 
hits were registered for that player. 
Infrared games are communication devices using infrared light beams, 
operating on the same principle as a remote control for a television set 
or a videocassette recorder. Efforts have been made to operate prior art 
infrared games in the very harsh environment of direct and indirect 
sunlight, as well as in the environment of indoor lighting. These various 
environments have made it extremely difficult to reliably communicate from 
an emitting unit to a target. Numerous efforts have been made to deal with 
harsh lighting environments, with various techniques and varying degrees 
of success. 
A need exists for infrared communication systems for use with electronic 
games having infrared emitters and sensors so as to better address the 
various lighting environments making it difficult to reliably communicate 
from an emitting unit to a target in a game setting. Additionally, it 
would be desirable to provide cost effective encoding of digital infrared 
signals to insure communication between various apparatus, and further to 
provide special features when communicating between these apparatus. An 
enhanced user interface for the players of such games may also find 
multiple input switches or triggers advantageous for providing multiple 
modes of play to make such game more interesting and challenging. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide an infrared emitter and 
sensor that overcomes the disadvantages and problems of prior art 
electronic games using infrared transmitters and receivers. 
It is another object of the invention to provide a gun apparatus for 
facilitating a game of tag using infrared light communications between a 
plurality of players. 
It is another object of the invention to provide an apparatus for 
facilitating a game of tag using infrared light communications between a 
plurality of players, each player being equipped with the gun and target. 
It is yet another object of the invention to provide a target apparatus for 
facilitating a game of tag using infrared light communications between a 
plurality of players. 
It is a further object of the invention to provide a method of facilitating 
a game of tag using infrared light communications between a plurality of 
players. 
An electronic game is described incorporating improved infrared 
communications to better discriminate encoded infrared signals from the 
background noise at the infrared receiver target, and enhanced game 
capabilities increase the interest in the game and the entertainment value 
for the players. A series of encoded infrared light signals sent with an 
infrared transmitter provides a signature signal substantially longer in 
duration than abrupt changes in lighting conditions to achieve improved 
performance in indoor light and direct and indirect sunlight. The infrared 
receiver includes at least one photodiode for detecting infrared light 
with the photodiode being biased by an inductive current source presenting 
a substantially higher alternating current than direct current circuit 
impedance to limit current changes from abrupt changes in lighting to 
avoid saturating the receiver. 
Briefly summarized, the present invention relates to a gun apparatus 
facilitating a game of tag using infrared light communications between a 
plurality of players. An electronic controller is coupled to a transmitter 
for sending a series of encoded infrared light signals and a receiver for 
detecting infrared light signals. A gun body enclosing the controller 
includes a handle with at least one hand operable trigger switch and a 
housing attached to the handle which may be conformed to the player's 
wrist and forearm. The housing has a front end portion forward of the 
handle for positioning an infrared light lens for focussing the series of 
encoded infrared light signals from the transmitter outwardly from the 
housing. The trigger switch may be operable with the controller for 
inhibiting the receiver for a predetermined period of time. Alternatively, 
a plurality of such switches may be provided as being operable in 
combination for either inhibiting said receiver for a predetermined period 
of time, or for sending a special function encoded infrared light signal, 
e.g., representative of a multiplicity of said series of encoded infrared 
light signals. 
Other objects and advantages of the present invention will become apparent 
to one of ordinary skill in the art, upon a perusal of the following 
specification and claims in light of the accompanying drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Referring now the drawings and especially to FIGS. 1 and 2, gun and target 
apparatus for facilitating a game of tag using infrared light 
communications between a plurality of players is shown with each player 
being equipped with the gun and target, the hand-held electronic game 
apparatus embodying the present invention is generally shown and 
identified by numeral 10. The apparatus 10 described herein includes a gun 
body 20, which as in the schematic drawing of FIG. 6, encloses an 
electronic controller 12 provided as a microcomputer herein from the SM5 
family of single-chip, four bit microcomputers available from Sharp 
Corporation, Japan, but any appropriate microcontroller or microprocessor 
may be employed in the described embodiment. The described gun and target 
apparatus for facilitating a game of tag using infrared light 
communications between a plurality of players described herein equips each 
player with a gun and target combination which includes at least one hand 
operable trigger, herein trigger 14A and special effects button 14B, 
coupled to the controller 12. Additional input switches may be employed 
for communication between the player and the controller 12. A transmitter 
16 indicated by dash lines is coupled to the controller 12 for sending a 
series of encoded infrared light signals responsive to the trigger 14A 
and/or 14B, wherein the infrared light signals are indicated in FIG. 1 by 
dashed line 42. An infrared receiver 18 as indicated in the dashed line 
circuitry section of FIG. 6, coupled to the controller 12, detects the 
infrared light signals 42 from the apparatus 10. 
As shown in FIG. 2, the gun body 20 provides an on-off switch 22, and 
several indicator lights 24A-24E which may be used for scoring as 
described below. A speaker 26 is positioned in the gun body 20 wherein the 
controller 12 includes a sound generator for generating audio effects 
responsive to the transmitter 16, the receiver 18 and the hand operable 
trigger switches 14A and 14B coupled to the controller 12. 
The gun body 20 enclosing the controller 12 includes a handle 28 for 
supporting the hand operable trigger switches 14A and 14B, and the gun 
body 20 also includes a housing 30 atop the handle 28 which as shown 
conforms to the player's wrist and forearm with a VELCRO e.g., hook and 
loop type fastener material strap 38 plus securing the player's forearm 
and hand shown in broken lines as reference numeral 40 in FIG. 1, for 
operation of the apparatus 10. The side view of FIG. 2 also shows a target 
window 32 having a non-planar surface which includes upstanding target 
sight 34 for aiming the gun and target apparatus 10. An infrared lens 36 
at a forward end portion of the gun housing 22 is used to focus infrared 
light transmitted from the transmitter 16 away from the gun body 20. 
Turning now to FIG. 3A, a top plan view of the hand-held electronic game 
apparatus 10 shows the target window 32 at the forward end of the housing 
30 near the infrared light lens 36. Thus, the housing 30 includes a top 
portion for mounting the non-planar surface of the target window 32 for 
exposing the target window upwardly and outwardly over a wide range of 
side angles, herein providing a 360 degree infrared light sensor for 
allowing hits from infrared light from other apparatus 10 to be detected 
from 360 degrees around the player. The non-planar target window 32 is 
typically an infrared light filtering material for passing infrared light 
and filtering extraneous background light, but the target window may also 
be suited for providing a light indicator for indicating when a hit is 
received, so as to integrate the target window with a hit indicator which 
may be observed by the player. As described, the housing 30 further 
includes a front end portion for the handle 28 for positioning the 
infrared light lens 36 for focusing the series of encoded infrared light 
signals 42 from the transmitter 16 outwardly from the housing 30. 
Scoring for the game is indicated by the five (5) red LED's, 24A-24E shown 
in the exploded view of FIG. 3B on the top of the unit. During normal 
play, the LED's will flash sequentially. As described, the apparatus 10 
includes a plurality of visual indicators 24A-24E coupled to the 
electronic controller 12 responsive to the encoded infrared light signals 
42 detected at the receiver 18. Thus, a method of facilitating a game of 
tag using infrared light communications between a plurality of players is 
described wherein each player is equipped with the transmitter 16 which 
sends a series of encoded infrared light signals 42 towards another 
player. The method includes associating a target 32 with each player 
having a receiver 18 for detecting the encoded infrared light signals 42 
from each of the other players. Further, the gun body 40 provides for the 
transmitter at 16 and the receiver 18 and target 32 in combination. 
Thus, using the LED light indicators of reference numerals 24A-E provide a 
method wherein the counting of the number of encoded infrared light 
signals 42 detected from other players is performed. Hereafter, a 
disabling of the transmitter 18 from sending the series of infrared light 
signals 42 towards another player is performed responsive to the 
predetermined count of received encoded infrared light signals being 
detected from other players in the provided counting step described above. 
A typical game plan will be provided as follows, e.g., two (2) "hits" to 
eliminate one "life." Each single LED represents two (2) lives. The first 
hit changes the LED to a solid ON nearest the front of the unit. The third 
hit changes the second LED to solid on. The fifth hit changes the third 
LED to solid on. The game continues this way until 10 hits then the unit 
will indicate a game over and the LED's will turn off. Once a player has 
been hit, e.g., 10 times, the unit will not function until it is turned 
off and then on again. If the player does not turn the unit off, it will 
beep periodically to remind the player to turn it off. 
FIGS. 3C and 3D are exploded cross-sectional views of the target window 32. 
Herein, the non-planar surface of the target window 32 is provided as an 
arcuate surface 44. As described, the target window 32 may be constructed 
from a tinted filter material which passes infrared light. The infrared 
receiver 16 is thus positioned behind the target window 32 and as 
described below may include a plurality of photodiodes for detecting the 
infrared light over a wide range of angles. As described, the receiver 16 
may include three (3) photodiodes for detecting infrared light over 360 
degrees. The arcuate surface 44 of the target window 32, as will be 
appreciated below, positions the receiver 18 for exposure to light 
upwardly and outwardly over a wide range of angles. 
FIG. 4A shows a prior art infrared photodiode receiver circuit 50 in which 
a photodiode 52 is biased by a resister 54, e.g., 39 KHz, and a 
capacitively coupled to an infrared amplifier 56 by a capacitor 58. The 
prior art receiver circuit 50 typically provides a direct current biased 
resistance of 38 KHz and an alternating current load of 39 KHz as well. 
FIG. 4B on the other hand shows receiver circuit 18 in which the 
photodiode 52 is biased with an inductive load, herein a 200 millihenry 
inductor 60. 
The relatively large inductive impedance provided in the bias circuit of 
FIG. 4B representing the infrared receiver 18 provides a low resistive 
direct current biases of approximately ohms, while providing an 
alternating current load of approximately 37.7 KHz. Thus, the receiver 18 
includes at least one photodiode 52 being biased by an inductive current 
source presenting a substantially higher alternating current (AC) than 
direct current (DC) circuit impedance to limit current changes from abrupt 
changes in the illumination of the photodiode 52 and to avoid driving the 
receiver 18 into saturation. Moreover, the target window 32 for the 
receiver 18 having the photodiode 52 positioned behind the target window 
32 provides for the photodiode 52 being exposed upwardly as well as 
orderly so as to position the receiver 18 for reception of background 
light signals, as well as for receiving signals from other apparatus 10. 
Thus, the receiver 18 is suited particularly for receiving the series of 
encoded infrared light signals 42 sent by other apparatus 10 so as to 
discriminate background noise at the receiver 18. 
Thus, optimal performance in both indoor light and direct and indirect 
sunlight is achieved with a low cost inductive bias circuit. The described 
techniques have been used to optimize the apparatus 10 for use in a noisy 
background environment. The receiver 18 uses a conventional reverse bias 
PIN Photodiode as the sensor. In this arrangement, current from the 
photodiode is transformed to an output voltage. This technique works very 
well when the ambient light level is relatively stable, such as typical 
indoor lighting. When extreme lighting conditions such as outdoor lighting 
are encountered, the current through the photodetector goes up very high 
and saturates the output because the bias resistor limits the amount of 
current the photodetector can draw. At the same time, high rejection of 
background noise is achieved. The bias resistor can be reduced to properly 
bias the photodiode, although the AC load on the photodiode output will be 
increased and this will reduce the AC output. 
The typical recommended bias circuit of prior art cannot work well in 
bright light conditions, because one of two effects will happen (1) the 
output saturates due to current limit from the bias resistor, or (2) the 
AC output from the photodiode is poor due to bias resistor loading when 
the resistor value is reduced for proper bias under high light. 
To solve this problem, the inductive bias circuit of FIG. 4B incorporates 
into the electronic game of the apparatus 10 which bias circuit uses a 
large inductor instead of a bias resistor. The large inductor has a high 
AC impedance at the center frequency of 30 KHz which minimizes the AC load 
and a low DC impedance of approximately 20 ohms. The DC bias circuit never 
becomes a current limit, therefore the photodiode remains active in all 
lighting conditions. 
High light conditions are characterized by a high degree of infrared noise. 
Most infrared (IR) communication devices such as TV remote controllers, 
etc., operate in relatively low light environments such as indoor 
lighting. The IR noise figure indoors is relatively low, the IR output 
signal from the remote controller is much stronger than background noise 
and therefore random noise is typically not a problem. Outdoors in 
sunlight the IR background noise level is very high compared to the signal 
from an IR emitter. 
FIG. 5A shows the typical IR transmission signal and FIG. 5B shows used 
with apparatus 10. Typical IR transmission schemes send multiple bits of 
data within one cycle. FIG. 5A shows 16 bits of data indicated by a 
reference numeral 62 with a 1 ms period each, the carrier frequency is 40 
KHz and the repeat period is 43 Ms. The signal used with the apparatus 10 
has only 3 bits of data with a 75 ms period each. The apparatus 10 game 
play does not need to send large amounts of data, it simply generates an 
IR signature that is easily readable through background noise. 
Characterizing random noise, it has been found that sunlight and some 
indoor lighting conditions can generate noise pulses of up to 7 ms in 
length. The typical IR transmission scheme cannot filter these pulses and 
therefore relies on repeating the pattern until a clear signal is received 
which, in some high noise environments, is virtually never. The electronic 
game of the apparatus 10 cannot rely on repeating the pattern, as this is 
a movement game and the target is constantly moving. One single burst, if 
on target, must hit, therefore an infrared light signature that could 
easily be detected through sunlight is used. 
The electronic game's signal indicated by reference numeral 64 has the 
signature of FIG. 5B has a 25 ms on time of a continuous 30 KHz carrier 
followed by a 50 ms off time. This pattern is repeated three (3) times. IR 
Signature is a long period which is easily implemented with low cost, slow 
toy grade microprocessors. This uncharacteristically long 25 ms on period 
allows for the detector to easily lock onto the signal and is far removed 
from the period of background noise. 
The schematic circuit diagram of FIG. 6 for the apparatus 10 shows the 
microcomputer 12 with the two triggers 14A and 14B that are attached to 
the handle of the apparatus 10. The main trigger 14A activates infrared 
data transmission while the special effects button 14B, the secondary 
trigger, activates various special features, described further below. 
Trigger switches 14A and 14B are coupled to the microcomputer 12 via port 
one as shown in FIG. 6. Visual indicators 24A-24E, herein light emitting 
diodes are also coupled to ports of the microcomputer 12, herein port 0 
and port 2. Port 2 of the microcomputer 12 is also used as an output for 
the transmitter 16 of the apparatus 10. 
The receiver 16 as shown in FIG. 6 includes three (3) photodiodes indicated 
in dash lines by reference numeral 52 which are by the 200 millihenry 
inductor 60 as discussed above. The three (3) photodiodes cover 360 
degrees infrared reception and are coupled to an infrared amplifier via 
capacitor 58. The infrared amplifier 56, herein KA2184, is a conventional 
electronic amplifier for use with the receiver circuit 18 to provide a 
digital output to port 0 of the microcomputer 12 for receiving the 
infrared coded data at the apparatus 10. Under digital control of the 
microcomputer 12, the input and output port may be used to provide several 
features for inhibiting and/or enhancing receiver 18 and transmitter 16 
operation, as described further below. 
The electronic game of the apparatus 10 has several features including a 
"Shields" feature and a "Mega Blast" feature. The Shields feature allows a 
player to effectively block a predetermined number of incoming hits or 
tags for a predetermined period of time, and send multiple signals or 
codes representing multiple signals. For example, three shields per game, 
each lasting three seconds, has been found to be satisfactory for the game 
play. Variations on these two parameters of the Shields feature are within 
the scope of the invention. The Mega Blast feature allows a player to tag 
out an opposing player with one hit. In a preferred embodiment, the 
electronic game counts up to ten hits. The Mega Blast feature will deliver 
ten hits at once to tag a player out. 
The switch 22 shown in FIG. 6 is provided as a double pull double throw 
switch for coupling the battery power to the apparatus 10 such that 
transmitter 16 and receiver 18 circuits are grounded when the switch 22 is 
in its off position. FIG. 6 also shows the visual and audio effects 
provided for the apparatus 10 when either the transmitter 16 via trigger 
14A and/or 14B emit infrared signals with associated sound effects or the 
receiver 18 indicating the reception of infrared signals with 
corresponding audio visual effects for the player. More particularly, an 
incandescent light bulb 66 is driven by port 2 of the microcomputer 12 via 
a transistor, and a sound effects chip 68 coupled to ports 4 and 5 of the 
microcomputer 12 provide audio output to the speaker 26. A wide variety of 
the audio effects chips may be employed for providing several different 
audio effects associated with the use of the apparatus 10. 
To turn the apparatus 10 on, the player slides the ON/OFF switch 22 to the 
ON position. Sound effects indicate that the unit is power up. To emit a 
single infrared (laser) strike, press and release the main trigger 14A 
once. To emit a rapid continuous strike, press and hold the main trigger 
14A. The rapid/continuous strike may only be used for, e.g., five seconds 
at a time. After, e.g., five seconds, the unit will only be able to emit a 
single strike for, e.g., ten seconds. 
The Super Strike is a single strike with the power of ten (10) regular 
strikes. To activate Super Strike the player presses the regular trigger 
14A and the special feature trigger 14B at the same time. A player may, 
e.g., only use Super Strike once during a game so make sure it is used 
wisely. If Super Strike misses, e.g., it may not be used again. 
The Force Field allows a player to "block" a laser strike and avoid a "hit" 
from an opponent. To activate Force Field the player presses the special 
feature trigger 14B. The Force Field is activated for, e.g., three seconds 
during which your unit is shielded from any opponents. The FORCE FIELD may 
only be used, e.g., three times during a game. 
As discussed, the trigger 14A, and particularly the special effects button 
14B are used in the embodiment to provide the target 32 including the 
receiver 18 for detecting the infrared light signals 42 such that the 
target 32 is responsive at least one of the switches, i.e., special effect 
button 14B. Accordingly, at least one of the trigger switches 14A and/or 
14B is operable with the controller herein microcomputer 12 for inhibiting 
the receiver 18 for a predetermined period of time. 
Additionally, a plurality of such switches 14A and 14B may be operable in 
combination for inhibiting the receiver 18 for the predetermined period of 
time. As described above, the switches 14A and 14B are further operable 
for sending either an encoded infrared light signal 42 representative of a 
multiplicity of a series of encoded infrared light signals 42, and/or for 
sending a multiplicity of the series of encoded infrared light signals 42. 
To this end, the particular encoding of the several states of the encoded 
infrared light signal 42 may be itself representative of multiple such 
signals, or several signals may be transmitted through the combined 
operation of the triggers 14A and 14B. 
While there have been illustrated and described particular embodiments of 
the invention, it will be appreciated that numerous changes and 
modifications will occur to those skilled in the art, and it is intended 
in the appended claims to cover all those changes and modifications which 
fall within the true spirit and scope of the invention.