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Патент USA US2403628

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July 9, 1946.
2,403,623
s. L. BEERs
TELEVISION PICKUP CONTROL SYSTEM
Filed April 25, 1944
2 Sheets-Sheet 1
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INVENTOR
¿sans? L. sse/a5'
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July 9, 1946'
G. L BEERs
TELEVISION PICKUP coNTnonsYsTEM
o
_ Filed April 25, 1944
2 Sheets-Sheet 2
à
ATTORNEY.
Patented July 9, 1946-
l 2,403,628
UNITED STATES - PATENT 4oEFlcE
George- L. Beers, Haddonfield, N. J., assìgnor to
Radio Corporation of America, a corporation of
Delaware
Application April 25, 1944, Serial No. 532,579
16 Claims. - (Cl. 178-7.2)
1
This invention relates to 'automatic control
apparatus, and more particularly to control appa
ratus in which a control function is exercised in
accordance with a selected series of values from
which a control actuating value may be derived.
The invention is illustrated as being applied to
The television pickup system selected for pur
poses of illustration is more or less conventional
and comprises a camera 9 (suggested in dotted
.outline) housing a pickup tube I0 shown as be
ing of thel storage type containing a light sensitive
mosaic II and the usual auxiliary electrodes and
electron emitters. These electrodes include the
anode and the cathode for producing a cathode
focusing of a television camera. Automatic
ray b'eam.» The cathode ray beam deflecting
focusing systems, in order to be fully effective,
must insure against the possibility of accidental 10 means or yoke ‘is indicated conventionallyv at I2
and may comprise horizontal and vertical de
focusing on an unimportant portion of the field
flecting
coils for producing a scanning movement
of view, and moreover, itis desirable to provide
of the beam I4 which is directed onto the mosaic
-for selecting the portion ofthe field of view
II to release a signal output therefrom'to a load
whichy in the opinion of a skilled operator, is the
circuit.
The released signal output of the pickup
15
important portion, or the center of interest of
tube I0 isl applied to a preamplifier I5 across a
the ñeld of view when it is _considered as an
load resistor I6 in most conventional devices.
artistic composition. The 'present invention has
After initial amplification and, if desirable or
for its principal aim not only tc prevent in
necessary, additional ampliñcation, the signal is
advertent' focusing on unimportant portions or
objects of the field of view, but to provide a posi 20 transmitted to a line amplifier I1. Reference
numeral I8 indicates a sync signal generator of
tive means whereby a deiinite object or a desired
a novel arrangement. for obtaining automatic
portion of the ñeld of view will be automatically
kept in focus and may be selected at will.
Another important object of the present in
_vention is to provide a control system operable
in response to a selectable control value.
- A further object -of the present invention is to '
provide means in a control system for selecting
a. source of control values.
Still another object of the invention is to pro
vide a novel motor control system fora reversing
motor which will automatically insure operation
conventional form which generates suitable syn
chronizing and blanking signals, in known man
ner, and which is shown as being connected to
« the ray deflecting means I2 by way of conductors
25 and 26 to supply the horizontal and vertical
beam deflection energy. A conductor 29 con-_
nected to the control electrode 3l of the electron
gun 32 of the scanning tube III providesA the re
turn line blanking. The same general types of
signalsl are also applied tothe line amplifier I1
by way of conductors 34. The resulting composite >
sync and picture signal output of the amplifier
in a desired direction.
I1- may be transmitted over any suitable trans
y Still another object of the invention is to pro
vide a novel arrangement for deriving a control 35 mission channel as 35 to a distribution point such ‘
as a radio transmitter.
signal.
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,
The camera Sis equipped in the usual manner
with a lens combination 36 suitable for imaging
is to provide novel means in a television pickup
the scene, indicated conventionally at 38, on the
system for selecting the portion of the iield of
view vfrom which a control signal or series of sig-r 40 mosaic II. The lens combination 36' is or may
`be equipped with the usual iris diaphragm v(not .
nals are to be derived.
'
Still further objects of the invention will become ‘ shown) for stopping down the lens to obtain
greater depth of focus when the televised scene v_
apparent and suggest themselves to those skilled
is well illuminated. A view finder lens combina
in the art to which the invention is directed upon
tion 4I projects an image of the scene 38 through
reading the following specification and claims in
an inclined, half silvered mirror 42 onto a ground
connection with the drawings‘in which:
glass view finder screen 44. It will be understood
Fig. l is a schematic showing of a television
that the scene 38 possesses three dimensions.
`pickup system, including a television camera and
a portion of the focusing equipment of the pres- - Any known means maybe used for parallax cor
,A still further object of the present invention
50 rection between the lens systems. The purpose of
_ ent invention;
,Figs 2 and 3 illustrate additional equipment
which is associated with the focusing equipment
of Fig. 1; and
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_
'
Fig. 4 shows a slight modiñc tion of Figs. l
and 2.
.
.
o
-
' the mirror 42 together with an associated cath
ode ray tube 43 will be described indetail herein
' after.
A rack 46 and pinion 41 connected to the sup
55 port for the lens combinations 36 land 4I pro
3
2,403,628
vide means for focusing the camera upon rotation
of the pinion 41 by a focusing motor 49. Ener
gization of the motor 48 is obtained under con
trol of a derived signal in accordance with the
invention in a manner to be later described.
-Referring now to the equipment for generat
ing a control signal and for the present more
speciñcally to Fig. 2, conductor 5| furnishes hori
zontal sync pulses for control of a sine wave
4
camera tube |8 representative of the chosen area
during one interval of time to the high frequency
response during the-next succeeding interval of
time. The control circuits to be described for
the motor 48 are so arranged that if the motor
is moving the lens in a given direction to bringY it
in focus on the desired area, the high frequency
response in the second time interval lwill be
greater than during the first time interval. Un
ocillator 52 which runs at image line frequency. 10 der this condition, the. control circuits are so ar
A phase shifter 53 of any known type is adjust
ranged that the motor continues to move the lens
able to shift the phase of the output of the oscil
in the same direction. When the high‘ frequency
lator 52.- A phase shift range of approximately
response during the second interval of time is
180° is desirable. One cycle of the output from
less than during the first interval, the control
the oscillator 52 is shown conventionally above l15 circuit will operate to reverse the motor.
the oscillator and the phase shifter. An amplifier
The control signal which is applied to a relay
54 amplifies successive half cycles of the wave
82 to determine direction of rotation of th'e motor
which are passed through a clipper stage 58.
is derived by the apparatus of Fig. 3 of the draw- i
The clipped half wave, indicated at 58, is passed
ings. The higher frequency components of the
through a shaper and amplifier 8| which gives 20 selected portionof the image signal are passed
the half wave approximately the form shown
by a high pass filter“ (Fig. l), and this high
'
'
'
frequency signal is applied to the control elec
Vertical sync pulses from the sync Asignal gen~
trodes 88 and 81 of vacuum tubes 88 and 88_over
erator i8 are applied over a conductor 84 to a
a conductor 88.
'
I
'
sine wave oscillator 66. ‘The output from this 25
In order to set the time intervals of the suc-.
oscillator is passed to a‘phase shifter 81, and the
cessive high frequency response signals, an oscil
equipment following this phase shifter comprising
lator 92 is provided which may operate at any
4an amplifierv 88, a clipper stage 69, and a shaper
desired frequency. This frequency may be de
and amplifier 'Il corresponds in function to the
termined for example by the time required for
equipment following the phase shifter 53. A 30 the focusing motor to move the lens by an amount
A'pulse 12, similar to the _pulse 62, appears in the
which is sufficient to produce a desired change
output of the wave shaper and amplifier 1| but
in the high frequency output of amplifier 18 and
occurs in timed relationship with respect to the
filter 84. If a time intervalof high frequency
vertical sync' pulses supplied from the >sync gen
response comparison is to be 11s of a second, for
erator. A phase shift range of approximately 35 example, the oscillator 82 may be a 10 cycle oscil
180° for the output of the oscillator 88 is also de
lator. The output 84 of the oscillator 82, which', ‘
sirable.
l
if desired, may be of the sine wave form, is
at 82.
The pulses 82 and 12 are combined in- a con
changed to square wave form 88 in a wave shaper
ductor _14 including a coupling condenser 18 to
88. The waves 84 and- 88 are, it will be under
provide an operating bias for the grid 18 of the 40 stood, not shown to scale along the time axis
cathode ray tube 43, and also an operating bias , with respect to the wave 88, for example, which.
for a spot selector amplifier 18 which amplifles
may be several thousand pulses per second.
the image `signal output of the preamplifier I8.
'I‘he square wave output from the wave shaper
The operating biases of both' the cathode ray tube
88 is applied to amplifiers |8| and |82. 'I'he volt
43 and the amplifier 18 are adjustedso that the
age output wave of the amplifier I 8| is applied
combined voltage of the pulses 62 and 12 causes
to the grid 88 of tube 88, and the output voltage
these >pieces of equipment to become operative - of amplifier |82 is applied to the grid 81 of tube
when the pulses coincide in time.
`
88.~ The voltage wave |88 may be considered as
The luminous spot generated in~ the fluorescent
shifted in phase by 180° from the voltage wave
screen 11 of the cathode ray tube 43 by the cath 50 |81 or may be considered` as of reverse polarity.
ode ray beam 18 is thereby shiftable over the`
The tubes 88 and 88 are _so biased that they func
face of the tube and is reñected from the half sil
tion to amplify the signals applied to~ their grids
vered mirror 42 onto the ground glass viewing
over the conductor 88 during one half of each
screen 44. It is preferred that' light'from the
voltage wave. In this way tube 88 is caused to
luminous spot is of low intensity so that it does
function during a desired series of spaced time
notV obliterate any part- of the image of the scene
intervals. ~Tube 88 is, however, caused to func
38. It will be understood that the elements of
' tion on the alternate timeintervals so that tubes
the tube 43 _are provided with the usual operating
88 and 88 are functioning on equal and alternate
and biasing voltage connections (not shown);
time intervals. The difference in phase between
The luminous spot produced by the beam 18 00 voltage waves |88 and |81 can be obtained by the
may be shifted to substantially any point on the
use of an additional stage of amplification in
screen 44 by manipulating the phase shifters 83
either amplifier I8| or |82. Coupling condensers
and 81, and when this is done the spot selector
|88 and |88 supply high frequency response sig
amplifier 18 passes the portion of the image s18
nals from the high pass filter 84 to the grids 88
nal from the preamplifier I8 representing only 05 and 81 of tubes 88 and 88-respectively.
.
this luminous spot. In this manner an identini
A network, comprising a pair of rectifier tubes
able portion of the picture signal appearing in
>| I2 and |I4 supplied from the cyclically operat
the output of the spot selector lamplifier 'I8 may
ing amplifier tubes 88 and 88, serves to rectify the
be selected .by manipulating the two ph'ase shift- ‘ high frequency signals applied to the rectiiiers
ers shown on Fig. 2 of the drawings. The se 70 across resistors IIB and H3. The high frequency
lected- identiñable portion. of the three dimen
signals across resistor H8 are applied to rectiner
sional scene 38 may lie at any point in its depth.
||4. 'I'he rectiñcation >of these signals by the
'I'he motor“ is operated so as to focus the lens
tube H4 causes terminal |28- of resistor H8 to
38 >on; this selected portion of the scene 88 by
become' more negative with respect to terminal
_comparing the high frequency response from, the
i | 8. Likewise the high frequency signalsv applied
2,403,628
5
to rectifier ||2 across resistor | I3 causes terminal-
||1 to become more negative with respect to ter
minal |I6. Thus, it will be seen that the poten
tial between terminals |20 land I |1 may b'eeither
positive or negative depending on the relative
strength of the high frequency signals applied to
6
switch arm |53 of a rotary switch |54. The
switch arm is connected to one terminal of the
‘ operating coil of the polar relay |24. Alternate
contact studs |56 over which the switch arm |53
is stepped are connected toA a suitable power
source of negative polarity indicated at |51. The
contact studs |59 are connected to a suitable
power source of positive polarity indicated by
reference character |_6|. The rotary switch |54
together with its stepping magnet |49 may be oi'
rectiiiers I I2 and I I4.
. ,
, A -resistor I I8 and a condenser ||-9 serve to
average the successive pulses rectified -by the rec- '
tìiiers `I|2 and ||4 so as toy obtain an averaging 10l
any well known construction, such as the usual
eifect. Thus, -the- terminal IIII likewise becomes
telephone minor switch.
'
either positive or negative with respect to ter
From the lforegoing vit win-be obvious that upon Y `
minal I|1 as the relative strength of the high
frequency signals applied to rectiflers ||2 and'` each over travel of the support 46, for example
toward the- left, as viewed in Fig. 1, switch |42 will
I I4 is varied.
.
be opened resulting in de-energization.. of the
The polarity changes appearing at the point
relay |41. When this occurs, the stepping magnet
' IIIl are applied over a conductor I9 to the re
|49 is energized to step the switch arm |53 to the
lay 82. This Arelay is a polar relay so. construct
next -successive ~contact stud, or as `shown in Fig.
ed that its contact tongue or tongues remain in
the position assumed »prior to de-energization. 20 1 by way of illustration, 'onto a contact stud |56
connected- to the negative 'source |51. The posi
‘ Reversal of the position of its contact tongue or
tion of the contact tongues |36 and |31 with the
tongues requires a change in direction in the
polar relay |24A will be reversed to reverse the
current passing through the relay~ operating coil.
direction of rotation of the motor 49. After the ,
The motor 449 is energized from a suitable .
source such as the direct current source I2I, 25.'l motor has operated in a reverse direction for a
leither the motor armature or the' motor ñeld |22,
in this instance the motor armature, being con
period of time, the switch | 42 will be reclosed
resulting in vde-energization of the relay |41 and
nected across the source |2|. A line switch (not
. release of the pawl I5|which will be returned to
tion of the current applied to its operating coil
switching means, operating in response to the sig
its linitial position by a spring |63. The motor
shown) may be employed to 'disconnect'the motor
and relays when the apparatus is idle. To pro 30 49 will continue to operate until the lensl combi
nation 36 brings the image of the scene 38 sub
vide for reversing the direction of rotation of the
stantially into focus on> the light sensitive 'sur
motor, the field |22 is connected to the 'source
face of the mosaic IIof the cathode ray tube I0.
|`2|- through Vthe tongues and contacts of the
While control relays and polar relays employed
polar relay 82 and the tongues and contacts of
another polar relay |24. The relay |24 is also of 35 as reversing switches have been shown, illus-tratively, it will» be understood that electronic`
'the type which requires a reversal in the direc
nals at the terminal III! to control the motor.
before the position of its contact tongues is re
may be employed.v
versed.
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f
These relays are connected as shown ‘so as to 40
serve as reversing switches for the motor 49. A
make contact |26 and a break contact |28 of the
.
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,
.
All of the equipment involved in this system
except the motor 49, the cathode ray tube43,
and the controls for the phase Shifters 53 and 61
which move the pattern on the oscillograph tube
43, may be located at a monitoring control sta
make contact |29 and a break contact |3| are
connected to the other line conductor. The con 45 tion at a point more or less remote from the
camera 9. If so desired, the control for selecting
ductors |33 and |34 are connected to the motor
relay 82 are connected to one conductor, and a
the desired area may be operated by observing
th'e image on a monitoring >image tube (not
ñeld |22 `through >contact tongues |36 and |31
of the relay |24, the stationary contacts of which
are wired in the _manner explained in connection '
shown) Aat a supervisory control point; The
motor for. driving the pinion 41 will usually be
versal of the position of the tongues'of eitherv
the motor 49 to reverse its/direc
tion of rotation. If, however, the position of the
tongues of both relays is reversed, then the motor
will continue to operate in the same direction as 55
located in the camera housing and the control
relay equipment 'may be ¿separately vmounted and
housed.._ It‘will be understood that parts of the
equipment located near the camera 9 lwill prefer
ably be shielded so as to prevent interference with
. with the stationary contacts of the relay 82. Re
i relay Awill cause
will be obvious from an inspection of Fig. l of the
drawings. While relays have been shown, illus
tratively, to accomplish this purpose, it will be
understood that other means may be employed.
To insure operation of the focusing control of
the television signal generating equipment. '
In operation of the automatic control system of
theinvention for focusing the television camera 9
60
on a particular portion of a iield of view or scene
38, the camera. man operating the camera 9
would manipulate -the control of each phase
shifter 53 and 61 until light from the luminous
spot produced by the cathoderay beam 18 is
superimposed on the portion of the image appear
which cooperate mechanically with suitable means .
such as the projections |43 and |44 on a movable 05 ing in the ground glass screen 44 on which the
camera is tofocus. If the equipment is already
part of the support 46 for the lens combinations
in operation, the camera will, before the shift of
36 and 4|. These limit switches are connected
the luminousspot occurs, have been focused on
across the source |_2I in series with the operating
some portion of the scene 38. However. in the
coil of a relay |41 and are opened upon over
event
that the equipment has just been placed in
70
travel of the lens support _46. The break contact.
operation, the camera may be quickly brought to
|48 of the relay 4|41 energlzes the operating coil
the invention so that the camera will be brought
into focus upon starting the system, normally
closed limit switches |4| and |42 are provided
of a stepping magnet |49 when either of the limit
switches I4I or |42 is opened. '_I'he stepping mag
net is provided with a pawl I5| cooperating with
Aa ratchet |52 which intermittently drives the
focus if the camera man observes that the lens
f 36 is moving in a ydirec-tion away from its posi- ,
tion oi f_ocus by momentarily depressing a key
|63 which will cause the direction of movement
2,403,628
7
.
of the lens to be reversed immediately. This is
accomplished by energization of the operating
coil of the stepping magnet |49 to change the
polarity of current iiowin'g through the winding
of the polar relay |24.
.
'
nection to the tubes 88 and 89,may be omitted.
as well as the driving motor and the motor con
trol apparatus. However, it will be understood
that the modified arrangement of Fig. 4 Shows a
system including thespot selecting equipment in
With the area of the scene upon which the
camera. is to focus selected, as stated previously
ment.
the high frequency response representative of this
area during one interval of time is compared to
IA rectifier |80 rectiñes the high frequency out
put representing the picture area Selected in the
addition to the usual studio and console equip
.
the high frequency response during a. succeeding 10 manner described above by operating the phase
interval of time. This is accomplished by the
Shifters 53 and 6l'. The output of the rectifier
biases applied to the grids 86 and 81 of the tubes `
appearing across the load resistor I8! is applied
88 and 89 respectively from the oscillator 92.
to the grid 10 of the oscillograph I3 so that the
The time interval is preferably such that the lens
spot produced by the beam 18 is brightest when
can move between half cycles of the wave from 15 the lens 36 is in focus on the selected spot. Com
this oscillator.~ If it is assumed that the motor - bining the area indicator on the ñnder screen
48 is moving the lens 36 in the direction to bring
with the feature of changing the brightness of
it in focus on the desired area, the high frequency
the spot .serving as the area indicator shows the
response during the second interval will be
camera operator that the particular spot selected
greater vthan during the iir'st interval of time. 20 is in focus while he is observing the entire scene
Under this condition the polarity at the -point
included by the camera.
.
_
|||l is unchanged, and the motor 49 continues
As an alternative a meter |83 either at the
to rotate to move the lens 36 inthe same direc
camera or at a remote point may be used to indi
tion.
'
cate when the camera is in focus on the selected
If- the high frequency response during a suc
ceeding interval of time is less than during a pre
As the sensitivity ofl television pickup tubes is
ceding interval, the polarity at the .point I I0 will
increased, it becomes possi-ble to pick up tele
a reverse causing the polar relay 82 to reverse the
vision images at light levels which are insufficient
motor.. By this arrangement, the lens 36 will
to provide in a conventional view finder an image
move back and forth through a very narrow range ` 30 which is of suñicient brightness to enable the
centered about the position of optimum focus.
- camera. operator to focus the camera on the de
This variation in lens position will not be observ
‘ sired scene by observing the resolution in the vis
able bythe television audience since the loss Vof
ual image. Under these conditions the arrange
high frequency response which it produces may
ment illustrated in Fig. 4 is particularly effective
be very small, for example, less than 10 per cent,
since the variation in brightness of the focus in
and the camera, pickup tube, and amplifier sys
dicating spot or the meter indication depends en
tem can -be designed with materially greater reso
tirely on the signals derived from the pickup tube.
lution capabilities than will -be obtained from the
Any increase in the sensitivity of pickup tubes
area.
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complete television system including the receiver.
therefore automatically provides a corresponding
It is doubtful that a skilled cameraman could
focus a television camera with this degree of ac
Spot.
curacy merely by observing the image of the scene
38 in the ground glass view finder 44.
In the foregoing example it was assumed that
the initial relationship between the high fre
quency signals applied to ampliñer tubes 88 and
increase in sensitivity of the _focus indicating
.
.
Various alterations and modifications- may be
made in the present invention without departing
from the spirit' and scope thereof, and it is de
sired that any and all such modiñcations be con
88 and the motion of the lens was such that either
sidered within the purview of the present inven
tion as> deñned by the hereinafter appended
the lens moved in the direction to bring the de
claims.
sired scene in focus or that the camera operator
l
used the switch |63 to cause the lens to move in
the desired direction. Assuming now that when
Having nowdescribed the invention, what is
-claimed and desired _to be secured by Letters
Patent is the following:
the initial relationship between the high fre
quency signals applied to the amplifier tubes 88
and 89 and the motion of the lens is such that the
scene upon a light responsive area, means for
focusing the scene on a viewing area, means for
lens moves away from the “in focus” position,
the camera operator does not resort to the use of
scene appearing on the viewing area, and _means
1. In a television system, means for focusing a
selecting a desired portion' of the image of said
the switch |63. In this case the lens will move
for causing said focusing means to automatically
to the end of its travel and either the reversing'
bring the desired portion of said scene in focus.
switch |4| or |42 will -be operated to reverse'the
2. In a television system, means for focusing a
direction of lens motion. 'I'he relationship be 00 scene upon a light responsive- area, means for
i tween the Ihigh frequency signals applied to the
focusing the scene on' a viewing area, means for
tubes 88 and 88 and the lens motion will then be
selecting a desired portion of the image of said
such as to bring the lens “in focus” on the de
scene appearing on the viewing area, means for
sired scene.
~
producing signals indicative of said desired por
' Fig. 4'of the drawings indicates a modification
tion of said scene, and means for utilizing said
of the apparatus of Figs. 1' and 2 enabling use of
signals to vary said focusing means.
‘
the oscillograph 83 in conjunction with any usual
3. In a television system, means for focusing
manual focus control to focus the camera ena
a scene upon a light responsive area, means for
selected area of the ñeld of view 38 without ob
selecting a desired portion of said scene, means
serving iine 'detail' in the image projected on the 70 for producing electrical potentials, the relative
. iinder screen 44.
polarities of which are indicative of said desired
The high pass ñlter 84 is the same as that'
portion of said scene, and means for utilizing said
shown lon Fig. l of the drawings; When lens 36
potentials to vary said focusing means.
is tovbe moved manually in accordance with the
4. In a television system, means for focusing
mode of operation now tube set forth, the con 75 a scene upon a light responsive area. means for
- 9.403.628 .
10
comparison to which said controlling .element is
obtaining a visual image of said scene to indi- ì
cate when said scene is in focus on saidlight
responsive. and means to -actuate the controlling
element in accordance with said characteristic
responsive area, and means for producing another
visual focus indication which can be viewed simul
taneo'usly with said visual image.
_5. In a> television system. means for focusing
whereby. the derived energy is maintained at a
maximum.
.
-. l2. A control system comprising controlled and
controlling elements. mean's for deriving energy
a scene upon a light responsivearea. means for
-. representing the direction of movement of the
‘obtaining a visual image of said scene to indi
>controlled element during- a given time interval,
cate when said scene is in focus on said light
means for deriving energy during a succeeding
10
responsive area. and means for producing an
time interval proportional' to _continued move
~ other visual focus- indication superimposed on
ment, means for comparing the'values of the
said visual image. .
derived energies. means iîor._„¢_iiatainingl a char
acteristic from said comparison toAwhich said
controlling element is responsive.- and means to '
'_ 6. In 4a television system, means ,for focusing '
~ a scene upon a light responsive area, vmeans for
producing a variation in the> resolution of a
actuate the controlling element in accordance
' visual image in response to'a focusing variation,
qwith said characteristic.-
and. additional visual means for producing a
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13. In a television system, means for focusing a
light imagev of a subject upon a light -responsive,
enable resolution of the particular area on saidÍ` 20 area, means for scanning the light responsive
manifestation of the displacement of a particu- _
. lar- area in the >depthof> the scene whereby to
light responsive area.
_
area,
accordance
means~for
with developing
the light intensity
electrical of
energies
the elein
.
7. In a television system. means vfor focusing
a scene on a light _responsive area, means for
producing a variation in the resolution of a vise
ual image in response to focusing variations,
and means for producing an additional indication
. mental areas scanned, means for dividing the
developed electrical energies into increments sep
arated by time intervals, means for comparing
-successive increments to determine 'the difference
in frequency- components ofthe successive in-_
» related to the resolution of the visual image.
crements, and means for -varying the focusing
8. In va television system, means for focusing
. a ~scene on a light responsive area, means f_or
producing a variation in the resolution of a visual 30
image in response to focusing variations, means
for producing a cathode ray stream, means for
producing a visual indication under control of _
said stream, and means whereby said last named
means is responsive to said focusing means.
_
‘9. In _a television system, means for focusing
a scene on a light responsive area, means for
means in accordance with said comparison means.
14. In a television system. power driven means
for focusing alight image of a subiect'upon a light -f
-responsive. area, means for scanning the light
responsive area, means for developing electrical ‘
energies in accordance with the- light intensity of
the elemental areas scanned, means for dividing
the developed electrical energies into increments
separated by time intervals, means for compar- »
ing successive increments to determine occurrence
producing a variation in the resolution of a visual
of a change in frequency components of succes
. image in response to focusing variations, an indi
sive
groups of increments, means for producingxa
40
cating instrument, and mœns for producing a
change in `the indication of said instrument in
response to operation of said focusing means.
10. In a television system. means for focusing
a scene on a light responsive area, means for
producing a- variationin the resolution of a vis#
ual image in response to focusing variations,
means for producing signalsl representing a por
tion of said visual image. said signals varying in
.response to focusing variations, a rectifier for
rectifying said signals, and an indicating` instru-4
ment responsiveto the change in current through
said rectifier which occurs upon' variation of the.
focus.
ll. A control system comprising controlled and ,
controlling elements, means for deriving energy
representing the position of the controlled ele
ment during a given time interval, means for
` --characteristic signal upon occurrence of a change
in frequency components of successive groups.'
and means for varying the focusing 'means in
Y accordance with said characteristic' signal.
v15. In a television system, means for focusing
’ a scene upon alight responsive area, means for
producing electrical eifects, characteristics of
which are indicative of said scena-and means for
, automatically causing said characteristics to vary
in a. desired relationship in response to the actu
ation of said focusing means. _
r16. In ya -television system, means
'
for focusing»
a scene upon a light responsive area, means for
producing electrical potentials the relative polar
- ities of which are indicative of said scene, and
means forv automaticallycausing the polarity >of
- said potentials to vary in a desired relationship
in >response to the actuation of said focusing
deriving energy proportional to a successive posi- ‘
-mean5.
tion during a succeeding time interval, means
Gnomz: L. sanas.
for comparing the values of the derived energies, , 60
means for obtaining a characteristic from said
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