Motor vehicles – With means for promoting safety of vehicle – its occupant or... – Responsive to sensing of acceleration – deceleration – or tilt...
Reexamination Certificate
1999-10-05
2001-04-03
Dickson, Paul N. (Department: 3618)
Motor vehicles
With means for promoting safety of vehicle, its occupant or...
Responsive to sensing of acceleration, deceleration, or tilt...
C280S735000, C701S045000, C307S010100, C340S436000
Reexamination Certificate
active
06209674
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to an arrangement for controlling at least one predetermined function which can be transmitted by at least one transmission apparatus to at least one receiver apparatus via a serial data bus.
For the transmission of predetermined functions via a data bus in arrangements of this kind it is often desirable to trigger said functions with a high degree of reliability only if the appropriate message has indeed been transmitted via the data bus. In order to achieve this, DE-OS 196 15 293 utilizes a separation between normal messages, transmitted with a low amplitude, and critical, safety-relevant messages which are transmitted with a higher amplitude. However, at the receiver end the critical function is then triggered immediately by reception of the critical message of high amplitude. Thus, even though a separation is thus realized between non-critical and critical messages, no additional protection is offered against accidental triggering of the critical function at the receiver end, for example due to faults in the receiver.
SUMMARY OF THE INVENTION
It is an object of the invention to improve an arrangement of the kind set forth in such a manner that improved protection against unintentional triggering of the predetermined function is achieved in the receiver, said protection also being effective in the case of transmission errors or faults in the receiver.
This object is achieved according to the invention in that for the control of a predetermined function the transmission apparatus despatches an associated, predetermined data message on the serial data bus and adjusts a transmission parameter of the data bus to a predetermined value, and in that the receiver apparatus triggers the predetermined function only if the predetermined data message appears on the data bus with the predetermined transmission parameter.
When the transmitter is to trigger a safety-critical, predetermined message, the transmitter thus despatches on the one hand an appropriate predetermined data message on the serial data bus. In order to achieve additional safety during transmission as well as during reception, the transmitter additionally adjusts a predetermined transmission parameter of the data bus to a predetermined value. This parameter may concern, for example the speed of the message transmission, the signal amplitude, the amount of offset, or the like.
The predetermined function is triggered in the receiver apparatus only if both the predetermined data message appears on the data bus and the data message is transmitted with the predetermined transmission parameter. Thus, both conditions must be satisfied at the same time; otherwise the predetermined safety-critical function will not be triggered. This offers increased protection against unintentional activation of the predetermined function, because both conditions must be satisfied. The predetermined function is not yet triggered either, for example in the case of incorrect recognition of a data message as a predetermined data message. Unintentional triggering of the predetermined function by failure of a component assembly, for example also in the receiver, is also precluded.
An embodiment of the invention as disclosed in claim
2
is provided with two sensors which generate trigger signals independently of one another, which trigger signals independently activate the predetermined data message and the adjustment of the predetermined transmission parameter of the data bus to the predetermined value. An additional redundancy is thus also realized at the transmission end. An arrangement of this kind can be advantageously used, for example for the ignition of airbags in vehicles.
Further embodiments of the invention as disclosed in the claims
3
and
4
enable simple adjustment and measurement of the predetermined transmission parameter of the serial data bus. An arrangement for adjustment and measurement of a transmission speed on a serial data bus is known per se, for example from DE-OS 197 04 884. Such an arrangement can be advantageously used for the arrangement according to the invention.
The further embodiment of the invention which is defined in claim
6
offers a further advantageous possibility for adjustment of the transmission parameter. The redundancy is then achieved by adjustment of the transmission parameter of the serial data bus by selection of a different polarity of the pulses on the data bus.
The claims
8
and
9
disclose further advantageous embodiments of the invention in which simplicity of construction can be combined with the described protection against unintentional triggering of the predetermined function.
An embodiment of the invention will be described in detail hereinafter, by way of example, with reference to the drawing.
REFERENCES:
patent: 5718452 (1998-02-01), Vogt
patent: 5760489 (1998-06-01), Davis et al.
patent: 5964816 (1999-10-01), Kincaid
patent: 6070114 (2000-05-01), Fendt et al.
patent: 6097761 (2000-08-01), Buhring et al.
patent: 196 16 293 (1996-04-01), None
Biren Steven R.
Dickson Paul N.
U.S. Philips Corporation
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