United States Patent [191
`Bendell et 21.
`
`[11]
`[45]
`
`Patent Number:
`Date of Patent:
`
`4,532,550
`Jul. 30, 1985
`
`[54]
`
`[75]
`
`[73]
`[21]
`[22]
`[51]
`[52]
`
`[5 8l
`
`[56]
`
`EXPOSURE TIME CONTROL FOR A
`SOLID-STATE COLOR CAMERA
`
`Inventors: Sidney L. Bendell; Cydney A.
`Johnson, both of Burlington, N.J.
`
`Assignee: RCA Corporation, Princeton, NJ.
`
`Appl. No.: 575,570
`
`Filed:
`
`Jan. 31, 1984
`
`Int. Cl.3 ............................................. .. H04N 3/14
`US. Cl. .................................. .. 358/213; 358/228;
`358/225
`Field of Search ............. .. 358/209, 211, 212, 213,
`358/214, 215, 216, 217, 225, 227, 228, 102, 113,
`134; 357/30
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`3,303,271 2/1967 Hecker .............................. .. 358/225
`4,161,000 7/1979 Cleveland ......................... .. 358/225
`4,171,529 10/1979 Silberberg et a1. .
`4,280,141 7/1981 McCann et a1. .................. .. 358/213
`4,363,034 12/1982 Grancoin et a1. .
`4,370,677 l/l983 Baldwin et al. ................... .. 358/225
`
`4,399,464 8/1983 Hix et al. . . . . . .
`. . . .. 358/213
`4,427,996 1/1984 Tamura ............................. .. 358/228
`4,489,350 12/1984 Kimura .
`
`FOREIGN PATENT DOCUMENTS
`
`3022786 l/l98l Fed. Rep. of Germany .... .. 358/228
`57717 5/1977 Japan ................................. .. 358/228
`44271 4/1981 Japan ................................. .. 358/213
`
`OTHER PUBLICATIONS
`US. patent application Ser. No. 330,033, ?led Dec. 14,
`1981, (Dischert).
`Primary Examiner—Gene Z. Rubinson
`Assistant Examiner—Robert Lev
`Attorney, Agent, or Firm-Eugene M. Whitacre;
`Lawrence C. Edelman; William H. Meise
`[57]
`ABSTRACT
`A television camera includes a solid-state imager which
`forms a signal representative of the image during an
`integration interval. The integration interval is followed
`by a pull-down interval during which the integrated
`signal is transferred out of the photo-responsive region
`of the solid state imager. A shutter is provided which
`periodically prevents light from falling upon the photo
`responsive region of the imager. The shutter is control
`lable for controlling the integration interval. Thus, by
`effectively adjusting the integration interval special
`effects such as “true” stop motion may be provided
`from a television scene.
`
`21 Claims, 6 Drawing Figures
`
`‘76
`RI ,m
`m __cAIEn
`cl
`MIXER
`A“?
`
`B
`
`H
`
`1v
`smc
`+v
`
`3021*
`
`CONPOSIIE
`COLOR
`SIGNAL
`
`-——-—1
`5
`a
`L 60
`
`PHASE-LOCK
`L00? 0F
`FIG 4
`
`VERI DRIVER
`
`7
`
`VERT
`SAW
`GEN
`
`58
`
`VALEO EX. 1008
`
`

`
`US. Patent Jul. 30, 1985
`
`Sheet 1 of3
`
`4,532,550
`
`2522s
`
`:5;
`
`128 ll!
`
`GM 1.
`
`.255
`
`.02;
`
`0
`
`5E?
`
`mm gm; w -
`
`
`
`.E< moEm S 9k
`
`3% <3
`
`25
`
`.5555
`
`

`
`U.S. Patent
`
`‘Jul. 30,1985
`
`Sheet2of3
`
`4,532,550
`
`2315m_¢m>
`
`
`
`¢u>_za_¢m>
`
`cam)
`
`am
`
`.°=_z°
`m_¢_
`Us
`
`
`
`

`
`U.S. Patent
`
`Jul. 30,1985
`
`Sheet3of3
`
`4,532,550
`
`3
`
`_s:_§
`
`Exam
`
`E35E__q8H
`
`
`,_§%/1mg.5,we52..
`
`2.82.23%5:__E§.;3i
`
`._
`
`_U
`
`
`
` .QoW)?5.”3:55:In:m5.2.;5:2.E2.5,jw8v5:....3,i.».i
`
` :1.5,:4:EV..Qlllul.nnJN.:z_.._§
`
`
`
`
`
`

`
`1
`
`EXPOSURE TIME CONTROL FOR A
`SOLID-STATE COLOR CAMERA
`
`4,532,550
`
`The present invention relates to television cameras
`having exposure time control and, more particularly, to
`solid-state color cameras having a variable apertured
`shutter for varying the exposure time.
`
`5
`
`BACKGROUND OF THE INVENTION
`In a tube-type color camera the effective exposure
`time is l/ 30th of a second, comprised of two interlaced
`?elds of 1/60th of a second each. One of the drawbacks
`in tube-type cameras is that they exhibit low resolution
`when picking up fast moving objects. In the past an
`optical shutter has been evaluated in such cameras to
`shorten the exposure time, however, the results have
`not been impressive due to the lag characteristics of
`tube-type sensors.
`A solid-state camera has zero lag and, therefore, is a
`good sensor for picking up fast moving objects. With
`such a zero lag device it is now feasible to use optical
`shuttering to enhance the dynamic resolution of the
`camera. In a frame transfer (also known as a ?eld-trans
`fer) charge-coupled device it is generally considered to
`be necessary that the imager be optically shuttered
`during the interval (vertical blanking) in which the
`charge accumulated in the imaging area of the device is
`transferred to the storage area of the device. Failure to
`shutter during this period causes vertical image smear,
`most noticeable when picking up scenes containing
`highlights. In a frame transfer CCD having 403 hori
`zontal elements the effective exposure time is l/60th of
`a second due to the method of signal readout. Interpos
`ing a mechanical shutter (rotating wheel) between the
`main camera lens and the prism system eliminated frame
`transfer smear and incidently achieves a limited amount
`of optical shuttering.
`In US. patent application Ser. No. 330,033 ?led on
`Dec. 14, 1981, in the name of R. A. Dischert a solid
`state camera is disclosed which includes a shutter ar
`rangement for controlling the exposure time of the
`camera. In accordance with one aspect of the Dischert
`application, two similar shuttering devices are arranged
`in series such that the combined effective width of the
`shutter blades may be adjusted to improve the resolu
`tion of the moving images. Two shutters are arranged
`coaxially on shafts which are long enough to protrude
`through the camera housing so they are accessible to
`allow relative rotation therebetween. With this arrange
`ment, the light passage between the blades of the shutter
`system can be reduced to a slit to provide “true” stop
`motion of an image during action sequences.
`In accordance with the present invention a shuttering
`system is provided which permits automatic exposure
`time control of a solid-state camera. For example, two
`similar shutters are arranged coaxially. One shutter
`motor is locked to vertical sync while the other shutter
`motor which is also locked to vertical sync is provided
`with a variable phasing control. Variation of the rela
`tive phase of the two shutters changes the effective
`exposure time.
`A variable shutter exposure control permits the cam
`era operator to select different exposure techniques for
`artistic or special-effect purposes. Essentially all televi
`65
`sion cameras have an automatic iris control. Control of
`the iris is normally based on a measurement of the high
`est signal (in the red, green or blue channel) in the cen
`
`2
`tral area of the picture. The iris drive motor is servoed
`in a manner such that constant peak signal level is main
`tained at the camera output. According to this method
`the exposure time control of the shutter is varied manu
`ally and constant output signal is maintained by the
`automatic iris servo. In an alternative method of operat
`ing, the camera system could be run so that the iris is
`positioned in a ?xed position and then servo the expo
`sure time of the shutter to achieve constant camera
`output signal. Such a dual system is analagous to that
`used in modern single lens re?ex ?lm cameras. Such
`systems are referred to as “aperture preferred” or “ex
`posure preferred”.
`
`SUMMARY OF THE INVENTION
`A camera having an image transducing means pro
`vides television signals representative of a scene. The
`image transducing means includes a photosensitive sur
`face for generating signal in response to received radi
`ant energy from a scene. Further, the camera includes
`shutter means arranged to block radiant energy from
`the scene from reaching the photosensitive surface dur
`ing a portion of a television ?eld. The shutter means is
`automatically controllable for varying the portion of
`the a television ?eld during which radiant energy is
`blocked.
`
`BRIEF DESCRIPTION OF THE DRAWING
`In the drawing:
`FIG. 1a illustrates, partially in block diagram form, a
`prior art solid-state camera including a three-port color
`splitting prism and three solid-state imagers;
`FIG. 1b shows a shutter arrangement;
`FIG. 2 shows a timing sequence;
`FIG. 2a illustrates, partially in block diagram form, a
`solid-state camera arrangement in accordance with the
`principles of the present invention;
`FIG. 3 illustrates the details of the dual shutter ar
`rangement in accordance with one embodiment of the
`present invention; and
`FIG. 4 illustrates, partially in block diagram form, a
`circuit for providing the servo control of the dual shut
`ters of the present invention.
`
`DETAILED DESCRIPTION OF THE
`PREFERRED EMBODIMENTS
`In FIG. 1 a prior art solid-state television camera 1 is
`shown. Camera 1 includes a zoom lens 10 with an iris 12
`which is controlled by iris control 14. The lens focuses
`a scene (not shown) onto the surfaces of a blue-respon
`sive solid-state imager 16, a red-responsive image 18 and
`a green-responsive image 20.
`Iris 12 controls the relative amount of light that
`passes through lens 10 by controlling the effective lens
`aperture diameter. When the scene is bright the iris
`contracts to permit less light to pass through and when
`the scene is dimly lighted the iris expands to permit
`more light to come in. Another important feature of the
`iris is to control the depth of ?eld of the scene, i.e., the
`distance between the nearest object of the scene in focus
`and the farthest object in focus. By controlling the iris
`opening manually and controlling the exposure time by
`other means one may enhance the artistic features of a
`television camera.
`A shutter 24 in the form of a notched wheel forming
`two blades is rotated by motor 26 so that the blades
`alternately pass between lens 10 and prism 22 as the
`shutter rotates. Referring to FIG. 1b the details of shut
`
`

`
`3
`ter 24 are shown. The shutter includes two blades 28
`and 30 which are opaque so that the blades shut off light
`to, or shutter, the imagers when interposed in the light
`path. Motor 26 is coupled to a reference signal (not
`shown) for maintaining the shutting off of light by the
`shutter blades in synchronism with the pulldown inter
`val for the imagers. A position sensor 32 which senses
`the angular speed and phase of shutter 24 is coupled to
`the servo loop for controlling the motor for maintaining
`the synchronism of the shutter.
`In order to shutter the imagers during each pulldown
`interval, the shutter has two blades disposed 180° apart
`(it should be noted that the shutter may include less than
`or more than two blades, illustratively, the camera de
`scribed herein will use two blades for reasons of inher
`ent dynamic balance and reduced motor bearing wear).
`Each blade shutters the imager once during each half
`rotation of the shutter or once during each ?eld inter
`val. The approximate angular sector a subtended by
`each of the two blades includes a ?rst angular portion a,
`proportional to 180° in the same ratio as the pull-down
`time tpd to the ?eld interval time tf, plus second angular
`portion (12 representing twice the angular width qb of
`light cone 80 to be cut,
`
`20
`
`25
`
`35
`
`Each of the solid-state imagers 16, 18, 20 may be of
`the CCD frame transfer type (also known as ?eld trans
`fer CCD) which include an “A” register onto which
`light is focused and in the surfaces of which photoelec
`trons are generated. Of course, it should be realized that
`the present invention is not limited to frame-transfer
`CCDs, as other solid-state imagers may be used. The
`photoelectrons are constrained within vertical channels
`on the imager. Vertical motion of the accumulated
`image representative charge is controlled by polyphase
`(e.g., three phase) clock voltages applied to control
`electrodes from clock signal generator 34. After an
`integrating period, the clock signals are activated to
`produce transfer of the electrons into the corresponding
`portions of a “B” register which is free from light in?u
`ence. The accumulated charge which resides under the
`control electrode of the “B” register is clocked line by
`line in parallel from the “B” register to a “C” register,
`from which they are clocked in serial fashion by clock
`signals applied to the clock electrodes from the clock
`signal generator 34. The signals are clocked out of the
`“C” register in serial fashion in response to the poly
`phase “C” clock drive. The clocking signal generator
`34 is coupled to sync signal generator 36 which gener
`ates synchronizing signals used in a television signal.
`The output of the sync signal generator is applied to
`signal processor 38 so as to insert synchronizing, blank
`ing, equalizing and burst signals.
`The output signals from imagers 16, 18 and 20 are
`applied to signal processor 38 which may include, black
`level correction, clamps, shading, gamma correction,
`matrixing circuits and other types of standard signal
`processing. The R, G, B signals are matrixed to Y, I, Q
`and the color representative components are quadra
`ture-modulated onto a subcarrier to form a composite
`signal such as NTSC or PAL.
`One problem to which the invention is directed is that
`of exposure time control. By varying the relative phase
`of two shutters the effective exposure time of the cam
`
`30
`
`4,532,550
`4
`era can be adjusted for providing special effects such as
`“true” stop motion or the like.
`FIG. 2 shows a camera system in accordance with
`the principles of the present invention. In the Figures,
`elements designated with like reference numerals are
`the same or similar items in the various Figures. The
`camera includes a zoom lens 10, iris 12, iris control 14
`and imagers 16, 18 and 20. Prism 22 is used to split
`incoming light into its primary colors for projection
`onto respective imagers 16, 18 and 20. The signal from
`imager 16, 18.and 20 is delivered to signal processor 38
`which provides R, G and B signals to encoder 40 which
`may include a matrix circuit forming the composite
`color signal for use in the standard television receiver.
`Interposed between lens 10 and prism 22 are a pair of
`rotary shutters 42 and 44. Shutter 42 is driven by motor
`46 and shutter 44 by motor 48. Each shutter includes a
`position sensor 50 and 52, respectively, for providing
`speed and phase information to a servo control loop for
`use in controlling the speed and phase of shutters 42 and
`44.
`According to one aspect of the invention the two
`shutters 42 and 44 (FIG. 3) are arranged coaxially but
`may be rotated independently. In this system, shutter 44
`is locked to the vertical sync and shutter 42 which is
`also looked to the vertical sync has a variable phasing
`control for varying the amount of shuttering performed
`by the combined shutter. The action of varying the
`relative phase of the two shutters changes the effective
`exposure time. For example, with exact phase alignment
`of two 70° shutters (70° opaque, 110° transmissive) the
`exposure time for a ?eld is (180°-70°) degrees out of
`180° degrees or 0.0102 seconds. If the shutters are mis
`phased completely (140° opaque, 40° transmissive) the
`effective exposure time is 0.0037 seconds. This gives a
`time exposure range of about 2.8 times. If on the other
`hand, the opaque angle of each shutter blade is equal to
`80° the exposure range would be increased to 5 times.
`Other variations of the included angle may be made to
`change the exposure range. Two servo controls are
`used for controlling the shutters. The servo control for
`controlling the speed and phase of the two shutters will
`be explained with reference to FIGS. 2 and 4. First, the
`servo control for the shutter for maintaining the critical
`pull-down interval will be explained with reference to
`FIG. 4. For shutter 42 which is used for controlling
`light during the ?xed pull-down interval the reference
`signal for the servo loop is derived from the vertical
`blanking pulse, hence switch S2 is placed in the position
`illustrated in FIG. 4. The vertical drive pulse is deliv
`ered to buffer translator 401 which is used for level
`shifting and isolating the servo shutter circuit from the
`vertical drive distribution bus. The buffered vertical
`drive is delivered to pulse shaper 403. The gates of pulse
`shaper 403 are used to generate a narrow negative
`going pulse illustrated as 430 whose positive going edge
`transition is used as a reference time by phase/fre
`quency comparator 405. Switch S2 is positioned as
`shown in FIG. 4 for the servo control of shutter 42.
`Phase/frequency comparator 405 generates an error
`signal to establish and update the shutter motor to a
`constant speed and consistent phase relative to the pull
`down interval. The phase is necessary to position the
`shutter in such a matter that no light falls on the “A”
`register of the CCD when the transfer of the video
`signal is made from the “A” to the “B” register during .
`the vertical interval. This error signal is related to the
`difference in the timing of two pulses, one from pulse
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`

`
`5
`shaper 403 which is a stable reference and another
`which is the feedback pulse from pulse shaper 407.
`Illustratively, phase/frequency detector 405 may be an
`RCA 4046 phase comparator. The output of phase/fre
`quency detector 405 is high when the motor speed is
`low and low when the motor speed is high. When refer
`ence speed is obtained the output is a negative or posi
`tive-going pulse whose duration is related to the phase
`duration between the reference signal and the feedback
`signal. When both the frequency and the phase are
`locked-up the output of the phase/frequency detector is
`an open circuit. Capacitor C19 maintains the average
`DC level while phase/frequency detector 405 is open
`circuited. The time constant of R44 and C19 are such
`that the update signal may be applied directly to buffer
`409. Buffer 409 presents a high impedance to the output
`of the phase/frequency detector 405. The output from
`buffer 409 is deleivered to low pass ?lter 411. Low pass
`?lter 411 has a cutoff frequency in the region of the
`fundamental of the shutter speed to reduce the noise
`applied to the motor at high frequencies. The output
`from low pass ?lter 411 is applied to notch ?lters 413
`and 415 in serial fashion. These outputs which are
`notched at approximately 60 and 120 Hz to keep any
`residue from the update pulses from being directly ap
`plied to the motor, thus aiding in eliminating motor
`jogging and singing. The output from notch ?lter 415 is
`applied to phase compensator 417. Phase compensator
`417 is a phase lead compensator which compensates for
`phase errors effectively damping the mechanical system
`thus providing stability to the servo loop. The output
`from phase compensator 417 is delivered to motor
`driver 419 which in turn drives motor 421 and shutter
`423 (either shutter 42 or shutter 44 of FIG. 2). A posi
`tion sensor 425 is arranged to detect the edge or some
`appropriate part of shutter 423 to provide a signal re
`lated to the speed and phase of the shutter. The output
`from position sensor 425 is delivered to pulse shaper 407
`which provides a squared-up pulse which is the feed
`back pulse to phase/frequency detector 405. Thus, the
`phase-lock loop of FIG. 4 maintains the reference posi
`tion of rotating shutter 423, as established by the posi
`tion sensor, so that the reference position occurs at the
`instant of the reference timing pulse.
`Referring again to FIG. 2 shutter 44 is normally con
`trolled by the signal output from signal processor 38. In
`other words, the phasing of shutter 44 is controlled
`relative to that of shutter 42 to control the exposure
`time of the overall shutter system. In this arrangement,
`switch S2 of PLL 70 (also illustrated by FIG. 4) is
`thrown so that the signal from terminal “A” is deliv
`ered to phase/frequency detector 405. It should be
`noted that for each shutter a separate servo arrange
`ment would be required.
`The material that follows will describe the generation
`of a phase-shifted reference pulse 203 for servo arrange
`ment 70 for control of the second shutter, i.e., shutter
`44. The R, G, B signals from signal processor 38 are
`supplied to a matrix and encoding circuit illustrated as a
`block 40, and also to nonadditive mixer 52 which selects
`the signal of the largest value for delivery to gated
`ampli?er 54. Gated ampli?er 54 selects the signal from
`near the center of the picture for exposure control. That
`is, gated or gain-controlled amp 54 center weights the
`signal from nonadditive mixer 52 for use in controlling
`the exposure of the system. Horizontal and vertical
`synchronizing pulses are delivered to gated ampli?er 54
`for use in selecting the centered value. The output from
`
`40
`
`45
`
`50
`
`55
`
`60
`
`65
`
`4,532,550
`
`20
`
`25
`
`35
`
`6
`gated ampli?er 54 is delivered to video peak detector
`56. In the automatic arrangement, as described now, it is
`assumed that the iris control would be set at some ?xed
`value and that the exposure control would be per
`formed by control of the phasing of the shutters. There
`fore, in this arrangment switch S1 would be switched to
`the automatic position. The signal from video peak
`detector 56 is delivered to vertical saw generator 58
`which provides a variable ramp as a function of the
`magnitude of the video peak. Referring to FIGS. 2b and
`c, FIG. 2b illustrates the vertical drive pulses 201. The
`vertical drive pulses are applied to the clock (CL) input
`terminal of D_?ip-flop (FF) 60 to set or latch a HIGH (a
`low) at the Q output terminal. The output of vertical
`saw generator 58 is illustrated by the ramp of FIG. 2c.
`This output from vertical saw generator 58 is applied to
`the reset input of flip flop 60. When the vertical saw
`output reaches a particular value, FF60 resets and the 6
`output which was set low changes states to a high level
`which is delivered to the clock input of astable ?ip flop
`62. The Q output of flip ?op 62 is a pulse, the duration
`of which is controlled by an R-C timing network,
`which is delivered to inverter 64. The output of inverter
`64 is a reference pulse, very similar in shape to the pulse
`delivered from pulse shaper 403 of FIG. 4, which is
`delivered via terminal “A” and switch S2 to the phase/
`frequency detector 405 of servo control loop 70 for use
`in controlling the speed and phase of shutter 44. The
`details of the servo control loop for controlling shutter
`44 will not be explained since it has already been ex
`plained with reference to the servo control loop of
`shutter 42.
`In operation, servo loop 70 controls the reference
`position of rotating shutter 44 so that the reference
`position occurs at the time of the phase-shifted pulse
`203. Thus, by changing the position of pulses 203 rela
`tive to pulses 201, the relative position of the shutter
`may be varied. Thus, one shutter, i.e. 42, has its speed
`and phase controlled by the vertical blanking pulse of a
`television signal while the other shutter, i.e., 44, is con
`trolled based on light in the scene. In another arrange
`ment switch S1 of FIG. 2a may be switched to the
`manual position wherein the phasing of shutter 44 is
`controlled manually so that in this arrangement, for
`example, the iris servo control can be used for the expo
`sure control while the shutter servo is maintained in a
`?xed position. As suggested above there are several
`different arrangement for this time exposure control. In
`one arrangement the shutters could be manually posi
`tioned to just permit a slit of light to pass through thus
`effecting a true stop action output from the camera. In
`the other arrangements “aperture preferred” or “expo
`sure preferred” systems may be provided.
`Four possible modes of operation will be described.
`In one operating mode the iris of the lens may be set to
`a ?xed “f” number and the shutter control may be man
`ually controlled to preserve signal constancy. In an
`other operating mode the shutter timing is set to a ?xed
`value and the iris is manually controlled to preserve
`signal constancy. In a third arrangement the iris of the
`lens may be set to a ?xed “f’ number and the shutter
`timing servo may be set to an automatic position to
`preserve signal constancy. In a fourth arrangement the
`shutter timing is set to a ?xed value and the iris servo is
`operated in the automatic position to preserve signal
`constancy. Such an arrangement provides a great deal
`of latitude in providing special effects and creating
`special artistic effects.
`
`

`
`20
`
`4,532,550
`8
`7
`While the principles of the present invention have
`9. The camera according to claim 8 wherein said
`charge-coupled device is a frame transfer imager.
`been demonstrated with particular regard to the illus
`trated structures of the Figures, it will be realized that
`10. A camera, comprising:
`image transducing means including a photosensitive
`various departures from such illustrated structures may
`be undertaken in practice of the invention. The widths
`surface for generating signal in response to re
`of the blades of the two shutters may be made unequal,
`ceived radiant energy from a scene;
`if desired. While especially advantageous for solid-state
`a ?rst shutter for blocking radiant energy from said
`imagers, the described arrangements may be applicable
`scene from reaching said photosensitive surface
`to camera tubes. The embodiments described use rotat
`during a portion of a television ?eld;
`ing shutters, but linear or other types of shutters could
`?rst motor means, coupled to said ?rst shutter, for
`be used.
`driving said ?rst shutter;
`What is claimed is:
`?rst servo control means, coupled to said ?rst motor
`1. A television camera, comprising:
`means, for maintaining a predetermined speed and
`solid-state image transducing means including a pho
`phase of said ?rst shutter;
`tosensitive surface for generating signal in response
`a second shutter coaxially arranged with said ?rst
`to received radiant energy from a scene during an
`shutter for varying the portion of a television ?eld
`integration interval; and
`during which radiant energy is blocked;
`optical shutter means arranged to block radiant en
`second motor means, coupled to said second shutter,
`ergy from said scene from reaching said photosen
`for driving said second shutter; and
`sitive surface during all of a television ?eld except
`second servo control means, coupled to said second
`during a portion of said integration interval, said
`motor means, for maintaining the speed of said
`optical shutter means being automatically control
`second shutter and for controlling the phase of said
`lable in response to the level of said received radi
`second shutter with respect to said ?rst shutter to
`ant energy for varying that portion of said integra
`vary that portion of a television ?eld during which
`tion interval during which radiant energy is
`radiant energy is blocked.
`blocked.
`11. The camera according to claim 10 wherein said
`2. The camera according to claim 1 wherein said
`image transducing means is a charge-coupled device.
`solid-state image transducing means is a charge-coupled
`12. The camera according to claim 11 wherein said
`device.
`charge-coupled device is a frame transfer imager.
`3. The camera according to claim 2 wherein said
`13. The camera according to claim 12 wherein at least
`charge-coupled device is a frame transfer imager.
`a part of said portion of a television ?eld is the transfer
`4. A television camera, comprising:
`interval when signal is transfered from an imaging area
`solid-state image transducing means including a pho
`of said device to a storage area of said device.
`tosensitive surface for generating signal in response
`14. A television camera, comprising:
`to received radiant energy from a scene during an
`image transducing means including a photosensitive
`integration interval; and
`surface for generating signal in response to re
`?rst and second shutters arranged to block radiant
`ceived radiant energy from a scene;
`energy from said scene from reaching said photo
`?rst light control means for controlling the relative
`sensitive surface during all of a television ?eld
`amount of radiant energy from said scene that im
`except during a portion of said integration interval,
`pinges on said photosensitive surface;
`the relative positions of said ?rst and second shut
`?rst feedback means for automatically controlling
`ters being automatically adjustable in response to
`said ?rst light control means to compensate for the
`the level of said received radiant energy to vary
`brightness of said scene, said ?rst feedback means
`that portion of said integration interval during
`being switchable into a manual operating mode
`which radiant energy is blocked.
`whereby the relative amount of radiant energy is
`5. The camera according to claim 4 wherein said
`?xed;
`solid-state image transducing means is a charge-coupled
`second light control means for controlling the rela
`device.
`tive time that radiant energy from said scene im
`6. The camera according to claim 5 wherein said
`pinges on said photosensitive surface; and
`charge-coupled device is a frame transfer imager.
`second feedback means for automatically controlling
`7. A television camera, comprising:
`said second light control means to compensate for
`solid-state image transducing means including a pho
`the brightness of said scene, said second feedback
`tosensitive surface for generating signal in response
`means being switchable into a manual operating
`to received radiant energy from a scene during an
`mode whereby said relative time is ?xed.
`integration interval;
`15. The television camera according to claim 14
`a ?rst shutter having a first blade for blocking radiant
`wherein said ?rst light control means is an iris control
`energy from said scene from reaching said photo
`and said second light control means is a variable aper
`sensitive surface during recurrent ?xed duration
`ture shutter.
`portions of a television ?eld which do not include
`16. The television camera according to claim 15
`said integration interval; and
`wherein said image transducing means is a charge-cou
`a second shutter having a second blade cooperatively
`pled device.
`arranged with said ?rst shutter and automatically
`17. The camera according to claim 16 wherein said
`controlled such that radiant energy is blocked dur
`charge-coupled device is a frame transfer imager.
`ing recurrent variable duration portions of a televi
`sion ?eld which include said integration interval.
`18. The camera according to claim 17 wherein at least
`a part of said portion of a television ?eld is the transfer
`8. The camera according to claim 7 wherein said
`solid-state image transducing means is a charge-coupled
`interval when signal is transfered from an imaging area
`device.
`of said device to a storage area of said device.
`
`55
`
`65
`
`25
`
`35
`
`40
`
`45
`
`

`
`4,532,550
`9
`19. The camera according to claim 4 wherein said
`?rst and second shutters comprise rotating blade shut
`ters.
`20. The camera according to claim 9 wherein said
`?rst and second shutters comprise rotating blade shut
`ters.
`21. The camera according to claim 14 wherein
`
`5
`
`10
`changes in the amount of light impinging upon said
`photosensitive surface in response to manual operation
`of one of said ?rst and second feedback means, is com
`pensated for by automatic operation of the other of said
`?rst and second feedback means.
`* * *
`*
`
`*
`
`15
`
`20
`
`25
`
`35
`
`45
`
`50
`
`55
`
`65