U.S. patent number 3,846,784 [Application Number 05/357,719] was granted by the patent office on 1974-11-05 for electronic digital displays.
Invention is credited to Clive Marles Sinclair.
United States Patent |
3,846,784 |
Sinclair |
November 5, 1974 |
ELECTRONIC DIGITAL DISPLAYS
Abstract
A digital display device for displaying a plurality of
alphanumeric characters from a single electronic display unit in
which the single unit is reciprocated at a predetermined frequency
through a given distance and the unit is energized to emit an
alphanumeric character display at synchronized positions during its
swing between extreme positions so that the complete display of
alphanumeric characters appears without the eye being able to
detect the motion of the single display unit.
Inventors: |
Sinclair; Clive Marles
(Cambridge, EN) |
Family
ID: |
10203018 |
Appl.
No.: |
05/357,719 |
Filed: |
May 7, 1973 |
Foreign Application Priority Data
|
|
|
|
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May 22, 1972 [GB] |
|
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23893/72 |
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Current U.S.
Class: |
345/31;
340/815.53 |
Current CPC
Class: |
G09F
9/37 (20130101); G09G 3/04 (20130101) |
Current International
Class: |
G09F
9/37 (20060101); G09G 3/04 (20060101); G09f
009/32 () |
Field of
Search: |
;340/24,49,324R,378R,373,336 ;178/7.6 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Caldwell; John W.
Assistant Examiner: Curtis; Marshall M.
Attorney, Agent or Firm: Young & Thompson
Claims
What I claim and desire to secure by Letters Patent is:
1. A digital display apparatus for displaying a plurality of
alphanumeric characters including: a single electronic display unit
having a plurality of individual segments which can be separately
illuminated; an arm carrying the electronic display unit at one end
thereof; means for mounting said arm so that the end of the arm
carrying the display unit can be made to reciprocate through a
given arc of a circle; means defining a plurality of spaced
positions along the arc of the circle at which the required
sequence of alphanumeric characters can be displayed from the
single display unit; display unit reciprocating means energized at
a given frequency to cause a given periodicity of reciprocation to
the end of the arm carrying the display unit; means for energizing
the appropriate individual segments of the display unit at precise
moments as the unit passes each of the spaced positions during each
reciprocation, said display unit energizing means being
synchronized with the reciprocation of the arm so that the
positions of display are identical from one reciprocation to the
next, whereby a series of alphanumeric characters are continuously
visible due to persistance of vision.
2. A digital display apparatus according to claim 1, wherein the
means for reciprocating said display unit comprises: a U-shaped
component made of a springy material, to one extremity of which is
attached the arm; an adjustable counterweight attached to the other
end of the U-shaped component; resilient pads for lightly gripping
the U-shaped component at a point about the base of the U; a fixed
electro-magnet; and a cooperating pole piece attached to one arm of
the U-shaped component for exciting the U-shaped component into
oscillation in the manner of a tuning fork by the interaction of
the electro-magnet and its associated pole piece.
3. A digital display device according to claim 2, wherein the
adjustable counter weight means comprises a threaded rod and a nut,
the nut being threadably engaged on the rod such that the nut may
be screwed in either direction along the rod.
4. A digital display apparatus according to claim 1, wherein said
arm, carrying the display unit at one end, is formed integrally
with a first arm of a pair of lever arms, a pivot point located on
the casing of the display device and arranged substantially
centrally of the pair of lever arms whereby the arms can
individually pivot about said pivot point in the manner of a pair
of scissors, a counterweight being attached to an end of the other
arm which does not carry the display unit.
5. A digital display device according to claim 4, including a
solenoid fixed to the casing of the display; a spring attached at
its outer ends to the two lever arms and at its centre to the
casing of the display; and two pole pieces secured to the
respective arms, the pole pieces being associated with the solenoid
such that when the solenoid is energized, the pole pieces are
attracted into opposite ends of the solenoid thus moving the arms
closer together.
6. A digital display apparatus according to claim 1, wherein the
means for causing a plurality of discrete alphanumeric displays to
be emitted from said display unit at precise positions along the
arc over which the display unit reciprocates comprises: an
oscillator providing a constant frequency to drive the display unit
reciprocating means; a synchronizing circuit driven from the
display oscillator; means for generating electrical signals
representing the required sequence of alphanumeric characters to be
displayed; means for switching on and off said generated signals in
synchronism with the reciprocation of the display unit whereby the
required sequence of alphanumeric characters is displayed over a
complete swing of the display unit from one extreme position to the
other.
7. A digital display apparatus according to claim 6, additionally
including means for generating a feedback signal proportional to
the position of the display unit in order to firstly decrease the
frequency of the output signals to the display unit as the display
unit approaches the extreme positions of its swing, and secondly,
to increase the frequency of the output signals as the display unit
approaches the mean position of its swing, whereby a substantially
equi-spaced alphanumeric display can be obtained.
8. A digital display apparatus according to claim 1, comprising: a
first oscillator; an electro-magnet energized by said oscillator; a
pole piece located on said arm and electro-magnetically associated
with said electro-magnet for driving said arm in synchronism with
the frequency of the oscillator; a calculator inegrator circuit in
which the alphanumeric sequence to be displayed is calculated; a
segment drive circuit cntrolled from the calculator integrator
circuit to enable the correct segments of the display unit to be
energized according to each alphanumeric character to be displayed;
a second oscillator controlling the calculator integrator circuit;
and a synchronizing circuit controlled from the first oscillator
for ensuring synchronous running between the two oscillators.
9. A digital display apparatus according to claim 8, additionally
including: a flyback blanking circuit controlled from said first
oscillator; a gate circuit controlled from the flyback blanking
circuit, said gate circuit passing the output from the calculator
integrator circuit when unblocked; and a monostable driver circuit
connected between said gate circuit and the display unit, whereby
the dispaly unit is not energized during the return movement of the
reciprocating arm, due to the gate being blocked.
10. A digital display apparatus according to claim 8, additionally
including a synchronization gate located between a first output of
the calculator integrator circuit and the synchronizing circuit,
whereby only the first displayed alphanumeric character controls
the synchronization of the calculator integrator through the second
oscillator with the first oscillator.
11. A digital display apparatus according to claim 8, wherein said
second oscillator is also controlled from the position of the
display unit through electro-magnetic coupling means, whereby the
frequency of the output signals to the display unit is decreased as
the display unit approaches the extreme positions of its swing and
increased in the mean position of its swing, so as to produce a
substantially equi-spaced alphanumeric display.
Description
The present invention relates to electronic digital displays.
Equipment which displays information electronically is widely known
and used, and there is a demand for electronic components which
accept electrical signals and display either letters or numbers. An
electronic calculator of known type contains eight such components
each capable of displaying any of the digits from 0 to 9. Each
display unit consists of a seven bar arrangement, the seven
individual bars being separately illuminated and arranged in the
shape of a square eight. With this arrangement the calculator is
able to display any eight figure number. In addition, this type of
display unit can be easily adapted to display letters as well as
numbers.
However, the above described alphanumeric or numeric display
devices are relatively expensive especially when one needs six or
more in order to achieve the desired digital display.
It is therefore an object of the present invention to reduce this
expense by utilizing only a single display device in order to
obtain a display of a plurality of digits.
According to the present invention there is provided a digital
display device capable of displaying a plurality of numbers and/or
letters including a single electronic digital display unit, means
for reciprocating said unit at a predetermined frequency through a
given distance and means for causing a plurality of discrete
electronic displays to be emitted from said display unit at precise
positions in the swing of the unit from one extreme position to the
other.
Preferably in one form the means for reciprocating said display
unit includes a U-shaped piece of springy material to one extremity
of which is attached an arm on the end of which the display device
is mounted, and to the other extremity of which is attached
adjustable counter weight means. Said counter weight means may
comprise a threaded rod upon which a nut is threadably engaged such
that it may be screwed in either direction along the threaded rod.
Means may be provided for the aforesaid assembly to be lightly
gripped in resilient pads at the base of the U and excited into
oscillation in the manner of a tuning fork by the interaction of
the field of an electro-magnet with a pole piece attached to one
arm of the U.
Preferably in another form the means for reciprocating said display
unit includes two lever arms pivotally attached one to the other at
about their centres in the manner of a pair of scissors, the pivot
point being fixedly attached to the casing of the display. The
digital display device and the counterweight may be mounted on
respective ends of the two lever arms. Between the other ends of
the lever arms and the pivot point there may be mounted firstly a
spring fixed at its outer ends to the two lever arms and at its
centre to the instrument case and acting so as to maintain the
adjacent lever arms at an appropriate angle one to another and
secondly a solenoid associated with two pole pieces each being
attached to one of the lever arms such that when the adjacent lever
arms move closer to one another the pole pieces move further into
the solenoid.
Preferably the means for causing a plurality of discrete electronic
displays to be emitted from said display unit at precise positions
in the swing of the unit comprises a synchronizing circuit driven
from a display oscillator and controlling the phase and frequency
of the clock oscillator driving the calculator logic.
Preferably means are provided to speed up and slow down the clock
oscillator by detection of the display digit position, this control
ensuring even spacing of the displayed digits in spite of the
sinusoidal variation of the digit velocity.
The present invention will now be described in greater detail by
way of example with reference to the accompanying drawings,
wherein:
FIG. 1 shows a front elevation of one preferred form of the
mechanical arrangement of the display according to the present
invention;
FIG. 2 is a section along the line I--I of FIG. 1;
FIG. 3 shows a front elevation of the mechanical arrangement of a
second preferred form of the display according to the present
invention;
FIG. 4 shows in functional block diagrammatic form the driving
circuitry for the displays of FIGS. 1 to 3; and
FIG. 5 shows some of the waveforms relating to FIG. 4.
Referring to FIG. 1 the mechanical arrangement of a first form of
the display according to the present invention comprises a one
digit electronic display 21 mounted on the end of an arm 23, the
arm 23 being mounted in the end of one arm of a U shaped spring
metal component 24 in the other end of which is fixed a threaded
rod 25 which carries an adjustable nut 26. The U-shaped component
24 is held between resilient pads 33 and 34, these pads being
lightly held by blocks 31 and 32 which blocks are fixed in a
mounting block 35 which in turn is fixed to the instrument casing
(not shown). The mounting of the U-shaped component 24 is such as
to retain it in position whilst permitting sufficient movement at
the mounting point to enable a torque to be transmitted from one
side of the mounting to the other thus enabling the assembly of the
U component 24 in conjunction with the rod 25 carrying the nut 26
and the arm 23 carrying the digit display 21 to behave as a tuning
fork.
The arm of the U-shaped component 24 which carries the arm 23 and
the digit electronic display 21, has a pole piece 27 secured
thereto near the extremity of said arm of the U-shaped component
24. A solenoid 29 is mounted on a block 30 which in turn is mounted
on the instrument case (not shown). Associated with the solenoid 29
is a feedback coil 28 which is wound on the same former as the
solenoid winding. The purpose of this feedback coil 28 will be
explained in greater detail hereinafter.
The tuning fork arrangement discussed above is excited into
oscillation at its resonant frequency by the attraction of the pole
piece 27 by the solenoid 29 when energized, said solenoid being
intermittently energized at the resonant frequency in order to
maintain the oscillation of the digit display 21.
Fine gauge wires (not shown) which feed signals to the digit
display 21 are attached to the arm 23 and are connected to the
driving circuits via connection points (not shown) on the mounting
block 35. Further connections are made to the driving solenoid 29
and the feedback coil 28. Adjustment of the nut 26 on the threaded
rod 25 enables the two arms of the "tuning fork" to be balanced,
i.e. the moment about the mounting point due to movement of the
short heavy arm 25 is matched by the moment applied by the long
fine arm 23 and display digit 21.
The sectional view of the assembly of FIG. 1 shown in FIG. 2 makes
clear the arrangement whereby the U component 24 made of a flat
strip of a springy metal is held by the resilient pads 33 and 34
which are clamped between the blocks 31 and 32.
The mechanical arrangement of a second preferred form of the
display according to the present invention is shown in FIG. 3
wherein a resonant mechanical system is comprised by arms 41 and 44
in conjunction with a spring 45.
The arms 41 and 44 are coaxially pivoted on a pivot 42 which pivot
is attached to the instrument casing (not shown). At one end of the
arm 41 is mounted a display digit 40, the adjacent end of arm 44
bearing a counter weight 43. The arms 41 and 44 are held at a
suitable mean angle one to the other by the spring 45 the centre of
the spring 45 being located with respect to the instrument casing
by a resilient peg 46.
The resonant assembly is excited into motion by a solenoid 48
attracting into it pole pieces 47 and 49 which are attached to the
arms 41 and 44 respectively. The solenoid 48 has wound coaxially
with it a position feedback coil 51 and is mounted on the
instrument case by means of a mounting block 50. Fine gauge wires
feed the required signals to the digit display 40 and are led along
the arm 41 towards the pivot point 42 in the region of which they
are terminated at suitable connection pins (now shown).
The operation of the display will now be explained with reference
to the remaining figures of the accompanying drawings whereof FIG.
4 is a functional block diagram and FIG. 5 shows some of the
waveforms appertaining to the blocks of FIG. 4.
In the following description the following components in the two
embodiments of mechanical systems described above have the
following general designation for the sake of simplicity.
The one digit displays 21 and 40 are designated 1.
The seven individual segments of the display 1 are designated
2.
The arms 23 and 41 are designated 3.
The pole pieces 27 and 47/49 are designated 4.
The position feedback coils 28 and 51 are designated 6.
The solenoids 29 and 46 are designated 7.
The digit display 1 is mounted at the end of the arm 3 and
comprises seven segments 2 arranged in the form of a square eight,
these segments being individually illuminated according to the
output from the electronic circuit.
The display driving system of FIG. 4 comprises a display drive
oscillator 8; a calculator oscillator 9; a synchronizing circuit
10; a flyback blanking circuit 11; a gate circuit 12; a monostable
driver circuit 13; a calculator integrated circuit 14, hereinafter
referred to as the calculator chip; a segment driver circuit 15 and
a synchronization gate 16. Timing of circuit operations is
controlled from the free running oscillator 8 which drives the
solenoid 7 at the resonant frequency of the mechanical system of
which the arm 3 is a part, setting the display digit 1 into
oscillatory motion. The segments of the display digit 1 are driven
according to the number to be displayed from the segment outputs of
the calculator chip 14 via the segment driver 15. Whilst which
segments are to be displayed is determined by the calculator
output, illumination of the display is controlled by the state of
the monostable driver 13 which switches the display on at
appropriate instants.
The calculator clock oscillator 9 is synchronized in accordance
with digit position by means of the synchronizer 10 which is fed
the output signal of the driving oscillator 8 as well as a signal
corresponding to output of the first display digit. The function of
the synchronizer 10 is to compare the two aforesaid input signals
and produce an output signal capable of controlling the oscillator
9 to synchronize the output of the first display digit from the
calculator chip 14 with one end position of the display digit 1. A
further control of the calculator clock oscillator 9 is provided by
the digit position feedback winding 6 adjacent to the driving
solenoid 7. The correction applied to the clock oscillator 9 by the
output of the winding 6 serves to speed up and slow down the clock
oscillator 9 to produce an even spacing of the displayed digits in
a manner analogous to the S-correction employed in television
receivers. When the display digit 1 is at the end of its swing it
is moving slowly relative to its speed of movement at the centre of
its swing and thus to produce an even spacing of the digits
throughout the display digit's swing the S-type correction applied
by the winding 6 slows the clock oscillator 9 when the display
digit approaches the end of its swing and speeds up the clock
oscillator 9 when the display digit approaches the centre of its
swing.
In order to stop the motion of the display digit 1 when a number is
illuminated, i.e., to make the displayed number appear stationary,
the display is lit for a short period only when a digit output from
the calculator indicates the selection of segments corresponding to
a number to be displayed has been made. The calculator digit
outputs drive the short period monostable 13 via the gate 12 which
gate prevents the monostable 13 from driving the display digit 1
when the flyback blanking circuit 11 driven by the oscillator 8
detects flyback of the display digit 1. Thus the display digit 1
displays on the appropriate segments 2 the calculator output during
one half of its cycle of oscillation. The function of the gate 16
is to permit only the first displayed digit pulse to be fed to the
synchronizer 10 so that it does not attempt to re-synchronize the
clock oscillator 9 on receipt of each digit output.
The operation of the circuitry of FIG. 4 will now be further
explained by reference to FIG. 5 wherein waveform (a) shows the
square wave output of the flyback blanking circuit 11 of FIG. 4,
the output level being "high" during the forward displaying stroke
of the display digit and "low" during the return stroke of the
display digit thus preventing the display from lighting up during
the return stroke of the display digit. During the forward stroke
of the display digit, the digit outputs from the calculator chip 14
pass via the gate 12 (opened by the output of the flyback blanking
circuit 11 as described above) to the monostable driver 13 the
output waveform of the gate 12 being illustrated in waveform (b)
which shows the series of digit pulses. To provide the very short
duration pulses required to "stop" the motion of the display digit
the leading edge of each digit pulse triggers the monostable driver
13 this monostable having the required short pulse width and
producing waveform (c).
The waveforms (a), (b) and (c) of FIG. 5 are drawn to a timescale t
which neglects the variation in clock oscillator speed effected by
S-correction. Taking this effect into account the display drive
pulses are plotted against a real time axis T as shown in waveform
(d). This waveform clearly shows their increased frequency towards
the centre of the display, at which point the digit is moving at
its maximum rate. When the display is driven by the waveform (d) of
FIG. 5, the digits appear evenly spaced out.
* * * * *