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Description  |
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This invention relates to equipment for use by speech therapists and the
like in testing, evaluating and modifying the speech habits of those
persons who are considered to have a speech handicap.
Among those extraordinary people who have frequently been neglected in
times past have been those people who exhibited what is commonly called a
speech handicap. This neglect has not always been intentional, because
certainly there have been relatives and close friends, as well as
professional people such as speech pathologists, etc., who have been very
concerned about the welfare of such handicapped persons. But mere
"concern" or "sympathy" by others usually has not been enough to make much
difference in the speech habits of most persons; what has been needed has
been hardware, instruments, programs and other tangible "tools" with which
the handicapped can be helped. In particular, there has long been a dearth
of equipment with which to evaluate a person's handicap with sufficient
accuracy (and speed) so that a therapist could promptly begin constructive
work with the person--without spending a lot of time in unfruitful
exploration. For example, if a child has a handicap such that he
continually stutters, it usually doesn't take an observer very long to
discern this fact. And if that child who once stuttered has been helped to
full speech fluency, it shouldn't take an observer too long to conclude
that the problem has been solved. But, regrettably, there has not really
existed any equipment with which to accurately evaluate performance
somewhere between these two extremes, i.e., equipment which would permit a
clinician to quickly say with assurance that a child is performing 10% or
15% better this week than he did last week. Neither has it been possible
to demonstrate with empirical data that a given therapy program is more
cost effective than another program because the first program repeatedly
provides more improvement at a lower cost. Hence, it is believed that the
absence of any specialized equipment for measuring speech abnormalities in
a scientific manner has contributed to the prolongation of some rather
laborious trial-and-error techniques in speech therapy that should have
been abandoned (or at least drastically modified) long ago.
Too, in order to determine if a person with a speech handicap is being
helped by a particular program of therapy, it is fairly obvious that tests
should first be performed to find out what is the person's beginning level
of speech capability. This initial testing of the degree of a person's
specific speech errors is commonly referred to as establishing a baseline
for the specified speech behavior of the client or "subject". Although it
is so logical that a baseline or beginning point should be established at
the inception of any program of therapy, until recently there were no
widely accepted or standardized procedures which could be used by various
clinicians throughout the country in order to evaluate the degrees of a
person's speech errors. While each so-called expert in speech therapy
usually had his or her preferred test routines and training techniques,
there were essentially no empirical data for hundreds or thousands of
different handicapped persons which might be useful in discovering which
tests or training techniques seemed to be more reliable than others, or
which therapy techniques seemed to be more beneficial than others and to
which students. Hence, the lack of standardized instrumentation for
monitoring the performance of different persons has tended to inhibit
major progress in dealing with many difficulties in human speech.
Another way in which speech therapists have been ill-equipped and hence
ill-prepared to perform a service is that they have not been able to
ascertain within a minimal period of time whether or not a child's speech
difficulty was modifiable. That is, therapists usually have not been able
to tell with only minimal therapy whether a child's speech problem can be
helped (with proper therapy) or whether it is probable that the defect
will never respond to therapy. If the problem is not modifiable, and it is
not promptly diagnosed as such, then a lot of valuable time can be wasted
in trying to train a child to do something which he physically just cannot
do.
While it is believed that the absence of specialized equipment for speech
therapy has been a hinderance to clinicians, it is not meant to suggest
that there have been no tools at all available in the past. Admittedly,
there have been certain items which have been adapted for use in measuring
speech behavior, but which were not originally designed for such tasks and
therefore (in many cases) had characteristics that made them less than
fully satisfactory. For example, most all clinicians have worked at some
time or another with stop watches, finger-actuated mechanical counters,
electric clocks, kitchen timers, metronomes, pencil and paper, etc.; each
of these instruments and tools was initially designed for a use which was
completely unrelated to speech therapy, and often such tools just would
not meet the requirements for efficient speech therapy. For example,
commercially available timers (such as one might find offered in a
department store for household use) do not measure time as precisely or as
accurately as is needed for many types of speech testing, including the
establishment of diadochokinetic rates and vocal-weightedness. The
inaccuracy (and noise) of household timers could of course be avoided by
using reliable stop watches of the type used in competition sporting
events, etc.; but a clinician's activities with a handheld stop watch can
sometimes be distracting to children who are being tested, such that their
test results might not always be valid. In addition, behaviors which are
inaudible cannot be counted if the clinician must watch a clock.
Accordingly, it is an object of this invention to provide an instrument
which is specifically designed for use in testing, evaluating and
modifying the speech of those persons who have been considered to have a
speech handicap.
A significant part of this invention is concerned with a silent clock or
timer which is ideally suited for use by a speech clinician, in that it
can be used to count time "up" from zero (in order to give the clinician a
ready indication of elapsed time since a testing session began), or, by
activation of a suitable switch, the timer may be used to count time
"down" from a preset quantity (such as 5 or 15 minutes). When counting
down, the expiration of the selected time period is usually announced in
either of two ways: visually alone (as with a blinking light), or by the
combination of a short noise from a buzzer together with a blinking light.
Another part of the unit comprises what will be referred to herein as an
automatic percentage computer, which includes decimal counters for
recording the number of correct and incorrect responses by the student
being tested; individual judgment as to correctness is provided by either
the clinician or the student. Two buttons (switches) are provided on the
face of the unit, one of which is pressed when a correct response has been
given and the other being pressed when an incorrect response has been
given. A first decimal counter records only signals generated when the
"correct" button has been pressed; a second decimal counter records
signals which are generated by both the "correct" and "incorrect" buttons,
and a third decimal counter also records signals which are generated by
both the "correct" and "incorrect" buttons, but it is cleared by a
separate switch to enable the recording of the accumulation of all
"correct" and "incorrect" responses when the first and second counters are
reset. A digital display is provided on the face of the instrument to
reveal the number of correct responses and/or the total number of
responses that have been recorded, as well as a separate display for the
accumulation of the total number of responses for some predetermined
number of exercises. An additional readout is connected to circuitry which
automatically divides the number of correct responses by the total number
of responses, after each entry of a response into a memory bank; of
course, this readout constitutes the percentage of correct answers--and it
provides the clinician with an immediate report of performance by the
student.
A third major part of the speech therapy unit constitutes an adjustable
aural speech rate device that produces "beep" tones that are adjustably
spaced to provide an appropriate "pace" for a stuttering student's speech
in order to achieve complete fluency. The device includes not only a
manual control for the rate at which pulse tones are generated, but it
also includes a volume control so that the intensity of a "beep" tone can
be optimized for each individual student. The pulse tones may be projected
into a room through a loudspeaker incorporated into the unit, or privately
provided to a headset worn by the student. This device constitutes a
significant improvement over conventional metronomes, in that it makes it
possible for a plurality of students to be working in the same room (with
one speech therapy unit per student) under the supervision of a single
clinician, and each student may be receiving--through his or her
individual headset--a pulse tone of optimum intensity at an individually
selected rate. While the clinician may be supervising the use of a variety
of therapy programs in the room, neither she nor the students will be
exposed to the confusion that would stem from a plurality of different
"beep" tones being continually broadcast into the room.
While each of the three above-described sub-units of the speech therapy
unit could be operated independently of the other sub-units, when they are
combined in operation they tend to provide a synergistic effect that makes
the unit described herein a significant contribution to the field of
speech therapy. Hence, the unit will be described hereinafter as a
composite unit in which all of the display means, switches, controls,
power supplies, etc., are physically contained in one housing--because
this is the preferred embodiment of the invention, but it should be
understood that fragmenting the various devices into separate housings
would be feasible. Accordingly, the scope of the invention should be
measured only in terms of the claims appended hereto, with such reference
as is appropriate to the specification and the drawings, wherein:
FIG. 1 is a front elevation view of a preferred embodiment of the
invention, showing the various displays, signal buttons, and controls
housed in one unit;
FIG. 2 is the block diagram of a programmable up/down clock, capable of
displaying the time in minutes and hundredths of minutes;
FIG. 3 is a block diagram of an automatic percentage computer with counters
and displays for the correct, total and accumulated number of responses;
FIG. 4 is the block diagram of an adjustable aural speech rate unit of the
speech therapy apparatus;
FIG. 5 is a block diagram of the immediate audio feedback unit of the
speech therapy apparatus;
FIG. 6 is a schematic of the programmable up/down clock and the associated
alarm unit of the speech therapy apparatus; and
FIG. 7 is a schematic of the circuit components for a crystal oscillator,
an automatic percentage computer, an adjustable aural speech rate device
and an immediate audio feedback with audio and visual means of alerting
students.
Referring specifically to FIG. 1, a speech therapy unit 20 is shown with a
face plate 22 which is preferably located such that it is visible by the
operator but not by the person being studied--at least during the early or
"testing" phase of a program of speech therapy. During a later "speech
modification" phase, the unit 20 may well be turned around so that the
student can see the face plate and serve as the operator. For convenience
hereinafter, the term "student" will usually be employed to refer to the
person having a speech handicap, and the term "clinician" will usually
refer to that person who is controlling the testing and/or attempting to
improve a student's speech.
Referring initially to the first of three major subunits of the device 20,
an electric clock 24 is provided at a suitable location on the face 22.
The purpose of this clock 24 is obviously to monitor the passage of time,
and the unit is descriptively labeled accordingly. The clock 24 comprises
a display means including a face or readout means 26 for indicating
minutes and portions thereof. Preferably, the readout means 26 includes a
digital display face which is adapted to indicate minutes as well as
tenths and hundredths of minutes. Two digital display units such as SP 752
displays can be appropriately used in the clock, since they provide a
readily visible and silent means of displaying time.
A time selector means 28 is also provided as part of the clock 24, and it
preferably comprises a digital selector means in which numerals are
displayed on the periphery of a set of wheels, and the wheels are turned
by means of protrusions which are easily engaged by a person's finger. A
switch 160 is provided in a circuit (to be described) which triggers the
transfer of a selected time from the selector means 28 to the readout 26.
The circuit is such that it will always cause the readout 26 to register
the time which is set in the selector means 28 upon manual activation of
the switch 160, regardless of whether the readout 26 was earlier
manifesting a greater or smaller time than the time shown on the face of
the selector means 28. A reset switch 150 is also provided to drive the
readout means 26 to zero. A start/stop switch 100 is provided to make the
connection between a source of power and a time keeping circuit for
energizing said circuit. The switch 100, then, serves to both initiate and
halt the change of time which is manifested by the display means 26.
A switch 108 is electrically connected to the time keeping circuit for
establishing whether the clock is to count time "up" (as from zero) or to
count time "down" from a preselected time (toward zero). In the
"countdown" mode, the time which is manifested by the readout means 26
will eventually reach zero when the clock has run long enough. In order
that the clinician need not continually turn to face the display 26, it is
appropriate that an alarm of some kind be provided to announce that time
has expired. However, there are certain students who might be distracted
by an audible alarm. Accordingly, a switch 38 is preferably provided so
that the operator may select either an audible alarm or strickly a visual
alarm. Visual notification of the expiration of time is preferably given
by a blinking light 40 located at the top of the time monitor unit. In
order that the audible alarm would not unduly interfere with a testing
program which is under way, it is preferred that any sound (such as the
noise made by a buzzer) be relatively short; but to make sure that the
out-of-time notice rendered by said buzzer is not forgotten, it is
preferred that a visual display element (such as the blinking light 40) be
energized at about the same time that the buzzer is energized. In such an
embodiment, the light 40 should blink continually until it is manually
halted by actuation of the "preset" switch 160--which returns the unit to
a ready condition for renewed count-down operation.
As a further means of rendering the time-counting operation "fail safe",
another alarm feature is advantageously built into the unit . . . in order
to prevent the operator from unknowingly pressing the start button 100 for
"countdown" operation without first making sure that the display means 26
is not already at zero. That is, if the operator has failed to program a
desired time period into the clock by pressing the "Preset" button 160,
then the clock would have nothing to count down to; pressing the Start
button 100 would be useless. If the operator was unaware that he had
failed to set the time monitor 24 correctly, he might spend a substantial
period of time before realizing that the display 26 was not changing. To
avoid this potential oversight by an operator, an alarm is given if an
attempt is made to start the clock in a countdown mode when the display 26
is already at zero. Of course, the actual alarm hardware that is used to
provide this result can be essentially the same alarm hardware which is
utilized to alert the operator to the fact that a given period of
time--which was once imparted to the display means 26--has expired.
Referring next to the second major sub-unit of the device 20, a
calculator-type instrument is incorporated in the device to provide an
instantaneous readout concerning the performance of a student. Of course,
in dealing with students having a speech handicap, there is really no
precise way that a student's performance can be mechanically graded--at
least with today's technology. Hence, as a student attempts to repeat a
series of words or read a sentence, etc., it will still be necessary for a
clinician or other person to make a value judgment as to the correctness
of the student's performance. Too, there are many ways in which a student
may be asked to demonstrate his capability of making certain sounds or
vocalizing certain words. For simplicity herein, however, it will probably
be most convenient to speak merely in terms of "test questions" which are
answered either correctly or incorrectly (even at the risk of taking some
liberties with the term "question"). That is, if the student is asked to
say the word "red" and he pronounces it like "wed" then the clinician
would be expected to record that the student has given an incorrect
response--which, of course, is like answering a question with the wrong
answer.
In times past, it has been possible for a clinician to sit in front of a
student with pencil and paper and record the number of "correct" and
"incorrect" responses. And, after a certain period of time, the clinician
could count the various answers and even determine what the percentage of
correct answers has been--with a slide rule or calculator. However, in
speech therapy, it is important not only to listen to a student's
performance but also to observe what the student is doing with his lips,
his tongue, etc. Accordingly, any manual activity which is required on the
part of the clinician that prevents her from devoting full attention to
the student has been a hinderance to accurate analysis of the student's
handicap. Too, any time which is being consumed by the clinician in making
calculations, keeping records, writing down the quantity of responses,
etc. is administrative time that truly is not being spent in helping the
student.
To overcome these difficulties of the past, the calculator unit 50 includes
a first means including a circuit (to be described) and a button or switch
218 for generating an electrical signal in response to an operator's
judgment that the student has answered a test question correctly. A first
memory within the unit receives and stores the quantity of "correct"
signals generated by this first means. A second means including a circuit
(to be described) and a button or switch 200 is provided for generating an
electrical signal in response to an operator's judgment that the student
has answered a test question incorrectly. A second memory is provided in
the unit 50 for recording the quantity of all signals which are generated
by the operator, including both "correct" and "incorrect" signals. A third
memory is provided for recording and accumulating all such signals
generated by the operator for both "correct" and "incorrect" signals, and
it retains such accumulation when the second memory is blanked. A readout
56 is provided to display for the benefit of the operator the quantity of
signals that have been recorded in the first or second memories. To
economize on the number of physical readout components, it is possible to
employ the same readout to render a status report from these two different
memories; and, when this is done, a toggle switch 58 is provided to switch
the readout 56 from connection with the first memory to connection with
the second memory. The operator, then, would be able to exercise her own
judgment as to which of these two quantities she would rather have
displayed at any given time. A reset button 260 is provided for erasing
the first and second memories in order to return the unit to a cleared
condition for recording performance in a subsequent test. In order to
prevent the loss of all stored information about a student's work during a
test session, however, it is preferable that still another memory be
provided which is adpated to provide a cumulative total of all questions
asked. The display 62 is provided to make this third memory's contents
available to the operator. It would usually be cleared only at the
conclusion of a therapy session by actuating the counter clear button 64.
Of course, the electric displays 56, 62 provide a much neater manner of
recording answers than the old fashioned pencil and paper; but actually
they are probably no more accurate than a pencil and paper, and there
might still be a chance of an arithmetical error if the clinician had to
study the displays and then transfer the entries from the displays 56, 62
to a remote calculator. To avoid the possibility of human error (such as
might happen if the clinician transposed a number, etc.), a dividing
circuit is provided to repetitively and automatically divide the number of
"correct" signals recorded in the first memory by the total number of
signals recorded in the second memory. This division is accomplished after
each entry of a signal into the memories, and a display 66 is provided for
indicating in visual form the quotient which is obtained from that
division step. Of course, that quotient will be recognized as being
numerically equal to the percentage of correct answers, i.e., moving the
decimal point two places to the right converts the quotient to a
percentage. Because this percentage is visible to the operator immediately
after each answer has been entered into the instrument, the operator need
not turn his or her attention far away from the student in order to have
an accurate knowledge of the student's performance. Because of this
particular arrangement of on-going information flow to the clinician, she
is now able to monitor and continually evaluate the relative success or
failure of any given therapy technician in terms of student progress.
The signal buttons 100, 218, 200 are clearly shown as being present on the
face of the instrument; but there may well be occasions when an operator's
repetitive arm movement toward the unit 20 might become a distraction to a
student. Hence, it is preferred that a remote control box 68 be provided
with additional buttons or switches mounted thereon--which buttons would
be connected in parallel with the buttons 100, 218, 200 for starting and
stopping the clock, and recording "correct" and "incorrect" answers. The
remote control hand switch also allows the student, once he has been
taught to accurately discriminate between correct and incorrect production
of target behavior, to record his own correct and incorrect responses
without touching the instrument. In this way, childern as young as 6 or 7
years of age may actually conduct much of their own therapy practice
sessions with only minimal supervision, and without risk of damaging the
instrument. It is also possible that the clinician may prefer that the
student have some sort of immediate indication of how each of his
responses was graded. To this end, a pair of indicator lights 70, 72 are
provided on the top of the unit 20 where they may be seen by both the
operator who is scoring a test and the student who is being tested or
trained. Toggle switches 71, 73 are also provided so that the lights can
be switched out of the circuit when their use is not wanted. A color
coordination scheme for the buttons is preferably followed throughout the
unit 20, so that a correct answer is recorded by the operator by pressing
either the green button 218 on the face 22 or the green button 218A on the
remote control device; naturally a green light 70 announces to the student
that his response was deemed to be satisfactory. The "incorrect" button
200 on the unit and the button 200A on the remote control box are
preferably red; and the lens 72 on top of the unit 20 is also red--for
indicating that the student's response was not satisfactory.
While the operation of the switches 100, 218, 200 is essentially silent, it
may be desirable from time to time for a clinician to render some sort of
an auditory feedback signal to the student without interjecting any
particular emotion into the signal. This is made possible with an
auxiliary buzzer (which is preferably somewhat offensive) and a button 74
which can be pressed by the operator to generate the offensive buzzing
noise. In order to accommodate students whose need for correction or whose
sensitivity may be somewhat at variance with other students, a volume
control 76 for this offensive buzzer is provided. By use of a yellow
button 74 and a yellow light 78, the clinician can communicate with the
student in a somewhat formal way, and can--for example-- indicate
disapproval of certain behavior, can remind the student to concentrate on
the subject matter, can signal the passage of an inordinate amount of time
in which to respond, etc. Also, under certain circumstances the student
may progress in therapy to the point where he can utilize the unit 20 all
by himself, and may grade himself on his pronunciation of certain words,
etc. In such a situation, the student may be facing the instrument and
pressing either the "correct" button 218 or the "incorrect" button 200;
and the clinician can be somewhat removed from the location of the
instrument, having only the remote control unit 68 in her possession. If
the student then grades himself in a manner that the clinician does not
agree with, the clinician can indicate her disagreement by actuating the
switch 74A on the remote control box 68, thereby causing the offensive
buzzer to be activated.
The third substantial sub-unit of the instrument 20 includes a speech rate
generator 80, which includes a pulse rate control 82 and a volume control
84. Of course, this portion of the unit is connected to either a
loudspeaker or a headset adapted to be worn by the student, whereby the
pulse tones generated by the unit may serve to pace the student's speech.
A volume control 88 is provided to adjust the volume of the pulse tones.
It is probably easiest for the generator 80 to be simply energized and
operating at all times when the unit 20 is powered, and the volume control
84 is adapted to turn the level of pulse tones down so low that they
cannot be heard, i.e., essentially zero volume.
A microphone jack 86 and a headphone jack 87 are provided in the device 20
to allow the student to monitor his own amplified speech, as well as to
privately hear the pulse tones generated by the unit 80. Too, the headset
makes it possible for a clinician to privately inform the student of an
error (through the use of the IAF button 74) without anyone else in the
room being distracted by her action.
Line power to the instrument 20 is controlled by a toggle switch 90, with
an indicator lamp 92 providing a visual indication that power is applied
to the instrument.
Referring to FIG. 2, there is shown a logic diagram of a presettable
up/down timing apparatus (clock) that displays time in hundredths of
minutes. The clock consists basically of a gate controlling a 100 pulse
per minute signal that activates four series connected decade counters
which simultaneously control displays that give an indication of the time
represented by these four counters.
A start/stop flip-flop 102 has one input terminal connected to a timer
start/stop switch 100 and a second input terminal receiving a 100 Hz
signal from a source (not shown). Starting the clock by momentarily
closing the start/stop switch 100 applies a logic low at this input of
flip-flop 102, thereby sending a signal from the output terminal Q of the
flip-flop that is at a logic high. Similarly, stopping the clock by again
momentarily closing startstop switch 100 changes the input terminal of
flip-flop 102 to a logic low, thereby reversing the signal from the output
terminal Q of the flip-flop to a logic high.
The signal from the output terminal Q of flip-flop 102 is applied to an
input terminal C of a timer reset flip-flop 104. When this signal to input
terminal C changes from logic low to logic high, then an output terminal Q
of flip-flop 104 is logic low, thereby producing the complement of this
signal at an output terminal Q that is put in a logic high state.
The signal from the terminal Q of the reset flip-flop 104 is sent to an
input terminal of a timer pulse NAND gate 106, which has a second input
terminal receiving a 1.66 Hz signal from a source (not shown). Pulse NAND
gate 106 produces a 100 pulse per minute signal at its output terminal
only when the signal from the flip-flop 104 is in a logic high state. The
signal thus generated by pulse NAND gate 106 is applied to a timer up/down
switch 108 that enables a series of four decade counters 110, 120, 130 and
140 to count either up or down. When the operator selects the count up
mode, the up/down switch 108 is set to send the pulse train from NAND gate
106 to the "up" input terminal of the "hundredths" decade counter 110.
Likewise, when the operator selects the count down mode, up/down switch
108 is set to send the pulse train from NAND gate 106 to the "down" input
terminal of the "hundredths" decade counter 110.
In the countup mode, the "hundredths" decade counter 110 adds one for each
pulse received from the NAND gate 106. When the "hundredths" decade
counter 110 has counted nine times in this manner, the next pulse resets
this decade counter to zero and carries one pulse forward to the "tenths"
decade counter 120, causing it to add one. The minutes decade counter 130
and the "tens" decade counter 140 are similarly connected in series when
counting up so that the higher decade counter is pulsed once for every
tenth pulse received by the next lower decade counter.
Prior to operation of the countdown mode, the decade counters 110, 120, 130
and 140 are loaded with a starting time in the form of a binary coded
decimal digit that is preset from a corresponding ten position BCD
complement thumb switch 112, 122, 132 and 142. An operator actuated preset
switch 160 enables loading the decade counters 110, 120, 130 and 140 with
the predetermined value.
When the countdown mode, the pulse train from NAND gate 106 is received at
the "down" input of the "hundredths" decade counter 110. Each pulse to the
counter 110 borrows (or subtracts) once from the previous value in this
counter. When decade counter 110 steps to zero, the next incoming pulse is
unable to borrow from this counter and is sent to the "down" input
terminal of the "tenths" decade counter 120, borrowing one from it and
reloads the counter 110 to enable the subtraction to continue from the
decade counter 110. Thus, the next higher decade counter is pulsed once
every ten times the lower decade counter is pulsed. The minutes decade
counter 130 and the "tens" decade counter 140 are similarly connected when
the clock is in the countdown mode.
In either a countup mode or a countdown mode, a binary coded decimal digit
in the "hundredths" decade counter 110 is displayed as a decimal digit in
digital display 116 by a "hundredths" digital driver 114 which receives
the signal from the "hundredths" decade counter. Similarly, a "tenths"
digital display 126, a minutes digital display 136, and a "tens" digital
display 146 simultaneously display the decimal value of their
corresponding decade counters 120, 130 and 140. Each of the displays 126,
136, and 146 is connected to the corresponding decade counter through
respective digital drivers, i.e., a "tenths" digital driver 124, a minutes
digital driver 134, and a "tens" digital driver 144.
An operator actuated switch 150 enables resetting the decade counters 110,
120, 130 and 140 to zero and shutting off the signal from the NAND gate
106. First, momentarily closing reset switch 150 enables a signal to be
sent through a zero reset inverter 152 that changes its output from a
logic low to a logic high. This signal from the reset inverter 152 is
applied to decade counters 110, 120, 130 and 140, thereby resetting these
counters to zero. Secondly, momentarily closing the reset switch 150
applies a logic low signal to an input of a preset/reset NAND gate 170,
thereby changing the logic low outpt signal to a logic high. This output
signal is applied to the input of a preset/reset inverter 172 which
produces an output signal at a logic low state. This output signal is in
turn applied to an input terminal R of the timer reset flip-flop 104 which
operates to toggle or reset the logic state at the output terminal Q of
this flip-flop. Reversing the logic state at the output terminal Q from
high to low changes the logic state of the signal at the input terminal of
pulse NAND gate 106 from logic high to logic low, thereby terminating the
pulse output from the NAND gate.
Momentarily closing preset switch 160 enables the presettable up/down clock
to perform three functions. The operation of loading decade counters 110,
120, 130 and 140 with a BCD value preset in thumb switches 112, 122, 132
and 142 has already been mentioned. Secondly, closing preset switch 160
applies a signal at a second input terminal of the preset/reset NAND gate
170 that is at a logic low. This provides a logic high signal at the
output terminal of NAND gate 170, and the effect of this signal is the
same as described above in the operation of reset switch 150.
Finally, closing preset switch 160 enables the operator to set a zero alarm
latch 162 that holds a logic output state indicating that some valve has
been loaded into the decade counters. The borrow output terminal of the
"tens" decade counter 140 applies a pulse signal to a second input
terminal of the alarm latch 162, when all decade counters have reached
zero. This signal resets the logic state at the output terminal of the
alarm latch 162. This output is applied to an input terminal T of a zero
alarm one shot 164. The one shot 164 produces an output signal at its
terminal Q that is applied to the input terminal of an alarm 166 signaling
that either a countdown operation has been attempted when all decade
counters are zero, or that the countdown operation has been completed.
Alarm 166 may use either audio or visual means of signaling the operator.
The following example will serve to illustrate the operation of the up/down
clock of FIG. 2. If the operator desires to time a ten minute exercise,
then ten minutes are preset on BCD thumb switches by placing a "1" in BCD
thumb switch 142 and "0's" in BCD thumb switches 112, 122 and 132. These
numbers are loaded into decade counters 110, 120, 130 and 140 by
momentarily closing preset switch 160, and these numbers are
simultaneously displayed in the displays 116, 126, 136 and 146. The
up/down switch 108 is moved to the down position so that the clock is now
ready for operation. Momentarily closing start/stop switch 100 starts the
clock by generating a signal of 100 pulses per minute at the output of
pulse NAND gate 106. The clock begins to count down and simultaneously
displays the remaining time in the counters, continues counting until
either the start/stop switch 100 is again closed, or the decade counters
step to zero to indicate the preset time has expired. When time expires,
all decade counters will show zero and a borrow pulse will set zero alarm
latch 162, thereby signaling the operator through alarm 166 that the ten
minute period has elapsed.
The operation of the clock in counting up is similar to the operation
described above. The operator sets up/down switch 108 in the up position
and has the option of counting up from time zero or some preset time
loaded through BCD thumb switches 112, 122, 132 and 142. The operator
actuates the clock in the same manner by momentarily closing start/stop
switch 100. The clock will continue to run until the operator closes
start/stop switch 100.
Referring to FIG. 3, there is shown a block diagram of a percentage
computer for the computation of the percentage of the correct responses
given by a speech student during the operation of the testing apparatus.
The percentage computer includes means to compute and to display the
percentage of correct responses, means to count both correct and total
response and means to display either the n | | |
