EP0105928B1

EP0105928B1 - Switch for electronic sports equipment

Info

Publication number: EP0105928B1
Application number: EP19830901966
Authority: EP
Inventors: Nicholas F. D'antonio; Ehrenfreid Andra; Lorenz Stempfhuber
Original assignee: Marker International Co; Kinetronic Industries Inc
Current assignee: Marker International Co; Kinetronic Industries Inc
Priority date: 1982-04-12
Filing date: 1983-04-07
Publication date: 1991-07-31
Also published as: DE3382362D1; WO1983003555A1; EP0105928A4; EP0105928A1

Abstract

In electronic equipment used in sports performed in harsh environments, such as electronic ski bindings, switches may malfunction due to the effects on movable parts of mechanical shocks and the intrusion of foreign matter. To overcome these problems, an electrical switch (5) for electronic sports equipment comprises an electronic switch (7) and an electronic switch control (9) for controlling the state of the electronic switch in response to external influence, the electronic switch (7) and the electronic switch control (9) being stationary devices.

Description

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 available 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 evaluation, 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 electronic 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 released 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 forces, 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 dangerous to the skier is encountered.
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.-A-. 4,140,331 or DE-A-2 705 174. 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 experienced by ski bindings, it is desirable to avoid mechanical and moveable parts. Such parts imply the presence of sliding surfaces which are the source of difficulty in avoiding adverse effects of mechanical shock and in protecting circuitry against the intrusion of foreign matter. Accordingly, it is desirable to provide a switch which has only stationary parts for electronic circuitry in sporting goods It should be noted that (see paragraph 1 at page 20 of DE-A-2705174) it is known to control an on/off-switch by changing the magnetic flux between a step-in postion and a release position of the ski boot. Also, instead of said on/off-switch an optical interrupting means can be used which covers the ski boot during a step-in operation.
US-A-3,892,980 discloses a releasable ski binding device in which the release mechanism is electrically actuated by signals generated by a plurality of pressure sensors mounted in proximity to a ski boot. Attention is also drawn to US-A-4,310,807.
The present invention relates to an electronic ski binding as set forth in the preamble of claim 1, and is characterized by the features of the characterizing part of claim 1. Prefered embodiments of the invention are disclosed in the dependent claims. The electronic switch is actuated by electronic switch control means which is responsive to an external influence. The control means is 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. The influence mentioned above should be additionally defined as an effect of the skiboots and of ordinary skiing conditions. In this context, it shall be noticed that extraordinary skiing conditions would give rise to a releasing reaction of the ordinary circuitry of the ski binding.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 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 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.
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 circuitry for inclusion in a control means according to embodiments of the invention.
Figure 7 is a schematic diagram of an embodiment of a switch according to the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

In the present invention, an electrical switch that incorporates stationary parts, i.e., does not incorporate moveable parts, is provided.
The switch is actuated by various external influences which may involve relative movements of objects. 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 deformable 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 contacts as a result of the deformation. With the definition of the term "stationary parts" thus understood, the switch according to the present invention includes only stationary parts and is free of the difficulties experienced 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. Between power supply 1 and circuitry 3 is interposed an electrical switch 5, shown within the broken lines, comprised of an electronic switch 7 connected directly between supply 1 and circuitry 3. Electronic switch 7 is 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 electronic switch, such as a transistor, which functions as a closed or open switch between its two switched terminals depending upon the state of a signal presented at its control terminal.
In Fig. 2, an embodiment of the switch of Fig. 1 is shown in which the control means incorporates an oscillator 17 and a filter 19. A power supply 11 is connected through an electronic switch 13 to power electronic circuitry 15. Power supply 11 is also connected to oscillator 17, the output signal of which is supplied to filter 19. The output signal of filter 19 is in turn applied through an optional latch means 21 to the control terminal of electronic switch 13 to control the state, i.e., closed or open, of electronic switch 13. An environmentally variable impedance means 23 is incorporated into either oscillator 17 or filter 19 for changing the value of an impedance 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 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 signal of filter 19 is illustrated in Fig. 3 for the situations in which filter 19 is a low pass and high pass filter. In Fig. 3A, the familiar linearized response characteristic 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 certain frequency, especially above cut-off frequency, f_c, has a much lower amplitude than does the input signal. Input signals with frequencies below f_c are not attenuated appreciably by the filters 19. A threshold output signal amplitude 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 cause electronic switch 13 to be in its other state (e.g., open). If oscillator 17 is operating at frequency f₁ 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 f₂ of Fig. 3A, then the filter output 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 f₃, below the cut-off frequency to f₄, 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_c, would shift between f₁ and f₂ in Fig. 3A, and between f₃ and f₄ 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 disposed 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 capacitor 31 is part of filter 19, the change in its capacitance 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 embedded. The weight of the skier through the heel of the boot compresses the capacitor plates, triggering the electronic 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 optional 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.
Another embodiment of an environmentally variable impedance means 23 can be constructed from a resistor having a resistance which depends upon the mechanical pressure exerted on it. Such a variable conductance elastomer 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 having only stationary parts may be formed to switch an impedance. In Fig. 6A, resistors R₁ and R₃ are connected in series with pressure-sensitive resistor R₅ shunting resistor R₃. Resistor R₅ is formed from Pressex and may be incorporated in a ski binding as element 49 of Fig. 5. When ski boot 41 is present and the skier's weight applied to resistor R₅, that "resistor" essentially short circuits resistor R₃ 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 of the oscillator's tuning circuit. Likewise, in Fig. 6B, a resistor R₇ formed of Pressex shunts a capacitor C₃ which is connected in series with a capacitor C₁. When sufficient pressure is applied to resistor R₇, it short circuits capacitor C₃. Thus, the capacitance presented across the terminals in Fig. 6B is either that of capacitor C₁, or the series combination of C₁ and C₃, depending upon the resistance of resistor R₇. Again, the variable capacitance may be part of a filter 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.
As Fig. 2 makes clear, oscillator 17 and electronic 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 oscillator 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, 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 microamperes at 5 volts at 25^oC or 1 microampere at 5 volts at -40^oC, i.e. a maximum power of 5 microwatts. A battery 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 according to the present invention is minimal, not detrimental 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 V_B which is connected to electronic switch 51 and, through it, to electronic circuitry 53. A conventional CMOS inverter 55 has a feedback resistor R₁₁ and, connected from its input terminal to ground, a capacitor C₁₁. Thus, inverter 55 with resistor R₁₁ and capacitor C₁₁ form a well-known oscillator circuit. The output of the oscillator is connected to a simple low pass filter comprising a series resistor R₁₂, the opposite terminal of which is grounded through a capacitor C₁₂. The junction of R₁₂ and C₁₂ is connected to the anode of a diode D₁₁, the cathode of which is grounded through a capacitor C₁₃. Diode D₁₁ and capacitor C₁₃ form a peak detector which detects and stores on C₁₃ a voltage approximately equal to the amplitude peak of the voltage that appears on C₁₂. Diode D₁ prevents discharge of C₁₃ into C₁₂, thereby more precisely transmitting changes in magnitude of the filter output signal to electronic switch 51. The voltage on capacitor C₁₃ is applied directly to the control terminal of electronic switch 51.
Either one of capacitor C₁₁ or C₁₂ or one of resistors R₁₁ or R₁₂ shall 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, 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 invention.

Claims

Electronic ski binding comprising an electrical switch (7) connecting the electronic circuitry (3) of the binding to the power supply (1) of the binding, and electronic switch control means (9) adapted to control said switch (7) and to be
actuated by a ski boot,
characterized in that the switch is an electronic switch (7) comprised only of stationary parts and the electronic switch control means (9) comprises an oscillator (17) and a filter (19) and enviromentally variable impedance means (23) adapted to shift either the frequency of the oscillator (17) or to shift the frequency response characteristic of the filter (19) due to an external influence of the ski boot.
The binding of claim 1 wherein said control means (9) further includes latch means (21) for maintaining a connection between said power supply and circuitry (3) when said external influence changes.
The binding of claim 1 or 2 wherein said environmentally variable impedance means (23 comprises a capacitor (31) having two conducting plates and an elastic dielectric disposed between said plates and wherein said external influence comprises pressure applied transversely to said plates.
The binding of claim 1 or 2 wherein said environmental variable impedance means comprises a resistor (R₅, R₇) having a resistance dependent upon the pressure applied to said resistor and wherein said external influence comprises pressure applied to said resistor.
The binding of any of claims 1 - 4 further including peak detection means for detecting and storing the peak amplitude of said output signal of said electronic switch control means.