CA1304494C - Three-dimensional imaging apparatus - Google Patents
Three-dimensional imaging apparatusInfo
- Publication number
- CA1304494C CA1304494C CA000596352A CA596352A CA1304494C CA 1304494 C CA1304494 C CA 1304494C CA 000596352 A CA000596352 A CA 000596352A CA 596352 A CA596352 A CA 596352A CA 1304494 C CA1304494 C CA 1304494C
- Authority
- CA
- Canada
- Prior art keywords
- signal charges
- photoelectric converting
- field
- converting elements
- vertical transfer
- Prior art date
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Abstract
ABSTRACT OF THE DISCLOSURE
A three-dimensional imaging apparatus comprises a TV camera, a plurality of light path systems including a plurality of mirrors and shutters for interrupting the light. Images of an object of the light path systems are selected alternately in synchronism with the field scan of the TV camera to allow in a single TV camera, thus producing a three-dimensional image. The TV camera includes an image pick-up device having photo-electric transducer elements arranged two-dimensionally and corresponding vertical transfer means, and the signal charges stored in the photo-electric transducer elements arranged two-dimensionally are transferred to the vertical transfer means at the same time. The images of an object entering the TV camera are switched substantially at the same timing as the signal charges are transferred from the photo-electric transducer elements to the vertical transfer means.
A three-dimensional imaging apparatus comprises a TV camera, a plurality of light path systems including a plurality of mirrors and shutters for interrupting the light. Images of an object of the light path systems are selected alternately in synchronism with the field scan of the TV camera to allow in a single TV camera, thus producing a three-dimensional image. The TV camera includes an image pick-up device having photo-electric transducer elements arranged two-dimensionally and corresponding vertical transfer means, and the signal charges stored in the photo-electric transducer elements arranged two-dimensionally are transferred to the vertical transfer means at the same time. The images of an object entering the TV camera are switched substantially at the same timing as the signal charges are transferred from the photo-electric transducer elements to the vertical transfer means.
Description
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The present invention relates to a three-dimensional imaging apparatus for picking up an image of an object stereoscopically.
Fig. 1 is a block diagram showing a schematic configuration of a three-dimensional imaging apparatus according to an embodiment of the present invention.
Fig. 2(a) is a diagram schematically showing a configuration of an image pick-up device using a three-dimensional imaging apparatus.
Figs. 2(b) is a timing chart for operation and switching liquid crystal shutters.
Figs. 3(a) and 3(b) are timing charts for the operation of an image pick-up device and switching of liquid crystal shutters.
Figs. 4(a) and 4(b) are timing charts for the operation using an image pick-up tube as a three-dimensional imaging apparatus.
Fig. 5 is a block diagram of a conventional three-dimensional imaging apparatus.
Fig. 6 is a block diagram showing optical shutters.
In a basic method conventionally known for imaging an object three-dimensionally, an image of an object is picked up by use of two television cameras held at a predetermined angle to each other and GUtpUt signals of these two ~; 25 television cameras are switched alternately for each field.
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A configuration of such a three-dimensional imaging apparatus is schematically illustrated in Fig. 5. In Fig. 5, the side A delineated ~y one-dot chain shows a three-dimeneional imaging apparatus and he side B a three-dimensional display unit. In this drawing, reference numeral 1 designates an object to be imaged, numeral 2 a television camera A, and numeral 3 a television camera B. The television cameras A
and B have the lenses thereof arranged on the front of the imaging surface thereof. Numeral 4 designates a sync signal generator, numeral 5 a switch, and numeral 6 an adder, which make up a three dimensional imaging apparatus. Numeral 7 designates a sync separator, numeral 8 a monitor television, and numeral 9 a pair of spsctacles, which make up a three-dimensional display unit.
The three-dimensional imaging apparatus and the three-dimensional display unit configured as described above are well known and there~ore will be explained hereinafter only briefly. First, reference is had to the three-dimensional imaging apparatus. The teleYision cameras 2 and 3 are arranged at a given angle e to the ` ~ - 2 -`' ' ,- .
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l same object l~ Also, the scanning timings of the tele-vision cameras 2 and 3 are held in synchronous relation-ship with each other. As a result, the television cameras 2 and 3 are supplied with a pulse-like signal at the same time as required for driving the television cameras from the sync signal generator 4. (The TV cameras
The present invention relates to a three-dimensional imaging apparatus for picking up an image of an object stereoscopically.
Fig. 1 is a block diagram showing a schematic configuration of a three-dimensional imaging apparatus according to an embodiment of the present invention.
Fig. 2(a) is a diagram schematically showing a configuration of an image pick-up device using a three-dimensional imaging apparatus.
Figs. 2(b) is a timing chart for operation and switching liquid crystal shutters.
Figs. 3(a) and 3(b) are timing charts for the operation of an image pick-up device and switching of liquid crystal shutters.
Figs. 4(a) and 4(b) are timing charts for the operation using an image pick-up tube as a three-dimensional imaging apparatus.
Fig. 5 is a block diagram of a conventional three-dimensional imaging apparatus.
Fig. 6 is a block diagram showing optical shutters.
In a basic method conventionally known for imaging an object three-dimensionally, an image of an object is picked up by use of two television cameras held at a predetermined angle to each other and GUtpUt signals of these two ~; 25 television cameras are switched alternately for each field.
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A configuration of such a three-dimensional imaging apparatus is schematically illustrated in Fig. 5. In Fig. 5, the side A delineated ~y one-dot chain shows a three-dimeneional imaging apparatus and he side B a three-dimensional display unit. In this drawing, reference numeral 1 designates an object to be imaged, numeral 2 a television camera A, and numeral 3 a television camera B. The television cameras A
and B have the lenses thereof arranged on the front of the imaging surface thereof. Numeral 4 designates a sync signal generator, numeral 5 a switch, and numeral 6 an adder, which make up a three dimensional imaging apparatus. Numeral 7 designates a sync separator, numeral 8 a monitor television, and numeral 9 a pair of spsctacles, which make up a three-dimensional display unit.
The three-dimensional imaging apparatus and the three-dimensional display unit configured as described above are well known and there~ore will be explained hereinafter only briefly. First, reference is had to the three-dimensional imaging apparatus. The teleYision cameras 2 and 3 are arranged at a given angle e to the ` ~ - 2 -`' ' ,- .
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l same object l~ Also, the scanning timings of the tele-vision cameras 2 and 3 are held in synchronous relation-ship with each other. As a result, the television cameras 2 and 3 are supplied with a pulse-like signal at the same time as required for driving the television cameras from the sync signal generator 4. (The TV cameras
2 and 3 correspond to the right and left eyes respectively of the human being.) A video output signal of each of the TV cameras 2 and 3 is connected to the terminals A
and B of the switch 5 respectively. The switch 5 is controlled by a field pulse supplied from the sync signal generator 4. At the terminal C of the s~7itch 5, there are produced a video signal from the TV camera l in the first field and a video signal from the TV camera 2 in the second field as alternate output signals. A video signal thus produced by being switched and a sync signal from the sync signal generator 4 are applied to the adder 6 thereby to produce a three-dimensional video signal.
A drive pulse for the television cameras, a field ~` 20 pulse and a sync signal produced from the sync signal generator 4 are of course in synchronism with each other.
Now, the three-dimensional display unit will be explained. A thrae-dimensional video signal produced from the above-mentioned three-dimensional imaging apparatus is transmitted to a three-dimensional display unit by predetermined means. The three-dimensional video signal thus transmitted is supplied to and displayed on the monitor television 8. The three-dimensional video ~3~ 3~
1 signal displayed on the monitor TV 8 is obtained from the video output signals of the TV cameras 2 and 3 alternated with each other, and therefore is not felt as a three-dimensional ima~e in its direct form but as an unnatural double image.
If the image displayed on the monitor TV 8 is to be watched as a three-dimensional image, the image picked up by the TV camera 2 is observed only with the right eye, and the image taken by the TV camera 3 with the left eye of the viewer. Specifically, the images displayed on the monitor T~ 8 are selected in such a manner that the image in the first field enters the right eye and the image in the second field enters the left eye.
As a means for accomplishing this purpose, the spectacles 9 having an optical shutter function are used to select optical signals from the monitor TV 8 in such a way that the image of the first field is observed by the right eye, and the image of the second field by the left eye. The sync separator 7 produces a field pulse synchronous with the sync signal. The field pulse output signal from the sync separator 7 is assumed to be at high level in the first field and low level at the second field. The field pulse is applied to the spectacles 9, so that the optical shutters built in the spectacles 9 are turned on and off alternately thereby to select the optical signal from the monitor TV 8 for the right and left eyes. Specifically, the optical shutter for the right eye of the spectacles 9 passes the light in the first field, while the light is . ~
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1 masked by the optical shutter for the left eye. In reverse, the optical shutter for the left eye of the spectacles 9 passes the light in the second field, while the light is mas~ed by the optical shutter for the right eye. In this manner, the optical signal from the monitor TV 8 is selected to observe a three-dimensional image.
Now, the optical shutters will be briefly explained. Each optical shutter, which may be of mechanical type, is used in the form of liquid crystal shutter in the present embodiment. In the li~uid crystal shutter, inter-ruptions of light is capable of being controlled by a voltage, and the response speed is sufficiently high as compared with the field scanning frequency of the TV
camera. It is also long in service life as compared with the mechanical shutter and easier to handle.
A liquid crystal shutter will be briefly described below with reference to Fig. 6 schematically showing an image of an object. Numerals 10, 11 designate deflection plates, numeral 12 a liquid crystal, numerals 13, 14 transparent electrodes, numeral 15 a rectangular wave generator, numerals 16, 17 AND gates, numerals 20, 21 capacitors, numeral 18 an inverter, and numeral 19 a field pulse input terminal. In a basic configuration of an optical shutter, -two types of deflection plates 10, 11 have a liquid crystal (twist nematic type) 12 arranged therebetween and the liquid crystal is impressed with an electric field. In this way, an optical shutter is -~ configured for interrupting light. The twist nematic ;~ - 5 -~3C?~L9~
1 crystal is well known and will not be described any further.
The optical section of the optical shutters 100, 200 is made up of deflection plates, a liquid crystal and a transparent electrode. The deflection plate 10 passes only the horizontal polarized wave and the deflection plate 11 only the vertical polarized wave of the light from the object. The transparent electrode 14 is grounded. The transparent electrode 13 is used for applying an electric field to the liquid crystal 12. In this configuration, if no voltage is applied to the transparent electrode 13, the horizontal polarized wave that has passed through the deflection plate 10 also passes through the liquid crystal layer 12 thereby to be phase-shifted into a vertical polarized wave, and the vertical polarized wave that has passed through the liquid crystal layer 12 is transmitted through the deflection plate 11. Specifically, the liquid crystal shutter is thus transmittable, so that the light from the monitor is capable of reaching the eyes of the human being. If a voltage is applied ~o the transparent electrode 13, on the other hand, the horizontal polarized wave that has passed through the deflection plate 10 is passed also through the liquid~crystal layer 12 but not phase-shifted and maintains the horizontal polarized state thereof. As a result, the horizontal polarized wave that has passed through the liquid crystal layer 12 is unable to pass through the deflection plate 11.
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1 Specifically, the liqujd crystal shutter is masked, and therefore the light from the monitor is unable to reach the eyes of the human being. As described above, the transparent electrode 14 is grounded, and the transparent electrode 13 is supplied with a drive signal through capacitors 20, 21. The drive voltage applied to the transparent electrode 13 is about 10 V with a drive frequency of about 200 Hæ. This drive signal is produced by the rectangular wave generator 15, the AND circuits 16, 17, the inverter 18 and the field pulse input terminal 19. Specifically, the rectangular wave generator 15 generates a rectangular wave of about 200 Hz, and this output signal is applied to the AND circuits 16 and 17 at the same time. The AND circuit 16 is supplied from the field pulse input terminal 19 with a field pulse high in level for the first field and low in level for the second field. As a result, the output signal of the AND
circuit 16 provides a drive signal for the liquid crystal ; layer only for the first field. The AND circuit 17, on the other hand~ is supplied from the field pulse input terminal 19 with a field pulse inverted by the inverter 18, and therefore the output signal of the A~D circuit 17 makes up a drive voltage of the liquid crystal layer only for the second field. A liquid crystal shutter is thus constructed. Specifically, the shutter 100 on the right side of the spectacles 9 passes the light for the first field, and the shutter 200 on the left side of the spectacles 9 allows to pass the light for the second field.
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The three~dimensional imaging apparatus having the configuration described above, however, requires two TV
cameras and high in cost. It is also necessary to adjust precisely the image angle, focal point and angle of an obj~ct to the two TV cameras in picking up an image by the two different TV cameras~ As a result, a long time is consumed as compared with the actual time of imaging. Further, the problem has been posed by the lack of mobility.
The present invention provides a three-dimensional imaging apparatus having a low-cost configuration which is easy to adjust. According to the present invention, there is provided a three-dimensional imaye pickup apparatus having a television camera provided with an imaging device which comprises at least photoelectric converting elements and vertical transfer stages corresponding to said photoelectric converting elements, said imaging device reading out signal charges stored in said photoelectric converting elements one or more times in one field by transferring the signal charges simultaneously to said vertical transfer stages, wherein object images transmitted through two optical paths are alternately selected for every field to be picked up, substantially synchronous with the transfer timing of transferring the signal charges from said photoelectric converting elements to said vertical transfer stages~
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1 In this confi,guration, object images from two light path systems are selected alternately in synchronism with the field scan of the imaging device thereby to pick up a three-dimensional image with a single TV camera.
In the process, an image pick-up device used for the TV
camera includes at least a photo-electric transducer and a vertical transfer means. In the case where the photo-electxic transducer doubles as a vertical transfer means, however, a signal charge storage section is provided along the extension of transfer by the vertical transfer means, so that signal charyes stored in each photo-electric transducer element are transferred to corresponding vertical transfer means substantially at the same time thereby to pick up an image for a screen. For this purpose, an image pick-up device capable of plane scan is used. The storage time of signal charges at each photo-electric transducer element of the image pick--up device is not more than the scanning time of a field. The object images from two light path systems entering the image pick-up device are alternately switched for each field by use of optical shutters at substantially the same timing as signals charges are transferred from the photo-electric transducer of the image pick-up device to the vertical transfer means. By using this image pick-up device, keeping the storage time of signal charges at each photo-electric transducer element of the image pick-up device at not more than the scanning period for a field, and switching the optical path systems at substantially g .
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the same timing as the signal charges are trallsferred from the photo-electric transducer of the image pick-up device to the vertical transfer means this way, it is possible to pick up a three-dimensional image of high image quality with a single TV camera.
A three-dimensional imaging apparatus according to an embodiment of the present invention will be explained below with reference to the accompanying drawings.
In Fig. 1, the side A designated by one-dot chain is a three-dimensional imaging apparatus and the side B a three-dimensional display unit. Reference numeral 40 designates a TV camera, numeral 4 a sync signal generator, numeral 6 an adder, numerals 22, 23, 26 mirrors, numerals 24, 27 liquid crystal shutters, numeral 25 a half mirror, numeral 28 an inverter, numerals 16, 17 AND circuits, numeral 15 a rectangular wave generator~ numerals 20, 21 capacitors, and numeral 100 a liquid crystal drive circuit. The mirrors 22, 23, the liquid crystal shutter 24 and the half mirror 25 make up a first light path system, and the mirror 26, the liquid ~ 20 crystal shutter 27 and the half mirror 25 a second light path :~ system. ~he sync signal generator 4, the adder 6, mirrors 22, 23, 26, the liquid crystal shutters 24, 27, hal~ mirror 25 and the TV camera 40 provide a three-dimensional imaging apparatus.
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1 Now, the operation of this configuration will be explained. The TV camera 40 is supplied with a pulse-like signal required for driving the TV camera from the sync signal generator 4. ~lso, the drive pulse, the field pulse and the sync signal for the TV camera produced from the sync signal generator 4 are all in synchronism with each other. The light entering from an ohject through the mirrors 22, 23, and liquid crystal shutter 24 passes through the half mirror 25 and forms an image at the photo-electric transducer section o~ the image pick-up device of the TV camera 40. The light entering from the object through the mirror 26 and the liquid crystal shutter 27, on the other hand, is bent by 90 degree through the half mirror 25 and forms an image at the photo-electric conversion section of the image pick-up device of the TV camera 40. The optical axes of the light path systems 1 and 2 are arranged at a given angle ~ (not shown) against the same object. (The light path systems 1 and 2 correspond to the right and left eyes respectively of the man).
The optical shutter used for the present invention is a liquid crystal shutter long in service life, in which the light interruptions can be controlled by a voltage and the response speed is sufficiently hi~h as compared with the field scanning frequency of the TV camera.
This optical shutter using liquid crystal is substantially of the same construction as the one described with reference to Fig. ~. Since they are also the sa~.e in .
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1 operation and will be described only briefly.
The li~uid crystal shutters 24, 27 are comprised of deflection plates 10, 11, liquid crystal 12 and transparent electrodes 13, 14 shown in Fig. 6. The liquid crystal shutters 24, 27 are controlled by the drive pulse supplied from the liquid crystal shutter drive circuit. As already explained with reference to Figs. 4 and 6, the liquid crystal shutters pass the light when the field pulse supplied to the AND circuits 1~, 17 making up the liquid crystal shutter drive circuit is at low level. The field pulse is high in level for the first field, and low in level for the second field. As a result, the liquid crystal shutter 27 shown in Fig. 1 passes the light for the first field, and the liquid crystal shutter 24 allows the light to pass for the second field. The light signal representing an object image that has passed the second light path system enters the image pick-up device for the first field, and the light signal carrying an object image that has passed the first light path system enters the image pick-up device for the second field.
The image pick-up device is basically adapted to receive a light signal at the photo-electric transducer section from an object image over the period of one field or one frame, and after accumulating (storing~ ~he signal charges over a period of one field or one frame upon photo-electric conversion, reads out the signal charges thus stored. Thereforel an output signal is delayed by l one field behind the light signal entering the image pick-up surface.
If an image pick-up device or image pick-up tube of linear sequential scan type or an X-Y matrix image pick-up device (MOS image pick-up device) is used for the TV camera 40, it is impossible to obtain a three-dimensional imaging signal for the reason explained below with reference to Fig~ 4. Fig. 4(a) is a diagram illustratively showing the scanning field of the TV camera and the liquid crystal shutter conditions and the potential at point A of the image pick-up surface (photo-electric transducer section) of the image pick-up device of linear se~uential scan type, and Fig. 4(b) a diagram showing the image pick-up surface of an image pick-up device of linear sequential scan type. A light signal enters an image pick-up device after passing through a second light path system (liquid crystal shutter 27) from an object image in the first field, and after passing through a first light path system (liquid crystal shutter 24) in the second field. By way of explanation, the light signal that has passed the first light path system is called the light R, and the one that has passed the second light path system the light L. Explanation will also be made of a case in which an image pick-up device of linear sequential scan type, that is, an image pick-up tube, is used. The potential at point A of the image pick-up surface of the image pick-up tube undergoes a gradual change with time as shown in Fig. 4(a) by storage ~-3~
1 of signal charges, and at a predetermined timing, the signal charges at point A are read out. The signal charges generated at point A, however, are a mixture of a component SR of the signal charges generated by the light passing through the first light path system and the signal charges SL generated by the light passing through the second light path system as obvious from Fig. 4(a). In other words, light from two light path systems are mixed and enter the image pick-up device, and therefore a video signal obtained from the TV camera 40 is blurred, thereby making it impossible to produce a three-dimensional imaging signal. For this reason, the present embodiment uses an image pick-up device for the TV camera 40, which comprises at least a photo-electric transducer and a vertical transfer means or a photo-electric transducer doubling as a vertical transfer ~eans with a signal charge storage section along the extension of transfer by the vertical transfer means. The time of signal charge storage at each photo-electric transducer element of the image pick-up device is kept less than one field of scan period, and images o~ an object from two light path systems entering the image pick-up device are alternately switched for each field by an optical shutter at substantiall~ the same timing as the transfer of signal charges from the photo-electric transducer of the image pick-up device configured as above to the ~ vertical trans~er means.
-; A specific example of an image pick-up device : ,:
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1 usable according to the present invention is an inter-line transfer charge-coupled device (hereinafter abbre-viated as IL-CCD), frame transfer charge-coupled device (hereinafter abbreviated as FT-CCD) or frame inter-line transfer charge-coupled device (hereinafter abbreviated as FIT-CCD). Explanation below will be made about a case using IL-CCD as an image pick-up device. Fig. 2(a) is a diagram showing a schematic configuration of an inter-line transfer charge coupled device (IL-CCD) used with a three-dimensional imaging apparatus according to an embodiment of the present invention. The configuration and operation of the IL-CCD, which is well known, will be briefly described. The IL-CCD, as shown in Fig. 2(a), comprises a light-receiving section A and a horizontal transfer section R. Numeral 41 designates a semiconductor substrate, and the light-receiving section A includes a photo-electric transducer (photo-diode) 42 aligned two-dimensionally, a gate 44 for reading the signal charges stored in the photo-electric converter, and vertical transfer means 43 having a CCD for vertical transfer of signal charges thus read out by the gate. The parts other than the photo-electric converter 42 are optically masked by an aluminum mask (not shown). The photo-electric transducer is separated by a channel stopper 45 in both horizontal and vertical directions. An over-;~ flow drain (not shown~ and an overflow control gate (not shown) are arranged in the vlcinity of the photo-electric transducer. The vertical transfer means 43 is ' .
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1 comprised of a plurality of horizontally-connected polysilicon electrodes ~Vl, ~V2, ~V3 and ~V4 which are connected vertically for each four horizontal lines.
The horizontal transfer section B includes a horizontal transfer means 46 of CCD and a signal charge detector 47. The horizontal transfer means 46 includes transfer electrodes ~Hl, ~H2 and ~H3 connected at intervals of three electrodes in horizontal direction. The horizontal transfer means 46 transfers signal charges transferred thereto from the vertical transfer means toward the charge detector 47. The charge detector 47 includes a well-known floating diffusion amplifier for converting the signal charges into a signal voltage.
Now, the operation will be briefly explained.
The signal charges stored by photo-electric conversion at the photo-electric transducers 42, 42' are trans-ferred to the vertical transfer means 43 from the photo-electric transducers 42, 42' by a signal read pulse ~CH
superimposed on ~Vl and ~V3 of the vertical transfer pulses ~Vl to ~V4 applied to the vertical transfer gate during the vertical flyback period. In the process, if the signal read pulse ~CH is applied to ~Vl, only the signal charges stored in the photo-electric transducer ;~ 42 are transferred to the potential well under the ~V1 electrode, whlle if the signal read pulse ~CH is applied to ~V3, only the signal charges stored in the photo-; electric transducer section 42' are transferred to the potential well under the ~3 electrode.
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1 In this way, a signal charges stored in the photo-electric transducer sections 42, 42' arranged two-dimensionally are transferred to the vertical transfer means 43 upon application of the signal read pulse ~CH.
As a result, if the signal read pulse ~CH is superimposed on ~V1 and ~V3 alternately for every other field, the signal is read out of each photo-electric transducer section for each frame, and therefore the frame storage operation is performed by IL-CCD.
The signal charges transferred from the photo-electric transducer 42 to the potential well under the electrode of ~Vl or ~V3 of the vertical transfer means 43 are transferred to the potential well under the corre-sponding horizontal tansfer electrode of the horizontal transfer means 46 one horizontal line at a time for each horizontal scan period by the vertical transfer pulses ~Vl, ~V2, ~V3 and ~V4. Also, if the signal read pulse ~CH is applied to both ~Vl and ~V3 at substantially the same time during one field period, on the other hand, the signal charges stored in the photo-electric transducer 42 are transferred to the potential well under the ~V1 elec-trode, and the signal charges stored in the photo-electric transducer 42' to the potential well under the ~V3 electrode respectively, so that each photo-electric transducer reads a signal for each field, and thus the IL-CCD performs the field storage operation. In the process, the signal ~ charges transferred to the potential well under the ~Vl :~ and ~V3 electrodes of the vertical transfer means 43 from ::
1 the photo-electric transducer 42 are mixed with siynal charges L for the first ~ield and M for the second field from the photo-electric transducer vertically adjacent thereto in the vertical transfer means, and then trans-ferred one horizontal line at a time for each horizontalscan to the potential well under a corresponding horizontal transfer electrode of the horizontal transfer means 46 by the vertical transfer pulses ~Vl, ~V2, ~V3 and ~V4. The signal charges thus transferred to the potential well under the horizontal transfer electrode are further transferred to the signal charge detection section 47 arranged in horizontal direction by the high-speed horizontal transfer pulses ~Hl, ~H2 and ~H3, and after being converted into a voltage signal, are produced from the image pick-up device as a video signal.
The timing of reading the IL-CCD signal and the timing of driving the liquid crystal shutters in the three-dimensional imaging apparatus according to the present invention, together with the potential change at point Z of the photo-electric transducer in Fi~. 2(a) are shown in Fig. 2~b). Fig. 2~b~ also shows a pule (VBLK) representing the vertical flyback period, a field pulse produced from the sync signal generator 4 of Fig. 1, the signal read timing of IL-CCD, the timing of driving the ~5 liquid crystal shutters, the potential change at point Z
of the photo-electric transducer and the output signal of : the image pick-up device. Signals are read out of the photo-electric transducer to the vertical transfer means ~3(~9~
1 (transfer of signal charges) during the vertical flyback period, and the switching of the liquid crystal shutters substantially coincides with the read timing of the signal from the photo-electric transducer to the vertical transfer means. The timing at which the field pulses are switched also substantially coincides with the timing at which the signal is read from the photo-electric transducer to the vertical transfer means. If the image pick-up device and the liquid crystal shutters are driven at these timings, tlle light signal carrying an object image enters the image pick-up device after passing through the second light path for the first field and after passing through the first light path for the second field respectively.
In the process, the potential at point Z of the~ image pick-up surface of the image pick-up device changes with time slowly as shown in Fig. 2(b), and at a predetermined timing (with a signal read pulse applied to the vertical transfer means from the photo-electric transducer), the signal charges at point Z are transferred to the vertical transfer means. At the same time, the signal charges from the point Z, as obvious from Fig. 2(bj, make up only those produced by the light passed through the first light path or those generated by the light passing through the seo~d light path. Specifically, each pixel of the photo-electric transducer is not entered by light mixture from two light paths. By picking up an image of an ohject maintain-ing ~he drive timings and configuration mentioned above, a video signal due to an object image transmitted through ::
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l the light path system l i9 produced for the first field alterntely with a video signal due to an object image transmitted through the light path system 2 for the second field, thus producing a three-dimensional video signal.
According to the present embodiment, after signal charges of the photo-electric transducer are all transferred (read) to the vertical transfer means, these signal charges are mixed with those an adjacent photo-electric transducer in the vertical transfer means thereby to produce a video signal of field storage from the image pick-up device.
A second embodiment of the present invention will be explained with reference to Fig. 3. The IL-CCD
produces a video signal of field storage without mixing the signal charges of two adjacent photo-electric transducers as explained above. The principle of this operation will be explained with reference to Figs. 2(a~ and 3(b). Fig.
and B of the switch 5 respectively. The switch 5 is controlled by a field pulse supplied from the sync signal generator 4. At the terminal C of the s~7itch 5, there are produced a video signal from the TV camera l in the first field and a video signal from the TV camera 2 in the second field as alternate output signals. A video signal thus produced by being switched and a sync signal from the sync signal generator 4 are applied to the adder 6 thereby to produce a three-dimensional video signal.
A drive pulse for the television cameras, a field ~` 20 pulse and a sync signal produced from the sync signal generator 4 are of course in synchronism with each other.
Now, the three-dimensional display unit will be explained. A thrae-dimensional video signal produced from the above-mentioned three-dimensional imaging apparatus is transmitted to a three-dimensional display unit by predetermined means. The three-dimensional video signal thus transmitted is supplied to and displayed on the monitor television 8. The three-dimensional video ~3~ 3~
1 signal displayed on the monitor TV 8 is obtained from the video output signals of the TV cameras 2 and 3 alternated with each other, and therefore is not felt as a three-dimensional ima~e in its direct form but as an unnatural double image.
If the image displayed on the monitor TV 8 is to be watched as a three-dimensional image, the image picked up by the TV camera 2 is observed only with the right eye, and the image taken by the TV camera 3 with the left eye of the viewer. Specifically, the images displayed on the monitor T~ 8 are selected in such a manner that the image in the first field enters the right eye and the image in the second field enters the left eye.
As a means for accomplishing this purpose, the spectacles 9 having an optical shutter function are used to select optical signals from the monitor TV 8 in such a way that the image of the first field is observed by the right eye, and the image of the second field by the left eye. The sync separator 7 produces a field pulse synchronous with the sync signal. The field pulse output signal from the sync separator 7 is assumed to be at high level in the first field and low level at the second field. The field pulse is applied to the spectacles 9, so that the optical shutters built in the spectacles 9 are turned on and off alternately thereby to select the optical signal from the monitor TV 8 for the right and left eyes. Specifically, the optical shutter for the right eye of the spectacles 9 passes the light in the first field, while the light is . ~
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1 masked by the optical shutter for the left eye. In reverse, the optical shutter for the left eye of the spectacles 9 passes the light in the second field, while the light is mas~ed by the optical shutter for the right eye. In this manner, the optical signal from the monitor TV 8 is selected to observe a three-dimensional image.
Now, the optical shutters will be briefly explained. Each optical shutter, which may be of mechanical type, is used in the form of liquid crystal shutter in the present embodiment. In the li~uid crystal shutter, inter-ruptions of light is capable of being controlled by a voltage, and the response speed is sufficiently high as compared with the field scanning frequency of the TV
camera. It is also long in service life as compared with the mechanical shutter and easier to handle.
A liquid crystal shutter will be briefly described below with reference to Fig. 6 schematically showing an image of an object. Numerals 10, 11 designate deflection plates, numeral 12 a liquid crystal, numerals 13, 14 transparent electrodes, numeral 15 a rectangular wave generator, numerals 16, 17 AND gates, numerals 20, 21 capacitors, numeral 18 an inverter, and numeral 19 a field pulse input terminal. In a basic configuration of an optical shutter, -two types of deflection plates 10, 11 have a liquid crystal (twist nematic type) 12 arranged therebetween and the liquid crystal is impressed with an electric field. In this way, an optical shutter is -~ configured for interrupting light. The twist nematic ;~ - 5 -~3C?~L9~
1 crystal is well known and will not be described any further.
The optical section of the optical shutters 100, 200 is made up of deflection plates, a liquid crystal and a transparent electrode. The deflection plate 10 passes only the horizontal polarized wave and the deflection plate 11 only the vertical polarized wave of the light from the object. The transparent electrode 14 is grounded. The transparent electrode 13 is used for applying an electric field to the liquid crystal 12. In this configuration, if no voltage is applied to the transparent electrode 13, the horizontal polarized wave that has passed through the deflection plate 10 also passes through the liquid crystal layer 12 thereby to be phase-shifted into a vertical polarized wave, and the vertical polarized wave that has passed through the liquid crystal layer 12 is transmitted through the deflection plate 11. Specifically, the liquid crystal shutter is thus transmittable, so that the light from the monitor is capable of reaching the eyes of the human being. If a voltage is applied ~o the transparent electrode 13, on the other hand, the horizontal polarized wave that has passed through the deflection plate 10 is passed also through the liquid~crystal layer 12 but not phase-shifted and maintains the horizontal polarized state thereof. As a result, the horizontal polarized wave that has passed through the liquid crystal layer 12 is unable to pass through the deflection plate 11.
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1 Specifically, the liqujd crystal shutter is masked, and therefore the light from the monitor is unable to reach the eyes of the human being. As described above, the transparent electrode 14 is grounded, and the transparent electrode 13 is supplied with a drive signal through capacitors 20, 21. The drive voltage applied to the transparent electrode 13 is about 10 V with a drive frequency of about 200 Hæ. This drive signal is produced by the rectangular wave generator 15, the AND circuits 16, 17, the inverter 18 and the field pulse input terminal 19. Specifically, the rectangular wave generator 15 generates a rectangular wave of about 200 Hz, and this output signal is applied to the AND circuits 16 and 17 at the same time. The AND circuit 16 is supplied from the field pulse input terminal 19 with a field pulse high in level for the first field and low in level for the second field. As a result, the output signal of the AND
circuit 16 provides a drive signal for the liquid crystal ; layer only for the first field. The AND circuit 17, on the other hand~ is supplied from the field pulse input terminal 19 with a field pulse inverted by the inverter 18, and therefore the output signal of the A~D circuit 17 makes up a drive voltage of the liquid crystal layer only for the second field. A liquid crystal shutter is thus constructed. Specifically, the shutter 100 on the right side of the spectacles 9 passes the light for the first field, and the shutter 200 on the left side of the spectacles 9 allows to pass the light for the second field.
. . ~
The three~dimensional imaging apparatus having the configuration described above, however, requires two TV
cameras and high in cost. It is also necessary to adjust precisely the image angle, focal point and angle of an obj~ct to the two TV cameras in picking up an image by the two different TV cameras~ As a result, a long time is consumed as compared with the actual time of imaging. Further, the problem has been posed by the lack of mobility.
The present invention provides a three-dimensional imaging apparatus having a low-cost configuration which is easy to adjust. According to the present invention, there is provided a three-dimensional imaye pickup apparatus having a television camera provided with an imaging device which comprises at least photoelectric converting elements and vertical transfer stages corresponding to said photoelectric converting elements, said imaging device reading out signal charges stored in said photoelectric converting elements one or more times in one field by transferring the signal charges simultaneously to said vertical transfer stages, wherein object images transmitted through two optical paths are alternately selected for every field to be picked up, substantially synchronous with the transfer timing of transferring the signal charges from said photoelectric converting elements to said vertical transfer stages~
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1 In this confi,guration, object images from two light path systems are selected alternately in synchronism with the field scan of the imaging device thereby to pick up a three-dimensional image with a single TV camera.
In the process, an image pick-up device used for the TV
camera includes at least a photo-electric transducer and a vertical transfer means. In the case where the photo-electxic transducer doubles as a vertical transfer means, however, a signal charge storage section is provided along the extension of transfer by the vertical transfer means, so that signal charyes stored in each photo-electric transducer element are transferred to corresponding vertical transfer means substantially at the same time thereby to pick up an image for a screen. For this purpose, an image pick-up device capable of plane scan is used. The storage time of signal charges at each photo-electric transducer element of the image pick--up device is not more than the scanning time of a field. The object images from two light path systems entering the image pick-up device are alternately switched for each field by use of optical shutters at substantially the same timing as signals charges are transferred from the photo-electric transducer of the image pick-up device to the vertical transfer means. By using this image pick-up device, keeping the storage time of signal charges at each photo-electric transducer element of the image pick-up device at not more than the scanning period for a field, and switching the optical path systems at substantially g .
, ~3~
the same timing as the signal charges are trallsferred from the photo-electric transducer of the image pick-up device to the vertical transfer means this way, it is possible to pick up a three-dimensional image of high image quality with a single TV camera.
A three-dimensional imaging apparatus according to an embodiment of the present invention will be explained below with reference to the accompanying drawings.
In Fig. 1, the side A designated by one-dot chain is a three-dimensional imaging apparatus and the side B a three-dimensional display unit. Reference numeral 40 designates a TV camera, numeral 4 a sync signal generator, numeral 6 an adder, numerals 22, 23, 26 mirrors, numerals 24, 27 liquid crystal shutters, numeral 25 a half mirror, numeral 28 an inverter, numerals 16, 17 AND circuits, numeral 15 a rectangular wave generator~ numerals 20, 21 capacitors, and numeral 100 a liquid crystal drive circuit. The mirrors 22, 23, the liquid crystal shutter 24 and the half mirror 25 make up a first light path system, and the mirror 26, the liquid ~ 20 crystal shutter 27 and the half mirror 25 a second light path :~ system. ~he sync signal generator 4, the adder 6, mirrors 22, 23, 26, the liquid crystal shutters 24, 27, hal~ mirror 25 and the TV camera 40 provide a three-dimensional imaging apparatus.
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1 Now, the operation of this configuration will be explained. The TV camera 40 is supplied with a pulse-like signal required for driving the TV camera from the sync signal generator 4. ~lso, the drive pulse, the field pulse and the sync signal for the TV camera produced from the sync signal generator 4 are all in synchronism with each other. The light entering from an ohject through the mirrors 22, 23, and liquid crystal shutter 24 passes through the half mirror 25 and forms an image at the photo-electric transducer section o~ the image pick-up device of the TV camera 40. The light entering from the object through the mirror 26 and the liquid crystal shutter 27, on the other hand, is bent by 90 degree through the half mirror 25 and forms an image at the photo-electric conversion section of the image pick-up device of the TV camera 40. The optical axes of the light path systems 1 and 2 are arranged at a given angle ~ (not shown) against the same object. (The light path systems 1 and 2 correspond to the right and left eyes respectively of the man).
The optical shutter used for the present invention is a liquid crystal shutter long in service life, in which the light interruptions can be controlled by a voltage and the response speed is sufficiently hi~h as compared with the field scanning frequency of the TV camera.
This optical shutter using liquid crystal is substantially of the same construction as the one described with reference to Fig. ~. Since they are also the sa~.e in .
.
1 operation and will be described only briefly.
The li~uid crystal shutters 24, 27 are comprised of deflection plates 10, 11, liquid crystal 12 and transparent electrodes 13, 14 shown in Fig. 6. The liquid crystal shutters 24, 27 are controlled by the drive pulse supplied from the liquid crystal shutter drive circuit. As already explained with reference to Figs. 4 and 6, the liquid crystal shutters pass the light when the field pulse supplied to the AND circuits 1~, 17 making up the liquid crystal shutter drive circuit is at low level. The field pulse is high in level for the first field, and low in level for the second field. As a result, the liquid crystal shutter 27 shown in Fig. 1 passes the light for the first field, and the liquid crystal shutter 24 allows the light to pass for the second field. The light signal representing an object image that has passed the second light path system enters the image pick-up device for the first field, and the light signal carrying an object image that has passed the first light path system enters the image pick-up device for the second field.
The image pick-up device is basically adapted to receive a light signal at the photo-electric transducer section from an object image over the period of one field or one frame, and after accumulating (storing~ ~he signal charges over a period of one field or one frame upon photo-electric conversion, reads out the signal charges thus stored. Thereforel an output signal is delayed by l one field behind the light signal entering the image pick-up surface.
If an image pick-up device or image pick-up tube of linear sequential scan type or an X-Y matrix image pick-up device (MOS image pick-up device) is used for the TV camera 40, it is impossible to obtain a three-dimensional imaging signal for the reason explained below with reference to Fig~ 4. Fig. 4(a) is a diagram illustratively showing the scanning field of the TV camera and the liquid crystal shutter conditions and the potential at point A of the image pick-up surface (photo-electric transducer section) of the image pick-up device of linear se~uential scan type, and Fig. 4(b) a diagram showing the image pick-up surface of an image pick-up device of linear sequential scan type. A light signal enters an image pick-up device after passing through a second light path system (liquid crystal shutter 27) from an object image in the first field, and after passing through a first light path system (liquid crystal shutter 24) in the second field. By way of explanation, the light signal that has passed the first light path system is called the light R, and the one that has passed the second light path system the light L. Explanation will also be made of a case in which an image pick-up device of linear sequential scan type, that is, an image pick-up tube, is used. The potential at point A of the image pick-up surface of the image pick-up tube undergoes a gradual change with time as shown in Fig. 4(a) by storage ~-3~
1 of signal charges, and at a predetermined timing, the signal charges at point A are read out. The signal charges generated at point A, however, are a mixture of a component SR of the signal charges generated by the light passing through the first light path system and the signal charges SL generated by the light passing through the second light path system as obvious from Fig. 4(a). In other words, light from two light path systems are mixed and enter the image pick-up device, and therefore a video signal obtained from the TV camera 40 is blurred, thereby making it impossible to produce a three-dimensional imaging signal. For this reason, the present embodiment uses an image pick-up device for the TV camera 40, which comprises at least a photo-electric transducer and a vertical transfer means or a photo-electric transducer doubling as a vertical transfer ~eans with a signal charge storage section along the extension of transfer by the vertical transfer means. The time of signal charge storage at each photo-electric transducer element of the image pick-up device is kept less than one field of scan period, and images o~ an object from two light path systems entering the image pick-up device are alternately switched for each field by an optical shutter at substantiall~ the same timing as the transfer of signal charges from the photo-electric transducer of the image pick-up device configured as above to the ~ vertical trans~er means.
-; A specific example of an image pick-up device : ,:
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1 usable according to the present invention is an inter-line transfer charge-coupled device (hereinafter abbre-viated as IL-CCD), frame transfer charge-coupled device (hereinafter abbreviated as FT-CCD) or frame inter-line transfer charge-coupled device (hereinafter abbreviated as FIT-CCD). Explanation below will be made about a case using IL-CCD as an image pick-up device. Fig. 2(a) is a diagram showing a schematic configuration of an inter-line transfer charge coupled device (IL-CCD) used with a three-dimensional imaging apparatus according to an embodiment of the present invention. The configuration and operation of the IL-CCD, which is well known, will be briefly described. The IL-CCD, as shown in Fig. 2(a), comprises a light-receiving section A and a horizontal transfer section R. Numeral 41 designates a semiconductor substrate, and the light-receiving section A includes a photo-electric transducer (photo-diode) 42 aligned two-dimensionally, a gate 44 for reading the signal charges stored in the photo-electric converter, and vertical transfer means 43 having a CCD for vertical transfer of signal charges thus read out by the gate. The parts other than the photo-electric converter 42 are optically masked by an aluminum mask (not shown). The photo-electric transducer is separated by a channel stopper 45 in both horizontal and vertical directions. An over-;~ flow drain (not shown~ and an overflow control gate (not shown) are arranged in the vlcinity of the photo-electric transducer. The vertical transfer means 43 is ' .
~3~4~'-3~
1 comprised of a plurality of horizontally-connected polysilicon electrodes ~Vl, ~V2, ~V3 and ~V4 which are connected vertically for each four horizontal lines.
The horizontal transfer section B includes a horizontal transfer means 46 of CCD and a signal charge detector 47. The horizontal transfer means 46 includes transfer electrodes ~Hl, ~H2 and ~H3 connected at intervals of three electrodes in horizontal direction. The horizontal transfer means 46 transfers signal charges transferred thereto from the vertical transfer means toward the charge detector 47. The charge detector 47 includes a well-known floating diffusion amplifier for converting the signal charges into a signal voltage.
Now, the operation will be briefly explained.
The signal charges stored by photo-electric conversion at the photo-electric transducers 42, 42' are trans-ferred to the vertical transfer means 43 from the photo-electric transducers 42, 42' by a signal read pulse ~CH
superimposed on ~Vl and ~V3 of the vertical transfer pulses ~Vl to ~V4 applied to the vertical transfer gate during the vertical flyback period. In the process, if the signal read pulse ~CH is applied to ~Vl, only the signal charges stored in the photo-electric transducer ;~ 42 are transferred to the potential well under the ~V1 electrode, whlle if the signal read pulse ~CH is applied to ~V3, only the signal charges stored in the photo-; electric transducer section 42' are transferred to the potential well under the ~3 electrode.
~3~
1 In this way, a signal charges stored in the photo-electric transducer sections 42, 42' arranged two-dimensionally are transferred to the vertical transfer means 43 upon application of the signal read pulse ~CH.
As a result, if the signal read pulse ~CH is superimposed on ~V1 and ~V3 alternately for every other field, the signal is read out of each photo-electric transducer section for each frame, and therefore the frame storage operation is performed by IL-CCD.
The signal charges transferred from the photo-electric transducer 42 to the potential well under the electrode of ~Vl or ~V3 of the vertical transfer means 43 are transferred to the potential well under the corre-sponding horizontal tansfer electrode of the horizontal transfer means 46 one horizontal line at a time for each horizontal scan period by the vertical transfer pulses ~Vl, ~V2, ~V3 and ~V4. Also, if the signal read pulse ~CH is applied to both ~Vl and ~V3 at substantially the same time during one field period, on the other hand, the signal charges stored in the photo-electric transducer 42 are transferred to the potential well under the ~V1 elec-trode, and the signal charges stored in the photo-electric transducer 42' to the potential well under the ~V3 electrode respectively, so that each photo-electric transducer reads a signal for each field, and thus the IL-CCD performs the field storage operation. In the process, the signal ~ charges transferred to the potential well under the ~Vl :~ and ~V3 electrodes of the vertical transfer means 43 from ::
1 the photo-electric transducer 42 are mixed with siynal charges L for the first ~ield and M for the second field from the photo-electric transducer vertically adjacent thereto in the vertical transfer means, and then trans-ferred one horizontal line at a time for each horizontalscan to the potential well under a corresponding horizontal transfer electrode of the horizontal transfer means 46 by the vertical transfer pulses ~Vl, ~V2, ~V3 and ~V4. The signal charges thus transferred to the potential well under the horizontal transfer electrode are further transferred to the signal charge detection section 47 arranged in horizontal direction by the high-speed horizontal transfer pulses ~Hl, ~H2 and ~H3, and after being converted into a voltage signal, are produced from the image pick-up device as a video signal.
The timing of reading the IL-CCD signal and the timing of driving the liquid crystal shutters in the three-dimensional imaging apparatus according to the present invention, together with the potential change at point Z of the photo-electric transducer in Fi~. 2(a) are shown in Fig. 2~b). Fig. 2~b~ also shows a pule (VBLK) representing the vertical flyback period, a field pulse produced from the sync signal generator 4 of Fig. 1, the signal read timing of IL-CCD, the timing of driving the ~5 liquid crystal shutters, the potential change at point Z
of the photo-electric transducer and the output signal of : the image pick-up device. Signals are read out of the photo-electric transducer to the vertical transfer means ~3(~9~
1 (transfer of signal charges) during the vertical flyback period, and the switching of the liquid crystal shutters substantially coincides with the read timing of the signal from the photo-electric transducer to the vertical transfer means. The timing at which the field pulses are switched also substantially coincides with the timing at which the signal is read from the photo-electric transducer to the vertical transfer means. If the image pick-up device and the liquid crystal shutters are driven at these timings, tlle light signal carrying an object image enters the image pick-up device after passing through the second light path for the first field and after passing through the first light path for the second field respectively.
In the process, the potential at point Z of the~ image pick-up surface of the image pick-up device changes with time slowly as shown in Fig. 2(b), and at a predetermined timing (with a signal read pulse applied to the vertical transfer means from the photo-electric transducer), the signal charges at point Z are transferred to the vertical transfer means. At the same time, the signal charges from the point Z, as obvious from Fig. 2(bj, make up only those produced by the light passed through the first light path or those generated by the light passing through the seo~d light path. Specifically, each pixel of the photo-electric transducer is not entered by light mixture from two light paths. By picking up an image of an ohject maintain-ing ~he drive timings and configuration mentioned above, a video signal due to an object image transmitted through ::
: -- 19 --' : '.
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l the light path system l i9 produced for the first field alterntely with a video signal due to an object image transmitted through the light path system 2 for the second field, thus producing a three-dimensional video signal.
According to the present embodiment, after signal charges of the photo-electric transducer are all transferred (read) to the vertical transfer means, these signal charges are mixed with those an adjacent photo-electric transducer in the vertical transfer means thereby to produce a video signal of field storage from the image pick-up device.
A second embodiment of the present invention will be explained with reference to Fig. 3. The IL-CCD
produces a video signal of field storage without mixing the signal charges of two adjacent photo-electric transducers as explained above. The principle of this operation will be explained with reference to Figs. 2(a~ and 3(b). Fig.
3(a) shows a plse (VBLK) representing the vertical flyback ; period, a field pulse produced from the sync signal generator 4 in Fig. l, a signal read timing of IL-CCD, the driving timing of the liquid crystal shutters, the potential change at point Z of the photo-electric transducer and an output signal of the image pick-up device.
The operation will be explained. In the first field, the signal read pulse ~CH is applied to ~V3, signal charges generated at the photo-electric transducer 42' are transferred to the vertical transfer means at high speed by the high-speed transfer pulse ~VF applied to the vertical transfer pulses ~Vl to ~V4, and after being .
~.3~
1 discharged from the horizontal transfer means, the signal read pulse ~CH is applied to ~Vl. The signal charges generated at the photo-electric transducer 42 are trans-ferred to the vertical transfer means 43, and by the vertical transfer pulses ~Vl to ~V4, transferred to the potential ~ell under a corresponding horizontal transfer electrode of the horizontal transfer means 46 one hori~ontal line after another for each horizontal scan period thereby to effect the horizontal transfer. In the second field, on the other hand, the signal read pulse ~CH is applied to ~Vl, signal charges generated at the photo-electric transducer 42 are transferred to the vertical transfer means 43 at high speed by the high-speed transfer pulse ~VH applied to the vertical transfer pulses ~Vl to ~V4, and after being discharged from the horizontal transfer means, the signal read pule ~CH is applied to ~V3 so that the signal charges generated at the photo-electric transducer 42' are transferred to the vertical transfer means, and by the vertical transfer pulses ~Vl to ~V4, transfe~red to the potential well under a corresponding horizontal transfer means of the hoxizontal transfer means 46 one horizontal line at a time for each horizontal scan period thereby to effect horizontal transfer. This opera~ion produces a video signal of field storage. As seen from Fig. 3(a~, the discharge of unrequired signal charges and the transfer from the photo-electric transducer to the vertical transfer means are effected within a vertical flyback period. By doing so, each pixel of the photo-, ~3~ 4 1 electric transducer is not supplied with a mixture of the light from the two light path systems, with the result that the TV camera ~0 shown in Fig. 1 produces a ~ideo signal of an object image transmitted through the light path system 1 for the first field alternately with a video signal of an object image passed through the light path system 2 for the second field thereby to produce a three-dimensional video signal.
It is possible in the IL-CCD to shorten the storage time of signal charges at the photo-electric transducer as compared with the one-field period. The purpose of shortening the storage time of signal charges is to improve the dynamic resolution of the video signal.
The image pick-up device obtains a video signal by accumulat-ing (storing) the signal charges generated by the lightsignal entering the photo-electric transducer. As a result, .
if the object image moves when signal charges are being accumulated (stored), the resolution of the video signal (called "dynamic resolution") would be deteriorated. If the dynamic resolution is to be improved, it is necessary to shorten the accumulation (storage) time of signal charges.
The present inven~ion remains effective even when the accumulation (storage) time of signal charges is shortened.
The principle of this oper~ation will be explained below with reference to Figs. 2(a) and 3(bj. Fig. 3(b) shows a pulse (VBLK3 representing the vertical flyback period, a field pulse produced from the sync signal ` generator 4 in Fig. 1, a signal read timing for IL-CCD, . . .
l a drive timing for the liquid crystal shutters, the potential of an overflow control gate, the potential change at point Z of the photo-electric transducer and an output signal of the image pick-up device.
An overflow drain (OFD) is provided for the purpose of preventing the blooming phenomenon specific to a solid-state image pick-up device. The amount of charges storable in a photo-electric transducer is set by the potential of the overflow control gate (OFCG~, so that if signal charges are generatd beyond the setting, unrequired signal charges are absorbed into the OFD and discharged from the im~ge pick-up device over the ~FCG.
If the potential barrier of the OFCG is kept low (that is, if the applied voltage to the OFCG is increased) during the entrance of the light signal from the object into the photo-electric transducer (during the vertical flyback period), the signal charges stored in the photo-electric transducer are discharged to the OFD.
The potential at point Z of the photo-electric transducer is thus indicated as shown in Fig. 3(b). This operation permits production of a video signal of a storage time shorter than the field period. By doing sot each pixel of the photo-electric transducer is not irradiated with a mixture of light from the two light paths, and a video signal carrying an object image transmitted through the light path system l for the first field is produced from the television camera 40 alternately with a video signal carrying an object image transmitted through the light path ~3r~
1 system 2 for the second field thereby to produce a three-dimensional video signal.
Explanation is made above about a horizontal-type OFD with OFCG and OFC arranged in the vicinity of the photo-electric transducer section according to the present embodiment. Instead of such an arrangement, however, the OFD may be arranged inward of the image pick-up device as a longitudinal OFD without departing from the spirit of the inventionO ~lso, the principle of operation described with reference to Fig. 3(b) is directly applicable to the case of controlling the storage time by use of a solid-state image pick-up device of frame inter-line transfer type. A solid-state image pick-up device of frame inter line transfer type, which is described in detail in JP-A-55-52675 and will not be described in detail again herein, is basically so configured that a vertical transfer means for storage is arranged on the extension of the vertical transfer means of a solid-state image pick-up device of inter-line transfer type. The purposes of this device are to transfer the signal charges obtained at a photo-diode to the vertical transfer means for storag , and by reading them sequentially, to reduce the generation of smear and to make it possible to set the exposure time of the photo-electric transducer as desired. Setting the exposure time of the photo-electric transducer as desired is equivalent in effect to the process of operation explained with reference to Fig. 3(b) about an example of control of exposure time (storage time) ' ~.3~
1 using a solid-state image pick-up device of inter-line type. In Fig. 3(b?, the light path systems of light entering the TV camera are switched substantially at the same timing as the signal charges are read into the vertical transfer means from the photo-electric transducer. As seen from Fig. 3~b), however, the light path systems may be switched by the li~uid crystal shutters alternatively at a timing of applying a pulse-like voltage to the OFGC, for example. Also, the timing of irradiation of an object image from each light path system to the photo-electric transducer may be substantially equal to the timing of application of a read pulse from the timing of application of a pulse-like pulse to the OFCG. In the case where the storage time of the signal charges in the photo-electric transducer is shorter than the time of one field, it is apparent that the time of the light entering from the TV camera into the two light path systems is not necessarily equal to each other. Specifically, the timing of irradia-tion of an ob~ect image on the photo-electric transducer o~ the solid-state image pick-up device from the light ; path systems may be either equal substantially to the signal storage time or may include the signal storage time.
As explained above,~according to the present invention, images of an object from two light path systems are selected alternately in synchronism with the field scanning of an image pick-up device and imaged three-dimensionally by use of a single TV camera. Instead of ;:
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1 the timings shown in Figs. 2 and 3 according to the present embodiment, the read timing of signal charges and the switching timing of the liquid crystal shutters may be included in the vertical flyback period. Further, a relative displacement, if any, of the read timing of the signal charges and the switching timing of the liquid crystal shutters are allowable practically if not more than the vertical flyback period. The three-dimensional display unit according to the embodiment under consideration is exactly identical to the one explained with reference to Fig. 4 and will not be described.
INDUSTRIAL APPLICABILITY
It will thus be understood from the foregoing description that according to the present invention a three-dimensional imaging apparatus is realized with a single TV camera at a low cost. Further, the fact that a single camera is used for picking up a three-dimensional image eliminates the need of precise adjustment of the angle of the object to the TV camera, etc. and therefore 20 the operation of adjusting the image angle and focal point is greatly facilitated. As a consequence, even a layman can pick up a three-dimensional image for an improved mobility.
:
' ~ .
The operation will be explained. In the first field, the signal read pulse ~CH is applied to ~V3, signal charges generated at the photo-electric transducer 42' are transferred to the vertical transfer means at high speed by the high-speed transfer pulse ~VF applied to the vertical transfer pulses ~Vl to ~V4, and after being .
~.3~
1 discharged from the horizontal transfer means, the signal read pulse ~CH is applied to ~Vl. The signal charges generated at the photo-electric transducer 42 are trans-ferred to the vertical transfer means 43, and by the vertical transfer pulses ~Vl to ~V4, transferred to the potential ~ell under a corresponding horizontal transfer electrode of the horizontal transfer means 46 one hori~ontal line after another for each horizontal scan period thereby to effect the horizontal transfer. In the second field, on the other hand, the signal read pulse ~CH is applied to ~Vl, signal charges generated at the photo-electric transducer 42 are transferred to the vertical transfer means 43 at high speed by the high-speed transfer pulse ~VH applied to the vertical transfer pulses ~Vl to ~V4, and after being discharged from the horizontal transfer means, the signal read pule ~CH is applied to ~V3 so that the signal charges generated at the photo-electric transducer 42' are transferred to the vertical transfer means, and by the vertical transfer pulses ~Vl to ~V4, transfe~red to the potential well under a corresponding horizontal transfer means of the hoxizontal transfer means 46 one horizontal line at a time for each horizontal scan period thereby to effect horizontal transfer. This opera~ion produces a video signal of field storage. As seen from Fig. 3(a~, the discharge of unrequired signal charges and the transfer from the photo-electric transducer to the vertical transfer means are effected within a vertical flyback period. By doing so, each pixel of the photo-, ~3~ 4 1 electric transducer is not supplied with a mixture of the light from the two light path systems, with the result that the TV camera ~0 shown in Fig. 1 produces a ~ideo signal of an object image transmitted through the light path system 1 for the first field alternately with a video signal of an object image passed through the light path system 2 for the second field thereby to produce a three-dimensional video signal.
It is possible in the IL-CCD to shorten the storage time of signal charges at the photo-electric transducer as compared with the one-field period. The purpose of shortening the storage time of signal charges is to improve the dynamic resolution of the video signal.
The image pick-up device obtains a video signal by accumulat-ing (storing) the signal charges generated by the lightsignal entering the photo-electric transducer. As a result, .
if the object image moves when signal charges are being accumulated (stored), the resolution of the video signal (called "dynamic resolution") would be deteriorated. If the dynamic resolution is to be improved, it is necessary to shorten the accumulation (storage) time of signal charges.
The present inven~ion remains effective even when the accumulation (storage) time of signal charges is shortened.
The principle of this oper~ation will be explained below with reference to Figs. 2(a) and 3(bj. Fig. 3(b) shows a pulse (VBLK3 representing the vertical flyback period, a field pulse produced from the sync signal ` generator 4 in Fig. 1, a signal read timing for IL-CCD, . . .
l a drive timing for the liquid crystal shutters, the potential of an overflow control gate, the potential change at point Z of the photo-electric transducer and an output signal of the image pick-up device.
An overflow drain (OFD) is provided for the purpose of preventing the blooming phenomenon specific to a solid-state image pick-up device. The amount of charges storable in a photo-electric transducer is set by the potential of the overflow control gate (OFCG~, so that if signal charges are generatd beyond the setting, unrequired signal charges are absorbed into the OFD and discharged from the im~ge pick-up device over the ~FCG.
If the potential barrier of the OFCG is kept low (that is, if the applied voltage to the OFCG is increased) during the entrance of the light signal from the object into the photo-electric transducer (during the vertical flyback period), the signal charges stored in the photo-electric transducer are discharged to the OFD.
The potential at point Z of the photo-electric transducer is thus indicated as shown in Fig. 3(b). This operation permits production of a video signal of a storage time shorter than the field period. By doing sot each pixel of the photo-electric transducer is not irradiated with a mixture of light from the two light paths, and a video signal carrying an object image transmitted through the light path system l for the first field is produced from the television camera 40 alternately with a video signal carrying an object image transmitted through the light path ~3r~
1 system 2 for the second field thereby to produce a three-dimensional video signal.
Explanation is made above about a horizontal-type OFD with OFCG and OFC arranged in the vicinity of the photo-electric transducer section according to the present embodiment. Instead of such an arrangement, however, the OFD may be arranged inward of the image pick-up device as a longitudinal OFD without departing from the spirit of the inventionO ~lso, the principle of operation described with reference to Fig. 3(b) is directly applicable to the case of controlling the storage time by use of a solid-state image pick-up device of frame inter-line transfer type. A solid-state image pick-up device of frame inter line transfer type, which is described in detail in JP-A-55-52675 and will not be described in detail again herein, is basically so configured that a vertical transfer means for storage is arranged on the extension of the vertical transfer means of a solid-state image pick-up device of inter-line transfer type. The purposes of this device are to transfer the signal charges obtained at a photo-diode to the vertical transfer means for storag , and by reading them sequentially, to reduce the generation of smear and to make it possible to set the exposure time of the photo-electric transducer as desired. Setting the exposure time of the photo-electric transducer as desired is equivalent in effect to the process of operation explained with reference to Fig. 3(b) about an example of control of exposure time (storage time) ' ~.3~
1 using a solid-state image pick-up device of inter-line type. In Fig. 3(b?, the light path systems of light entering the TV camera are switched substantially at the same timing as the signal charges are read into the vertical transfer means from the photo-electric transducer. As seen from Fig. 3~b), however, the light path systems may be switched by the li~uid crystal shutters alternatively at a timing of applying a pulse-like voltage to the OFGC, for example. Also, the timing of irradiation of an object image from each light path system to the photo-electric transducer may be substantially equal to the timing of application of a read pulse from the timing of application of a pulse-like pulse to the OFCG. In the case where the storage time of the signal charges in the photo-electric transducer is shorter than the time of one field, it is apparent that the time of the light entering from the TV camera into the two light path systems is not necessarily equal to each other. Specifically, the timing of irradia-tion of an ob~ect image on the photo-electric transducer o~ the solid-state image pick-up device from the light ; path systems may be either equal substantially to the signal storage time or may include the signal storage time.
As explained above,~according to the present invention, images of an object from two light path systems are selected alternately in synchronism with the field scanning of an image pick-up device and imaged three-dimensionally by use of a single TV camera. Instead of ;:
.~ ' ' .~
~1~3~ 3L~IL
1 the timings shown in Figs. 2 and 3 according to the present embodiment, the read timing of signal charges and the switching timing of the liquid crystal shutters may be included in the vertical flyback period. Further, a relative displacement, if any, of the read timing of the signal charges and the switching timing of the liquid crystal shutters are allowable practically if not more than the vertical flyback period. The three-dimensional display unit according to the embodiment under consideration is exactly identical to the one explained with reference to Fig. 4 and will not be described.
INDUSTRIAL APPLICABILITY
It will thus be understood from the foregoing description that according to the present invention a three-dimensional imaging apparatus is realized with a single TV camera at a low cost. Further, the fact that a single camera is used for picking up a three-dimensional image eliminates the need of precise adjustment of the angle of the object to the TV camera, etc. and therefore 20 the operation of adjusting the image angle and focal point is greatly facilitated. As a consequence, even a layman can pick up a three-dimensional image for an improved mobility.
:
' ~ .
Claims (6)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A three-dimensional image pickup apparatus having a television camera provided with an imaging device which comprises at least photoelectric converting elements and vertical transfer stages corresponding to said photoelectric converting elements, said imaging device reading out signal charges stored in said photoelectric converting elements one or more times in one field by transferring the signal charges simultaneously to said vertical transfer stages, wherein object images transmitted through two optical paths are alternately selected for every field to be picked up, substantially synchronous with the transfer timing of transferring the signal charges from said photoelectric converting elements to said vertical transfer stages.
2. A three-dimensional image pickup apparatus according to claim 1, wherein, when the object images through two optical paths are alternately selected for every field to be picked up, the storage period of the signal charges in said photoelectric converting elements is equal to or shorter than the period of projecting the selected object image onto the photoelectric converting elements, and the storage period of the signal charges in the photoelectric converting elements is inside the period of projecting the selected object image onto the photoelectric converting elements.
3. A three-dimensional image pickup apparatus according to claim 1, wherein, in the case where the photoelectric converting elements functions also as the vertical transfer stages, the imaging device comprises a storage site for the signal charges on the extension of each vertical transfer stage in its transferring direction.
4. A three-dimensional image pickup apparatus according to claim 1, wherein the imaging device transfers the signal charges stored in the photoelectric converting elements to the vertical transfer stags, mixes the signal charges from two vertically adjacent photoelectric converting elements with each other, and then performs the vertical and horizontal transfer to produce an output.
5. A three-dimensional image pickup apparatus according to claim 1, wherein the imaging device picks up an image in the manner that, among the signal charges accumulated in the photoelectric converting elements by projecting an object image, the signal charges which have been obtained by the photoelectric conversion before a predetermined period are previously eliminated by the photoelectric converting elements and the vertical transfer stages, thereby equivalently restricting the projection of the object image onto the photoelectric converting elements, to or within one field period.
6. A three-dimensional image pickup apparatus according to claim 1, wherein each optical path comprises a plurality of mirrors and a shutter for blocking light, and alternately selects the object images obtained through said optical paths using said shutter in synchronism with the field scanning operation of the television camera.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000596352A CA1304494C (en) | 1989-04-11 | 1989-04-11 | Three-dimensional imaging apparatus |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000596352A CA1304494C (en) | 1989-04-11 | 1989-04-11 | Three-dimensional imaging apparatus |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1304494C true CA1304494C (en) | 1992-06-30 |
Family
ID=4139894
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000596352A Expired - Lifetime CA1304494C (en) | 1989-04-11 | 1989-04-11 | Three-dimensional imaging apparatus |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1304494C (en) |
-
1989
- 1989-04-11 CA CA000596352A patent/CA1304494C/en not_active Expired - Lifetime
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