Electrical pulse counters – pulse dividers – or shift registers: c – Applications – Counting based on number of times machine or apparatus operates
Reexamination Certificate
1999-05-10
2001-09-04
Lam, Tuan T. (Department: 2816)
Electrical pulse counters, pulse dividers, or shift registers: c
Applications
Counting based on number of times machine or apparatus operates
C377S016000, C377S030000, C128S200140
Reexamination Certificate
active
06285731
ABSTRACT:
The present invention relates to a counting device, and more particularly but not exclusively to a counting device for use in a dry powder inhaler.
Counting devices often store important information in the form of a count. In some applications, the corruption of such information may have adverse health or safety implications. It would therefore be desirable to reduce the likelihood of the information stored as a count being corrupted. One potential source of corruption is at the enablement of a counting device. Typically, the count in the counting device will be incremented or decremented by responding to a two-state input signal. Such an input signal is typically provided by a switch which has an on and an off state. When the switch is closed the signal is provided to the counting device which causes it to increment by one.
It would be desirable to prevent the erroneous creation of a signal which activates the counter. Such erroneous signals may arise for example by the switch bouncing so that the counting device is activated several times instead of a single time. Another possible source of an erroneous signal is if the switch is accidentally activated.
It would be desirable to provide a counting device which is less susceptible to errors caused by erroneous input.
Accordingly, the present invention provides a counting device, comprising: an input for receiving an input signal having at least three distinct input states; memory means for storing a count; and means responsive to a predetermined sequence of input states of said input signal to vary said count, wherein said predetermined sequence includes the at least three input states.
Preferably, the said means responsive to a predetermined sequence of input states comprises a state machine responsive to the predetermined sequence to vary the count by one.
Preferably, the memory means comprises a BCD counter.
REFERENCES:
patent: 4878136 (1989-10-01), Sarraf et al.
patent: 5593390 (1997-01-01), Castellano et al.
patent: 6142146 (2000-11-01), Abrams et al.
Marnfeldt Goran
Theobald Stephen
Astra Aktiebolag
Fish & Richardson P.C.
Lam Tuan T.
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