BACKGROUND OF THE INVENTION

As a result of technological advances in the high density integration of solid state circuits and the economical production of sophisticated microprocessors, microcircuits are being employed in an increasing variety of applications. Electronic circuitry is being added to consumer goods to perform functions not previously avail¬ able and to complement or improve existing functions. An example is the use of microcircuits in sporting goods. A particular example is the use of electronic signal eval- uation, decision-making and release command circuitry in a safety ski binding. Such an electronic safety ski binding is described in U.S. Patent 4,291,894. The elec¬ tronic safety ski binding described there includes a mechanical portion which, in its locked condition, grasps a skier's boot and, in its released condition, permits the ski boot to be separated from the binding. The re¬ leased condition is ideally achieved during skiing when skiing forces threaten the safety or well-being of the skier. The function of the mechanical portion of the safety ski binding is complemented, as described in the cited patent, by electronic circuitry which senses the skiing forcies, continuously evaluates them to determine if the skier is endangered and commands the mechanical ^• portion of the binding to release, i.e. to switch from its locked to released condition, when a situation dan¬ gerous to the skier is encountered. Another example of an application of electronic circuitry in sporting goods is in underwater diving equipment. There, the harshness of the environment and the necessity of isolating the circuitry from that environment is obvious.

Before sporting goods incorporating electronic circuitry may be used, the circuitry must be actuated or turned "on". Electrical switches for electronic sporting goods are described in U.S. Patent No. 4,140,331. The switches described there include at least one mechanical, moveable part controlling the connection of the circuitry and power supply. However, in the harsh environment ex¬ perienced by sporting goods and, particularly, ski bindings, it is desirable to avoid mechanical and move- able parts. Such parts imply the presence of sliding sur¬ faces which are the source of difficulty in avoiding ad¬ verse effects of mechanical shock and in protecting cir¬ cuitry against the intrusion of foreign matter. Accord¬ ingly, it is desirable to provide a switch which has only stationary parts for electronic circuitry in sporting goods.

SUMMARY OF THE INVENTION

In the present invention, an electrical switch is provided which incorporates an electronic switch. The electronic switch connects or disconnects the power supply arid electronic circuitry. Since the switch incor¬ porates electronics which must be constantly prepared to turn the electronic circuitry "on", some electrical power is continuously consumed by it. However, by constructing the inventive switch from conventional CMOS circuits, its power consumption is negligible.

The electronic switch is actuated by electronic switch control means which is responsive to an external influence. The control means may be oscillator-based so that an external influence, such as pressure, will change the tuning of the oscillator or of a filter receiving the output signal of the oscillator. The resultant frequency shift appears as a changed signal level at the filter

output which activates or deactivates the electronic switch. Another embodiment of a switch according to the invention includes, as an electronic switch control means, a piezoelectric crystal which generates a voltage 5 in response to a mechanical shock. The shock-generated voltage causes the electronic switch to turn on the elec¬ tronic circuitry. Still another embodiment of the inven¬ tive switch includes an inverter and a resistor network as a control means. A change in the input impedance of 10 the inverter brought about by a change in an external in¬ fluence causes the output signal of the inverter to change states, thereby directing the electronic switch to assume its "on" or "off" position.

BRIEF DESCRIPTION OF ^' THE DRAWINGS

15/ Figure l.-is a schematic, block diagram of a switch according to the invention.

Figure 2 is a schematic, block diagram of an embodiment of a switch according to the invention.

Figure 3 shows response curves as a function of 20. frequency for high and low pass filters.

Figure 4 depicts' in cross section a capacitor, both free of«and under the influence of pressure, which forms a part of a control means according to an embodiment of the invention. 5 Figure 5 is a schematic cross sectional view of a ski boot gripped by a ski binding including embodiments of the inventive switch.

Figure 6 presents schematic diagrams of cir¬ cuitry for inclusion in a control means according to em- 0 bodiments of the invention.

Figure 7 is a schematic diagram of an embodiment of a switch according to the invention.

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Figure 8 is a schematic diagram of an embodi¬ ment of a switch according to the invention incorporating a piezoelectric device.

Figure 9 is a schematic diagram of an embodiment of a switch according to the invention incorporating an inverter.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

In the present invention, an electrical switch that incorporates stationary parts, i.e., does not incor- porate moveable parts, is provided for electronic sports equipment. The switch is actuated by various external influences which may involve relative movements of ob¬ jects. The inventive switch itself does not incorporate any moveable parts, i.e., parts which pivot or otherwise cause the mechanical closing of electrical contacts.

The term "stationary parts" as used here, includes de- formable parts, i.e., parts which may change in dimension in response to the application of pressure to them, but which do not mechanically close or open electrical con- tacts as a result of the deformation. With the defini¬ tion of the term "stationary parts" thus understood, the switch according to the present invention includes only stationary parts and is free of the difficulties exper¬ ienced in using, in harsh sports equipment environment, switches which incorporate moveable parts.

In Fig. 1, a schematic block diagram of the functioning of the switch according to the invention is depicted. A power supply 1 supplies power to operate electronic circuitry 3 found in sports equipment. Be- tween power supply 1 and circuitry 3 is interposed an electrical switch 5, shown within the broken lines, com¬ prised of an electronic switch 7 connected directly be¬ tween supply 1 and circuitry 3. Electronic switch 7 is

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controlled, in response to an environmental influence, in its opening and closing by an electronic switch control means 9. Electronic switch 7 is a conventional elec¬ tronic switch, such as a transistor, which functions as a 5 closed or open switch between its two switched terminals depending upon the state of a signal presented at its con trol terminal.

In Fig. 2, an embodiment of the switch of Fig. is shown in which the control means incorporates an oscil 10 lator and filter. A power supply 11 is connected through an electronic switch 13 to power electronic circuitry 15. Power supply 11 is also connected to an oscillator 17, the output signal of which is supplied to a filter 19. The output signal of filter 19 is in turn applied through 15 an optional.latch means 21 to the control terminal of elec¬ tronic switch 13 to control the state, i.e., closed or open, of electronic switch 13. An environmentally vari- . able impedance means 23 is incorporated into either oscil¬ lator 17 or filter 19 for changing the value of an imped- 20 ance in response to an external influence. The impedance change causes the frequency of oscillator 17 to shift or the frequency response characteristic of filter 19 to shift. Ignoring latch means 21 for the moment, this shifting, if of sufficient magnitude, causes the state of 25 _. the signal at the control terminal of electronic switch 13 to change, opening or closing electronic switch 13.

The change in the magnitude of the output sig¬ nal of filter 19 is illustrated in Fig. 3 for the situa¬ tions in which filter 19 is a low pass and high pass fil- 30 ter. In Fig. 3A, the familiar linearized response char¬ acteristic of a low pass filter is shown. For a fixed amplitude input signal of variable frequency applied to the filter, an output signal appears which, above a cer¬ tain frequency, especially above cut-off frequency, fc' 5 has a much lower amplitude than does the input signal.

Input signals with frequencies below f are not attenuate appreciably by the filter. A threshold output signal am¬ plitude is indicated in Fig. 3A, the threshold referring to the control signal amplitude which, when applied to the control terminal of electronic switch 13, determines the state of electronic switch 13. Signals above the threshold amplitude cause switch 13 to be in one state (e.g., closed), while amplitudes below the threshold caus electronic switch 13 to be in its other state (e.g. , open) . If oscillator 17 is operating at frequency f, of Fig. 3A, the output signal from filter 19 is above the threshold. However, if variable impedance means 23 is incorporated in oscillator 17 and causes its frequency of oscillator 17 to shift in response to an environmental change, to frequency f- of Fig. 3A, then the filter out¬ put signal drops below the threshold level. In this manner, electronic switch 13 can be opened and closed in response to external influences. Likewise, as shown in Fig. 3B, the same result can be achieved with a high pass _* filter, the threshold being exceeded when the frequency of oscillator 17 rises from f_», below the cut-off fre¬ quency to f x , above the cut-off frequency.

Figs. 3A and 3B have been described as if a shift in oscillator frequency provided electronic switch control. The same response can be achieved through shifting the cut-off frequency of the filters by including the variable impedance means 23 in filter 19 rather than in oscillator 17. In that event, the cut-off frequency, f , would shift between f. and f~ in Fig. 3A, and between ₃ and f. in Fig. 3B, to change the state of electronic switch 13.

In Fig. 4, an example of an embodiment of an environmentally variable impedance means 23 is illustrated A capacitor 31 has an elastic dielectric material 33 dis- posed between its plates 35 and 37. Plate 37 is firmly

supported, but plate 35 is deformable or supported only by dielectric 33. As illustrated in Fig. 4B, pressure applied transversely to the two plates reduces their separation over at least part of their area, thereby raising the capacitance of the capacitor. If capacitor

31 is part of oscillator 17, the change in its capacitance changes the output frequency of the oscillator. If ca¬ pacitor 31 is part of filter 19, the change in its capa¬ citance changes the cut-off frequency of the filter. In either event, the state of electronic switch 13 may be changed by selecting the cut-off frequencies and frequency shifts in a manner obvious to one skilled in the art.

In application to a ski binding, the pressure on capacitor 31 may be provided by the weight of the skier. Capacitor 31 may be mounted on a binding where a ski boot will be in contact with it. By way of further illustration, Fig. 5 shows, in cross section, a ski boot 41, clamped by a toe clamp 43 and a heel clamp 45 in a ski binding. The binding includes a sole plate 47 in which an element 49, which may be capacitor 31, is em¬ bedded. The weight of the skier through the heel of the boot compresses the capacitor plates, triggering the elec¬ tronic switch. In a ski binding, it is important to avoid changing the "on" state of electronic switch 13 during skiing when weight may be absent from the boot heel, for example, during a jump. To achieve this result, the op¬ tional latch means 21 of Fig. 2 may be included in the circuit. As explained elsewhere in this description, latch means 21 maintains a fixed output signal once the proper input signal is received, regardless of subsequent changes in the input signal. Latch means 21 may only be reset by applying a signal to the release terminal of the latch. In applications other than ski bindings, latch means 21 may not be needed. For example, in diving equip- ent, the capacitor embodiment of the environmental

variable impedance means could be sensitive to water pres¬ sure so that so long as the equipment remained submerged, electronic circuitry 15 would remain "on". If the elec¬ tronic circuitry need only operate during submersion when 5 water pressure will be present, no latch means is neces¬ sary.

Another embodiment of an environmentally vari¬ able impedance means 23 can be constructed from a resis¬ tor having a resistance which depends upon the mechanical

10 pressure exerted on it. Such a variable conductance elas¬ tomer is sold under the trademark "Pressex", which, in the absence of pressure, acts as an open switch. Application of sufficient pressure compressing Pressex causes it to act as a closed switch. Thus, a pressure-sensitive switch

15 having only stationary parts may be formed to switch an impedance. In Fig. 6A, resistors R, and R, are connected in series with pressure-sensitive resistor R_ shunting resistor R ₃ . Resistor R _g is formed from Pressex and may be incorporated in a ski binding as element 49 of Fig. 5.

20 When ski boot 41 is present and the skier's weight applied to resistor R,_, that "resistor" essentially short circuits resistor R- causing a shift in the cut-off frequency of a filter, if the resistors are part of a filter, or a shift in frequency of an oscillator if the resistors form part

•25 _. of the oscillator's tuning circuit. The same variable resistance network is applicable to diving equipment. Likewise, in Fig. 6B,.a resistor R ₇ formed of Pressex shunts a capacitor C, which is connected in series with a capacitor C, . When sufficient pressure is applied to re-

30 sistor R_, it short circuits capacitor C-,. Thus, the capacitance presented across the terminals in Fig. 6B is either that of capacitor C, , or the series combination of C, and C-., depending upon the resistance of resistor R_. Again, the variable capacitance may be part of a filter

35 or of an oscillator's tuning circuit causing a shift in a

response characteristic or of frequency which translates into a critical change in the control signal applied to electronic switch 13. The variable capacitance means of Fig. 6B is applicable to ski bindings and diving equip- 5 ment just as previously described.

As Fig. 2 makes clear, oscillator 17 and elec¬ tronic switch 13 must be perpetually active or, at least, active when it is intended that electronic circuitry 15 may be turned on and off. It is preferable that oscilla- 10 tor 17 and electronic switch 13 be perpetually energized so that there is no possibility that another switch or preparatory step, which could be forgotten, is necessary to activate electronic circuitry 15. By constructing the electronic switch and oscillator from CMOS components, 15' the power perpetually consumed can be miniscule. For example, an oscillator built from a CD 40106 model Schmidt trigger would consume a current of only about 0.02 micro¬ amperes at 5 volts at 25 C or 1 microampere at 5 volts at -40 C, i.e. a maximum power of 5 microwatts. A battery 20 rated at 0.5 ampere-hours can theoretically supply such a power for about 57 years, far longer than its shelf life. Moreover, lithium cell batteries tend to "fall asleep" unless there is a minimal constant current flow. 'Thus, the continuous power consumption required by switches •25. according to the present invention is minimal, not detri¬ mental to battery life and may even be beneficial.

In Fig. 7, a schematic circuit diagram of an embodiment of a switch according to the present invention is shown. The power supply is in the form of a battery 30 V _R which is connected to electronic switch 51 ^' and, through it, to electronic circuitry 53. A conventional CMOS in¬ verter 55 has a feedback resistor R ₁ , and, connected from its input terminal to ground, a capacitor C. , . Thus, in¬ verter 55 with resistor R, , and capacitor C,, form a well- 35 known oscillator circuit. The output of the oscillator is connected to a simple low pass filter comprising a

series resistor R, ₂ , the opposite terminal of which ^' is grounded through a capacitor C. ₂ . The junction of R. ₂ and C,„ is connected to the anode of a diode D..,, the cathode of which is grounded through a capacitor C, ₃ . Diode D, , and capacitor C, ₃ form a peak detector which detects and stores on C, ₃ a voltage approximately equal to the amplitude peak of the voltage that appears on C, ₂ . Diode D, prevents discharge of C, ₃ into C, ₂ thereby more precisely transmitting changes in magnitude of the filter output signal to electronic switch 51. The. voltage on capacitor C, ₃ is applied directly to the control terminal of electronic switch 51.

Either one of capacitor C,, or C,- or one of resistors R, , or R, _ could comprise an environmentally variable impedance means as previously described. The variation of the value of the variable impedance tunes the oscillator or the cut-off frequency of the filter, so that the external influences, e.g., the application or removal of the skier's weight, the submersion or sur- facing of diving equipment, causes electronic switch 51 to switch electronic circuitry 53 on and off.

While the foregoing discussion described simple filters with single frequency breakpoints, more complex filters having a number of frequency breakpoints can also be used to advantage and are within the scope of the in¬ vention.

Another embodiment of a switch according to the present invention is shown in Fig. 8. This embodiment does not employ an oscillator; rather, the electronic switch'control means comprises a piezoelectric device.. The power supply, again V _β , is connected to electronic switch 61 and through it to electronic circuitry 63. V _β is also connected to one terminal of a piezoelectric de¬ vice 65. The other terminal of device 65 is connected to a terminal C of a latch means in the form of a D-Type

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flip flop 67. Input terminal D of flip flop 67 receives the power supply voltage from V„. The Q output terminal of flip flop 67 is connected to -the control "terminal Of ^■ electronic switch 61. Terminal S of flip flop 67 is 5 grounded and terminal R is prepared to receive a reset signal. The cathode of a zener diode D ₂ is connected to terminal C of flip flop 67 and its anode is grounded.

Piezoelectric device 65 is preferably a modern titanate bearing ceramic material which produces a 10 voltage in response to a mechanical shock. In modern piezoelectric devices this voltage can be very high; ^' zene diode D ₂ acts to limit the voltage received by terminal C of flip flop 67 and to prevent damage to the flip flop. When the switch is first awaiting a turn-on stimulus, the 15 output signal of flip flop 67 at terminal Q is in its low state. When a piezoelectric voltage large enough to clock flip flop 67 is produced and received at input terminal C of flip flop 67, the output signal at terminal Q of flip flop 67 switches to its high state, causing elec- 20 tronic switch 61 to change state. Thereafter, changes in the input voltage at terminal C have no effect on the state of the signal at the Q terminal so long as no reset signal is received at terminal R of flip flop 67. That is, flip flop 67 acts as a latch, holding the signal. from •25. device 65 and applying it to electronic switch 61 so long as the flip flop remains latched. The output signal at terminal Q is reset to its low state when a reset pulse is applied to terminal R of flip flop 67. The reset sig¬ nal may be provided by electronic circuitry 6e when some 30 critical point is reached. For example, in a ski binding, the releasing of the binding, either voluntarily by a skier at the end of a ski run, or involuntarily to prevent injury to the skier, would be an appropriate time for re¬ setting the Q terminal signal to its low state.

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When the piezoelectric embodiment of the switch is used in a ski binding, the insertion of a boot in the binding may be the source of the mechanical shock turning the switch "on". In the illustration of Fig. 5, element 49 could be the piezoelectric device, the heel of boot 41 generating the actuating shock. Of course, during skiing various other mechanical shocks are generated. In order to avoid repeated switching in response to these shocks, the latch means is provided. In addition, since the out- put signal of piezoelectric device 65 is transitory, the latch means "freezes" that signal to keep electronic switch 61 actuated after the stimulating signal has fallen to zero.

The same embodiment of a latch means, a flip flop, could be used as latch means 21 of Fig. 2. In an embodiment of the invention in which a switch is actuated by a skier's weight, the latch means maintains the elec¬ tronic circuitry "on" when the skier jumps or the skis vibrate during skiing, by functioning in the manner de- scribed for the piezoelectric embodiment.

Yet another embodiment of a switch according to the invention is shown schematically in Fig. 9. There, power- supply V _β is connected to an electronic switch 71 and through it to electronic circuitry 73. The power supply is connected through a resistor R ₂ , to an inverter 75. The output of inverter 75 is connected to the control terminal of electronic switch 71. There is also shown connected to the input of inverter 75 a wire which con¬ tains an open circuit having terminals 77 and 79, terminal 79 being grounded. When the input voltage to inverter 75 is high, its output signal is low and vice versa. The characteristics of inverter 75 are chosen so that voltage V represents a high level signal and a frac¬ tion of V _β , e.g., V„/ ₂ , represents a low level signal. When there is no connection or conduction across terminals

77 and 79, V _β is applied to the input of inverter 75. When an impedance is connected across the terminal 77 and 79, the input voltage drops, since. ₂ , is'in se ies:.with the formerly open conductive path. If the impedance con- 5 nected across the terminals is small enough, the input voltage to inverter 75 will change sufficiently to cause the output signal of inverter 75 to go high, actuating electronic switch 71. By choosing the resistance of R ₂ , to be very high, e.g., 100 megohms, the connection across 10 open terminals 77 and 79 need only be what might normally be considered a leakage path having an impedance of 20 megohms or- so in order to switch the state of the output signal of inverter 75. In diving equipment, the open connections need only be exposed terminals which are 15 closed by the conductivity of water when the equipment is submerged. In a ski binding, rather than element 49 of Fig. 5, terminals 77 and 79 may be contained in and be flush with the upper surface of sole plate 47. In that configuration, the presence of ski boot 41 creates a 20 leakage path of sufficiently low impedance to cause the output signal of inverter 75 to switch to its high . state. Removal of the conducting path by removal of a ski boot from the binding, again causes the output signal of in¬ verter 75 to assume its low state, inverting the state of •25, electronic switch 71. Thus, electronic switch 71 is con¬ trolled by whether or not a leakage path is provided be¬ tween terminals 77 and 79.

The invention has been described with reference to certain preferred embodiments. Those skilled in the 30 art will recognize that various additions, substitutions and modifications may be made without departing from the spirit of the invention. Therefore, the scope of the in¬ vention is limited solely by the following claims.

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