 |
Claims  |
|
|
We claim:
1. A hand-holdable, self-contained, portable stopwatch having a plurality
of different modes of operation for measuring and displaying a plurality
of intervals of time representing the elapsed times a racer has taken to
cover successive predetermined distances, comprising:
time-base means for providing an internal source of timing signals for the
stopwatch;
first operator-actuatable input switch means for generating first input
commands designating start and stop points of the plurality of intervals
of time to be measured;
second operator-actuatable input switch means for generating second input
commands for switching the stopwatch between at least first and second
distinct timing modes of operation;
timing means connected to the time-base means for successively measuring
the duration of each of the plurality of intervals of time designated by
the input commands received from the first input means;
first display means for simultaneously displaying at least a plurality of
multiple-digit values respectively representing the measured duration of
at least two of the plurality of intervals of time;
second display means distinct from the first display means for indicating
when the stopwatch is in its first timing mode when the stopwatch is in
its second timing mode;
third display means distinct from the first display means for displaying at
least one alphanumeric symbol indicating which of the plurality of
intervals of time the stopwatch is currently set up to time, and
wherein said timing means including microprocessor means for controlling
the sequence of automatic operations of the stopwatch in response to input
commands received from the first and second input means, including
automatically operating the display means and providing the first and
second timing modes, with the operation of the first timing mode including
measuring at least a plurality of overlapping intervals of time having a
common start point and different stop points, and with the operation of
the second timing mode including measuring at least a plurality of
successive non-contiguous intervals of time such that the stop point of
any one such interval is separated by an operator-determined length of
time from the start point of the next interval of time if any to be
measured.
2. A stopwatch as in claim 1, wherein:
the first and second input switch means each include momentary-contact
pushbuttons,
the first display means includes four separate numeric displays each having
at least four digits for displaying a measured interval of elapsed time in
minutes, seconds and fractions of a second, and
the second display means includes at least a first multiple character
display which spells out at least a first legend to indicate at least the
timing mode the stopwatch is in.
3. A stopwatch as in claim 2, wherein:
the first, second and third display means are arranged along a generally
planar surface, with the four displays of the first display means being
arranged in individual vertically adjacent horizontal rows, and the second
and third display means being located generally above the four displays of
the first display means, and
the second display means includes a second multiple character display for
spelling out a second legend to indicate a mode of operation the stopwatch
which is distinct from that indicated by the first multiple character
display of the second display means.
4. A stopwatch as in claim 3, further comprising:
a housing having a generally circular outer rim less than three inches in
diameter and a front portion near which the generally planar surface is
disposed, and wherein
the first, second and third display means are located within a centrally
located broad vertically arranged region adjacent to the front portion,
the first and second input switch means each include as its only
operator-actuatable input device its one momentary contact pushbutton, and
the two momentary contact pushbuttons of the first and second input means
are located generally above the four displays of the first display means
and protrude from the outer rim of the housing.
5. A stopwatch as in claim 2, further comprising:
internal battery means for providing power to operate the stopwatch, and
wherein
the timing means includes stand-by mode means for conserving battery power
by keeping the display means off until such time that an input command is
received, said means including monitoring means for periodically checking
the state of the input means to determine if one of the input means is
actuated.
6. A stopwatch as in claim 1, wherein:
the timing means includes memory means for storing digital values
corresponding to the measured durations of the plurality of intervals of
time displayed as multiple-digit values during the first timing mode and
the second timing mode, and means responsive to the duration that at least
one of the pushbuttons of the input switch means is held in an actuated
state for clearing out the stored digital values, and means for
redisplaying previously displayed multiple digit values not currently
displayed by accessing stored digital values in the memory means.
7. A hand-holdable, self-contained, portable timekeeping apparatus for
measuring and displaying at least a first plurality of intervals of
elapsed time, comprising:
time-base means for providing an internal source of timing signals for the
apparatus;
operator-actuatable input means for generating input commands designating
start and stop points of the plurality of intervals of elapsed time to be
measured and displayed during a first mode of operation of the apparatus
and for switching into and out of the first mode of operation;
timing means connected to the time-base means for successively measuring
the duration of each of the intervals of elapsed time designated by the
input commands received from the input means; and
display means for simultaneously displaying a plurality of multiple-digit
values representing at least two of the plurality of intervals of elapsed
time measured by the timing means, the display means including at least a
plurality of separate numeric display fields each for displaying the
plurality of multiple-digit values in terms of minutes, seconds and
fractions of a second, and wherein the timing means includes
microprocessor means for controlling the automatic operation of the
apparatus in response to input commands received from the input means, the
microprocessor means being programmed to provide the first mode of
operation wherein the timing means measures at least a plurality of
overlapping intervals of time having a common start point and different
successive stop points, to pass to the display means an accumulating value
which represents the substantially instantaneous value of each interval of
elapsed time for which a stop point has not yet been identified, and to
cause the display means to display the accumulating value in each one of
the respective numeric display fields, such that the accumulating value is
displayed in a first one of the display fields until such time as the stop
point for the interval of elapsed time associated with the first one of
the display fields is received, at which time the accumulating value is
displayed in a second one of the display fields until such time as the
stop point for the interval of the elapsed time associated with the second
one of the display fields is received.
8. A timekeeping apparatus as in claim 7, wherein:
the display means has four numeric display fields, and the microprocessor
means is further programmed to cause the accumulating value to be
displayed in a third one of the display fields after the stop point for
the interval of elapsed time associated the second one of the display
fields is received, until such time as the stop point for the interval of
elapsed time associated with the third one of the display fields is
received, at which time the accumulating value is displayed in a fourth
one of the display fields until such time as the stop point for the
interval of elapsed time associated with the fourth one of the display
fields is received.
9. A timekeeping apparatus as in claim 7, wherein, during the first mode of
operation, the timing means, in response to a predetermined input command
sequence from the input means, measures at least a second plurality of
overlapping intervals of time having a common second start point and
different successive stop points, and
the display means includes an alphanumeric display field for indicating the
mode of operation of the apparatus and when the display means is
displaying the first plurality of overlapping intervals of time and when
it is displaying the second plurality of overlapping intervals of time.
10. A timekeeping apparatus as in claim 9, wherein:
the timing means includes memory means for storing digital values
corresponding to the measured durations of the first plurality of
intervals of overlapping time and to be measured durations of the second
plurality of intervals of overlapping time, and means for redisplaying
previously displayed multiple digit values corresponding to the stored
values not currently displayed by accessing stored digital values in the
memory means.
11. A timekeeping apparatus as in claim 7, wherein:
the microprocessor means is further programmed to provide a second mode of
operation wherein the timing means measures at least a plurality of
successive non-contiguous intervals of elapsed time such that the stop
point of any one such interval is separated by an operator-determined
length of time from the start point of the next such interval of time if
any to be measured, and to cause the display means to display at least a
plurality of multiple-digit values representing at least two of a
plurality of successive non-contiguous intervals of elapsed time in terms
of minutes, seconds and fractions of a second.
12. A timekeeping apparatus as in claim 11, wherein:
the microprocessor means is further programmed to pass to the display means
in the second mode of operation a current accumulating value which
represents the substantially instantaneous value of the interval of
elapsed time which is then being measured if any and for which a stop
point has not yet been identified, and to cause the display means to
display in the second mode of operation the current accumulating value in
a corresponding one of the respective numeric display fields, with the
current accumulating value being displayed in each respective one of the
display fields after the start point for the associated interval of
elapsed time has been identified and until such time as the stop point for
the interval of elapsed time is received.
13. A timekeeping apparatus as in claim 11, wherein, during the second mode
of operation, the timing control means, in response to a predetermined
input command sequence from the input means, measures at least a second
plurality of successive, non-contiguous intervals of time having a
distinct start point organized such that the stop point of any such
interval is separated by an operator-determined length of time from the
start point of the next such interval of time if any to be measured, and
the display means includes an alphanumeric display field for indicating the
mode of operation of the apparatus and when the display means is
displaying the first plurality of intervals of time and when it is
displaying the second plurality of intervals of time.
14. A method of operating a hand-holdable, self-contained, portable
timekeeping apparatus for measuring and simultaneously displaying a
plurality of intervals of time, comprising the steps of:
(a) providing an internal source of timing signals for the apparatus;
(b) generating input commands in response to operator actuations of input
switch means, which commands designate start and stop points of intervals
of time to be measured and operator selection of mode of operation the
apparatus is to be in;
(c) measuring in a first mode of operation a first plurality of intervals
of elapsed time designated by input commands received from the input
switch means which intervals have a common start point and different stop
points; and
(d) simultaneously displaying a plurality of values representing at least
two of the intervals of elapsed time measured during step (c).
(e) measuring in a second mode of operation a second plurality of intervals
of elapsed time designated by input commands received from the input
switch means which intervals of time are successive and non-contiguous;
and
(f) simultaneously displaying a plurality of values representing at least
two of the intervals of elapsed time measured during step (e).
15. A method as in claim 14, wherein the timekeeping apparatus is a
stopwatch for timing a racing event, and the apparatus includes a
microprocessor means for controlling the automatic operation of the
apparatus with memory means for storing elapsed time values, and the
method further comprises:
(g) storing a digital value in the memory means corresponding to the
measured duration of each of the plurality of intervals of time displayed
in step (d), and
(h) redisplaying, in response to a predetermined operator-actuated input
command sequence, at least a plurality of previously-displayed values of
intervals of elapsed time not currently being displayed by accessing
stored values in the memory means.
16. A method as in claim 14, wherein the internal source of timing signals
includes an oscillator circuit provided with a crystal and having an
adjustable oscillation frequency, further comprising the steps of:
(e) providing an electronic read-out with plural display fields for
carrying out step (d), and a microcomputer electrically connected to the
internal source of timing signals, the input switch means and the
electronic read-out, and
(f) within the microcomputer, dividing the oscillation frequency of the
oscillator circuit by 2.sup.n, where n is a positive integer having a
value of at least 5, to produce a subfrequency signal;
(g) outputting the subfrequency signal through an output port of the
microcomputer, thereby allowing measurement of the adjustable oscillation
frequency by one or more external probes without loading of the oscillator
circuit by the one or more external probes.
17. A method as in claim 14, further comprising the step of:
(h) speeding up the operation of the apparatus during functional check-out
so that the apparatus runs at at least twice its normal speed, whereby the
operation of the apparatus can be visually checked out at accelerated
speed. |
|
 |
|
 |
Claims |
|
|
|
Description |
|
|
BACKGROUND OF THE INVENTION
This invention relates generally to portable, self-contained electronic
timekeeping apparatus and in particular to hand-held electronic
stopwatches for measuring intervals of elapsed time at horse races and the
like.
Many sporting events involve races where the time required for a
participant to cover a specified distance or successive distances is
measured, recorded and displayed. Horse racing is a familiar example.
Often, at race tracks, the elapsed time required for a given horse to
reach the one-quarter mile mark, the one-half mile mark, the
three-quarters mile mark and the one-mile mark are measured using large,
professional timekeeping systems with distributed input stations where an
automatic photocell sensor or a human being indicates when a given horse
has crossed a particular mark corresponding to a given distance. These
times are then recorded and later published in racing forms, where they
are studied by the betting public and horse trainers. It would be
desirable to have a relatively inexpensive, hand-held stopwatch which
members of the betting public and horse trainers could use themselves to
successively measure the elapsed time for these four quarter mile
intervals, as the race was in progress. Furthermore, at smaller horse
farms where expensive electronic equipment for timing a horse as it covers
a race course is not available, it would be extremely useful to have such
a stopwatch device to assist trainers and spectators to measure the
horse's performance and to use for training purposes. In many other
sporting events, such as swimming, relay races at track and field meets,
auto races and the like, it would similarly be useful to be able to
measure and simultaneously display the elapsed times of a particular
swimmer, runner or car over several segments, parts or laps of a race
course.
Also, in training racing horses or members of a track team, a training
session often involves having the racer cover a specified distance (such
as one-quarter mile), then rest for a period of time, then run the
specified distance again and record the elapsed time, and so on and repeat
this process for a total of eight or nine timed intervals. In order to
record the several elapsed times for these successive intervals using a
conventional stopwatch, it is necessary for the trainer to manually write
down the times in a notebook or the like. Recently, a hand-held electronic
stopwatch with a single multiple-digit display for measuring two
successive back-to-back time periods has become available. This stopwatch
requires the user to push a few buttons to recall the first elapsed time
which was stored, which is inconvenient and cumbersome. It would be much
more useful and convenient to have a stopwatch which could successively
measure and record several of the elapsed times required to cover the
successive distances without having to push several buttons to recall each
of them. It would also be very useful to provide a stopwatch which would
simultaneously display several such elapsed times for comparison purposes.
It would also be most useful for trainers and race spectators to have a
stopwatch which could provide both of the modes of operation described
above and do so interchangeably, simply by pushing one button once or at
most a few times. Furthermore, it would be helpful for the stopwatch to
indicate in a simple manner the mode it is in and the step in a sequence
of steps for measuring multiple intervals of time it is at.
It is the primary object of the present invention to provide a hand-held,
self-contained portable stopwatch which can fulfill the foregoing needs.
Another object is to provide a hand-held stopwatch which has a plurality
of multiple-digit displays and different modes of operation for measuring
multiple intervals of time representing the elapsed times a racer has
taken to cover successive predetermined distances. It is another object of
the present invention to provide a stopwatch of the foregoing type which
has a minimum number of operator controls, and which has additional
displays that make the stopwatch easy to understand and operate correctly
and efficiently.
SUMMARY OF THE INVENTION
In light of the foregoing needs and objects, there is provided according to
one aspect of the present invention a hand-holdable, self-contained
portable stopwatch having a plurality of different modes of operation for
measuring and displaying a plurality of intervals of time representing the
elapsed times a racer has taken to cover successive predetermined
distances. The number of intervals of time which are displayed may be as
small as two. The number of intervals of time which may be measured,
either simultaneously or sequentially, may be as small as two, and may be
as many as sixteen, or more if desired. The stopwatch is comprised of:
time-base means, such as a conventional crystal oscillator circuit, for
providing an internal source of timing signals for the stopwatch; first
operator-actuatable switch means, such as a momentary contact pushbutton,
for generating first input commands designating start and stop points of
the plurality of intervals of time to be measured; and second
operator-actuatable input switch means, such as another momentary contact
pushbutton, for generating second input commands for switching the
stopwatch between at least first and second distinct timing modes of
operation. The stopwatch is further comprised of: timing means connected
to the time-base means for successively measuring the duration of each of
the plurality of intervals of time designated by the input commands
received from the first input means; first display means, such as two or
more multiple-digit LCD read-outs, for simultaneously displaying at least
a plurality of multiple-digit values respectively representing the
measured duration of at least two, and preferably four, intervals of time;
second display means, such as one or more alphabetic LCD read-outs
distinct from the first display means, for indicating when the stopwatch
is in its first timing mode and when the stopwatch is in its second timing
mode; and a third display means distinct from the first display means for
displaying at least one symbol or character, such as a letter or number,
indicating which of the plurality of intervals of time the stopwatch is
currently set up to time.
The timing means of the stopwatch preferably includes microprocessor means
for controlling the sequence of automatic operations of the stopwatch in
response to the input commands received from the first and second input
means, including automatically operating the three display means and
providing the first and second timing modes. The operation of the first
timing mode includes measuring at least a plurality of overlapping
intervals of time having a common start point and different stop points.
The operation of the second timing mode includes measuring at least a
plurality of successive non-contiguous intervals of time such that the
stop point of any one such interval is separated by an operator-determined
length of time from the start point of the next interval of time, if any,
to be measured.
According to a second, broader aspect of the present invention, there is
provided a hand-holdable, self-contained portable timekeeping apparatus
for measuring and displaying a plurality of intervals of elapsed time
comprising: time-base means for providing an internal source of timing
signals for the apparatus; operator-actuatable input means for generating
input commands designating start and stop points of the plurality of
intervals of elapsed time to be measured and displayed and for switching
into and out of a first mode of operation of the apparatus; timing means
connecting to the time-base means for successively measuring the duration
of each of the intervals of elapsed time designated by the input commands
received from the input means; and display means for simultaneously
displaying a plurality of multiple-digit values representing at least two
of the plurality of intervals of elapsed time measured and displayed by
the apparatus. The timekeeping apparatus preferably includes
microprocessor means for controlling the automatic operation of the
apparatus in response to input commands received from the input means. The
microprocessor means may be programmed to provide a first mode of
operation wherein the timing control means measures at least a plurality
of the overlapping intervals of time having a common start point and
different successive stop points. Alternatively, the microprocessor means
may be programmed to provide a first mode of operation wherein the timing
means measures at least a first plurality of successive non-contiguous
intervals of elapsed time such that the stop point of any one such
interval is separated by an operator-determined length of time from the
start point of the next such interval of time, if any, to be measured.
Clearly, the microprocessor means, if it has sufficient memory space, may
be programmed to provide both such modes of operation.
According to a third aspect of the present invention, there is provided a
method of operating a hand-holdable, self-contained portable timekeeping
apparatus for measuring and displaying a plurality of intervals of time,
comprising the steps of: (a) providing an internal source of timing
signals for the apparatus; (b) generating input commands in response to
operator actuations of input switch means, which commands designate start
and stop points of a plurality of intervals of time to be measured and
operator selections as to the mode of operation the apparatus is to be in;
(c) successively measuring the duration of each of the intervals of
elapsed time designated by input commands received from the input switch
means; and (d) simultaneously displaying a plurality of values
representing at least two of the plurality of intervals of elapsed time
measured during step (c).
These and other aspects, objects and advantages of the present invention
will be more fully understood by reference to the following detailed
description taken in conjunction with the various figures and appended
claims.
BRIEF DESCRIPTION OF THE DRAWINGS
The drawings form an integral part of the description of the preferred
embodiments and are to be read in conjunction therewith. Identical
reference numerals designate like components in the different figures,
where:
FIG. 1 is a front elevational view of the preferred embodiment of the
stopwatch of the present invention, showing the relative location of the
two pushbuttons and the several multiple-digit and multiple-character
display fields of the electronic display;
FIG. 2 is a side-elevational view of the FIG. 1 stopwatch taken along line
2--2 of FIG. 1; and
FIG. 3 is a detailed schematic diagram of the presently preferred internal
circuitry of the FIG. 1 stopwatch which shows the various interconnections
between the microcomputer, discrete components and the several display
fields used therein.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to FIGS. 1 and 2, a microprocessor-based electronic timekeeping
apparatus or stopwatch 20 for measuring multiple intervals of time, such
as the elapsed times of a racer covering successive distances of a
racecourse, is shown. The stopwatch 20 is preferably portable and
self-contained in a small, protective, impact-resistant housing 22 which
may be made of any suitable metal, plastic or other material and which has
a generally circular outer rim 24 less than three inches in diameter and
preferably two or more inches in diameter so that the stopwatch can be
very comfortably held in the operator's hand. A small, conventional
lithium battery (represented by circle 26 shown in phantom) may be
provided inside the housing 22 to power the electronics within the
stopwatch. The stopwatch 20 includes an electronic read-out 30 visible
through a transparent face plate 32 having a truncated oval perimeter 34
corresponding in shape to the opening in the front portion 36 of the
housing 22. As best shown in FIG. 2, the housing may also include a rear
portion 38 sealingly engaged or otherwise tightly connected in
conventional fashion to front portion 36 to form the housing 22.
The stopwatch 20 also includes a plurality of conventional
operator-actuatable switch means, such as momentary-contact (SPST)
pushbuttons 40 and 42, and a semicircular carrying ring 46 pivotally
attached at mounting bosses 48 to the housing 20. A thin leather strap or
fabric ribbon such as a shoelace may be passed through the ring 46 so that
the stopwatch may be carried by the strap or ribbon, if desired. The input
switches 40 and 42 are shown protruding through the outer rim 24 of the
housing 20, with the first switch or button 40 being disposed at the top
of the rim 24 and the second button 42 being spaced apart slightly from
the first button, but still above most of the display section 30, for
convenient operation by the thumb when held in the right hand. For the
left-handed operation, the second input switch 42 may be disposed in
location 42', indicated in phantom in FIG. 1.
The read-out 30 of the stopwatch 20 is arranged along a generally planar
surface 50 under the transparent protective face plate 32 within a
centrally located, broad, vertically arranged region of the front portion
36 of housing 22. The electronic read-out section 30 includes first
display means or section 60, which includes four multiple-digit displays
62, 64, 66 and 68, which may be provided with sufficient digits, such as
the four shown, to display a measured interval of time in the desired
units of time such as in minutes, seconds, and fractions of a second.
Display 30 also includes a second display means or section 70 which
includes at least one and preferably the three alphabetic displays 72, 74,
and 76 (as shown) which may also be alphanumeric displays, if desired.
Displays 72 and 74 indicate the mode of operation which the stopwatch 20
is in, either "MILE" or "INT." (for the word "interval"). The display 76,
which may read "READY" as shown, indicates the status of the stopwatch, as
will be further explained. The read-out 30 includes a third display means
or section 80, which preferably is an alphabetic, numeric or alphanumeric
display field indicating the specific interval or intervals of time
currently being measured or about to be measured by the stopwatch, as will
be further explained. As shown in FIG. 1, the display section 80 is
preferably comprised of one digit. As those skilled in the art will
appreciate, the displays 60 through 80 may be of any conventional or
suitable type, such as nematic liquid crystal displays of the type
well-known in the wrist-watch and hand-held electronic calculator arts.
The displays 60-80 are conveniently arranged along the broad vertical
stripe or central region of the front portion 36 of the housing 22 so that
none of the display fields will be obscured by portions of the fingers or
hands of the person operating the stopwatch. The display section 60 has
its four separate numeric displays 62-68 arranged in individually,
vertically adjacent horizontal rows. The second display section 70 has its
three alphabetic displays 72-76 similarly arranged in vertically adjacent
horizontal rows. The third display section 80 is shown larger than the
other display fields 62-68 for ease of viewing, since the number displayed
therein relates to more than one of the display fields of display section
70. However, those in the art will appreciate that the specific legends,
symbols, sizes and layout of the display sections 60-80 shown in FIG. 1
are merely exemplary, and that any other suitable arrangement, legends,
and sizes of display may also be utilized without departing from the
broader aspects of the present invention. Display sections 62 through 68
each preferably have digits which are at least one-quarter inch high, for
ease of viewing the elapsed times displayed therein.
FIG. 3 shows a preferred electronic circuit 100 for the electronics used in
stopwatch 20. The circuitry 100 has as its principal component a
single-chip microcomputer system represented by block 102 which includes a
microprocessor 104, main or working memory, such as random access memory
(RAM) 106, and a memory for program and other permanent storage such as
read-only memory (ROM) 108, which may be of the programmable ROM type. One
suitable single-chip microcomputer system is the Hitachi Model HMCS40
Series LCD IV 4-bit single-chip microcomputer system as described in the
Hitachi preliminary product bulletin No. U131, dated July, 1984, pp. 1-46,
which bulletin is hereby incorporated by reference. Any other conventional
or suitable microcomputer system (one or more chips) may be utilized as
microcomputer system 102. Since microprocessor-based timekeeping
instruments such as wristwatches and stopwatches are well known in the
art, a detailed description of the internal operation and construction of
microcomputer systems need not be provided here. However, so that the
description of the present invention may be more easily understood, it is
worth noting that the Hitachi LCD IV chip features 4,096 words of memory
for program storage and the like in ROM 108, with each word containing ten
bits. Its RAM 106 can store up to 256 digits of data, including display
data at four bits per digit. It features internal control circuitry and
drive circuitry for operating a liquid crystal display in static, 1/2 duty
factor, 1/3 duty factor and 1/4 duty factor modes, using up to four common
signal terminals or pins COM1-COM4 and up to 32 segment signal terminals
or pins SEG1-SEG32. It also features thirty-two other input/output (I/O)
lines, an internal timer/event counter, a built-in oscillator for internal
timing functions, and a built-in oscillator for its system clock. It also
employs CMOS circuitry within for low-power consumption which facilitates
longer-lived operation by battery power. It also features a stand-by or
halt mode which uses even less power so that during periods of non-use,
power consumption is minimized. In this powersaving mode, the contents of
the internal RAM 106, all registers, including the carry and status
registers and program counter, are maintained. It operates on a
low-voltage (2.5 volts minimum). Thus, all active hardware functions and
the flexibility needed for programming the functions provided by the
present invention are furnished in the Hitachi LCD IV microcomputer.
The discrete components of circuit 100 shown in FIG. 3 will now be
described. Battery 110, which may be a three-volt lithium battery (such as
a CR2025 or DL2025 battery) provides power to the microcomputer 102 and
the liquid crystal display section 30. A conventional diode 112 of
suitable power-handling capability is used to protect the circuit 100
against accidental reverse polarity installation of the battery 110.
Capacitor 114 provides power supply decoupling and filtering action so
that a more uniform voltage is provided on VCC supply line 116 by battery
110. Capacitor 114 is preferably of the stacked ceramic type with a low
inductance value.
Capacitor 118 and resistor 120 form an RC network which provides a power-on
reset pulse on line 122 to the input of microcomputer 102, which forces
the internal program counter to the reset address. Initially, capacitor
118 is discharged (via the leakage current internal to the capacitor).
When the battery 110 is installed, an instantaneous three-volt signal is
applied to the input, causing the microcomputer 102 to reset. The voltage
on conductor 122 thereafter exponentially decays, which releases the
internal reset command and allows the microprocessor 104 to begin program
execution.
A conventional oscillator circuit 130, comprised of resistors 132 and 134,
fixed capacitor 136, adjustable capacitor 138 and crystal 140 having a
natural oscillation frequency of about 32 KHz is connected to time-base or
oscillator inputs X0 and X1 of the microcomputer 102. The circuit 130
causes the precise desired crystal oscillation frequency to occur, with
resistor 132 providing drive current, resistor 134 providing feedback, and
capacitors 136 and 138 providing reference to ground 142. The capacitor
138 is adjusted while monitoring the test point output 144 from I/O pin
R31 of microcomputer 102. Output R31 is toggled under program control and
is some frequency F.sub.T which is defined by the expression: F.sub.T
=F.sub.O /2.sup.n, where F.sub.0 is the precise frequency of oscillator
circuit 130 and n is some number in the range of 5 to 15. If n equals 15,
for example, then a two-second period time (or one-second toggle time)
square wave would be produced at the test point 144. If the oscillation
frequency F.sub.0 of the oscillator circuit 130 is 32,768 Hz, and n equals
15, then the state of test point 144 would change from low to high (or
vice-versa) once per second. Using this technique to adjust the clock
frequency (by adjusting the setting of capacitor 138) is preferable
because the test equipment used to monitor the frequency at node 144 does
not alter the clock frequency which it is trying to measure. If the probe
connected to the counter being used to measure the frequency at test point
144 were instead placed upon the input X1 of microcomputer 102, the
loading would in fact change the frequency and cause an inaccurate clock
set-up. Thus, use of test point 144 for adjusting the time base of the
microcomputer 102 via adjustments to capacitor 138 is preferred for
setting the internal time-base means of stopwatch 20, namely oscillator
circuit 130, at its desired frequency, which is 32,768 Hz.
The switch 40 is called the Mode switch, and the switch 42 is called the
Start/Stop switch, for reasons which will shortly become plain. Switches
40 and 42 are connected on one side by conductor 148 to ground 142 and on
the other side to I/O pins R00 and R01, respectively. Both of these inputs
pins may be mask-programmed with an internal PMOS pull-up transistor
device, and therefore do not require the usual external pull-up resistor.
Test switches 152 and 154 may be of any conventional type, and may be
optionally be provided to inputs R02 or R03 for testing, debugging and
quality control purposes during manufacture, if desired. Specifically,
microcomputer 102 may be programmed so that switch 152 turns on all of the
LCD segments in order to verify that all segments are indeed working.
Microcomputer 102 may be programmed so that when test switch 154 is
actuated, the stopwatch 20 will run at an accelerated speed, such as four
to sixteen times its normal rate, so that the functional check-out of the
stopwatch can be done in a much shorter period of time. Such a visual
check-out while the watch is running under accelerated conditions may be
performed by a quality control person or by an automatic machine vision
system which has been appropriately programmed, and includes mechanical or
electronic means which simulate a person operating buttons 40 and 42. Test
switches 152 and 154 are normally not accessible once the housing 22 is
assembled.
Resistor 158 is used by the internal system clock of microcomputer 102 and
forms part of the system's internal clock oscillator. A value of 270
kil-ohms yields a nominal system clock frequency of 200 KHz.
In the power-conserving stand-by mode, the display 30 is shut off. This is
accomplished in part by use of a circuit involving the 22 ohm resistor
160. The output R30 is used to provide output pin V3, which is connected
internally through microcomputer 102 to the display 30, with a return path
to ground 142 through the resistor 160. When pin V3 is high, the display
30 does not draw any current.
The display 30 is preferably comprised of a conventional 1/4 duty cycle
multiplexed reflective liquid crystal display (LCD), such as a silver foil
LCD, which is provided with the various display field 62-68, 72-76 and 80,
organized as previously described. The display 30 is driven by multiplexed
signals on pins COM1-COM4 and pins SEG1-SEG32. Computer system 102 allows
the segments and common signals to be separately set, and therefore any
product of a segment signal and common signal can be addressed separately.
Accordingly, 128 display segments (32.times.4=128) can be addressed. The
first display section 60 has four rows of four seven-segment digits
(4.times.4.times.7=112 display segments), leaving sixteen available
addresses to address the remainder of electronic read-out 30. The sixteen
addresses are used to display the legends "MILE," "INT." (interval) and
"READY," and the colons and decimal points used in the display fields
62-68 of the first display section 60. The lines 170-176 each represent
seven conductors and are used to address the right-most, right-center,
left-center and left-most columns of digits in display fields 62 through
68, as shown in FIG. 3. Line 178 is connected to the SEG 29 pin is used to
address both the colons and decimal points of display fields 62 through
68. Conductor 180 represents the two segment signals SEG30 and SEG31,
which are used to address the seven-segment display 80, in conjunction
with the signals COM1-COM4, respectively provided by individual conductors
190-196. As shown in FIG. 3, the legends "MILE," "INT." and "READY" can be
implemented as one segment each. In other words, for the display 72
containing the word "MILE," for example, the rectangle 202 represents one
electrode, such as the lower electrode, while the dashed rectangle 204
represents the other electrode, such as the upper electrode, which is
addressed by signal SEG32 on line 182. Conductors 190', 192', and 194' are
extensions of conductors 190, 192 and 194 with the lower electrodes 202,
206 and 208 disposed therebetween. In a similar fashion, the illustration
of the display 80 will be understood to consist four lower electrodes 210,
212, 214 and 216 respectively connected to conductors 190', 192', 194' and
196. Two upper electrodes (not shown) located with dashed rectangle 218
and connected via lines 180 to segment signals SEG30 and SEG31 are
appropriately positioned above the various lower electrodes 210-216 to
permit the seven segments of display 80 to be individually addressed using
well-known multiplexing techniques.
In this regard, it should be noted that the Hitachi LCD IV microcomputer
automatically executes a conventional one-quarter duty cycle multiplexing
scheme when the segment data is written into appropriate address locations
reserved for this purpose in RAM 106. An internal LCD driver circuit (not
shown) within microcomputer 102 provides the four common signals
COM1-COM4. This completes the description of the hardware aspects of
circuit 100 of FIG. 3. A detailed functional description of the operation
of the stopwatch 20 and microcomputer 102 will now be provided.
The stopwatch 20 has three basic modes of operation: the Off mode, the Mile
mode and the Interval mode. The Off mode employs the stand-by mode
provided by microcomputer system 102 for ultra-low power consumption.
During the Off mode, the display 30 is off and appears blank, and the
contents of RAM 106 are maintained (i.e. not lost). In the Mile mode,
measured elapsed times for four successive time intervals having a common
starting time (which may be called the start point) and different stopping
times (which may be called the stop points) can be simultaneously
displayed. The utility of the simultaneous display of fou | | |
