EP0287641A1 - Modified scan sub sampled high definition television - Google Patents

Abstract

The described high definition television system is compatible with existing standards. The imaging device (28) has a scanning circuit (22) which causes jump scan subsampling of a plurality of different scanning position variations from the standard imaging device. Sweep position variations are in a triangular configuration. The scanning positions are offset and require three frames to build the high definition image. The receiver can use a memory (192) and a motion comparator (213) to switch between a low temporary and high spatial resolution for stationary objects and a low temporary and high spatial resolution for moving objects. In addition to the standard horizontal (60) and vertical (62) scan generators, the scan circuit (22) includes generators (64, 66, 68, 76, 78) with added output (70, 72, 74, 80 , 82) to the standard scan output to cause the scan to jump between the scan positions and thereby cause the triangular subsampling configuration.

Description

"Modified Scan Sub Sampled High Definition Television"

Field of the Invention The field of the invention pertains to television transmitter and receiver systems and, more generally, also to electrical image transmission and receiver systems.

Background of the Invention Television has developed according to certain standards having broad geographical applicability.

This, of course, has been necessary to achieve the goal of compatability between transmitter systems and receiver systems communicating over regulated channels of information which are limited in number.

By way of example, the NTSC (National Television System Committee) Standard has obtained in the United States since 1941. Such standard calls for transmission and reception of 525 horizontal lines of information, to cover a full frame of a picture, in two fields of 262.5 lines each. The two fields are inter¬ laced with odd-numbered lines being transmitted seriatum, as a first field for the frame, even-numbered lines seriatum as a second field, then the odd-numbered lines seriatum again, etc. The transmission of each field in 1/60th of a second (1/59.94th of a second for color), and thus of a full frame in 30th of a second (slightly slower for color), is adapted to avoid or

SUBSTITUTE SHEET minimize the appearance of flicker as the fields are received and their content changes.

Still referring to the NTSC Standard, the bandwidth for a channel, which essentially then determines the amount of information (in effect, the number of possible variations) along each horizontal line, has been set at about 4.2 megaHertz for the light and dark variations along the line, and at a total bandwidth allocation for the channel of 6 megaHertz. The additional capability within the 6 megaHertz provides for sound transmission and for reinforcing the strength of the light and dark variation information (through a vestigial lower side-band of the signal carrying that information). It also provided, in 1953, the capability to -modify the NTSC Standard, existing at that time, to incorporate within the same 6 megaHertz-channel, the capability for the type of color transmission and reception which now exists in the United States and other NTSC countries.

Of course, the spatial definition for the NTSC system has been determined by the number of horizontal lines in a frame (indicating the definition in the vertical direction) and the capability for variation along each horizontal line (as limited by bandwidth restrictions).

Referring to the vertical direction, the starting point for the degree of vertical definition is the 525 line divisions for a picture frame. However, the information along 42 of these lines is not active in creating images on a picture tube, but is reserved as the "vertical interval" between the termination of

SUBSTITUTE SHEET image scanning at the bottom and re-starting at the top. This interval is used for such matters as certain timing aspects, scan return, and the transmission of non-image data such as test signals and close-captioned services. Thus, the measure of vertical definition is reduced to 483, derived from the 483 active lines. Because of various systemic limitations, in connection with the electronics involved and the human visual system, the typical observable definition in the vertical direction (observable according to a test pattern wedge) in fact is generally the equivalent of about 330 lines.

Concerning the definition in the horizontal direction for the NTSC Standard, and referring back, to the vertical starting point of 525 horizontal lines and the timing, for color, of 1/59.94th second for each of two interlaced fields, one can calculate approxi¬ mately 15,734 lines per second, or about 63.6 micro- seconds available per line. Considering this time availability per line, vis-a-vis the bandwidth available for indicating light and dark variation, which is 4.2 megaHertz (or 4.2 cycles per microsecond), one can calculate approximately 267.12 cycles per line.

^•It is then, for purposes of television, generally considered that a fair measure of the capa¬ bility for light-dark variation along the horizontal lines, is the number of half cycles which can fit along

SUBSTITUTE SHEET the time for a line, or about 534. This is rather comparable to the 525 horizontal lines per frame starting point for the vertical resolution. However, a portion of the time available per line is required for the signal which controls the timing of the onset of the line (the synchronizing of the line) and for the electronic circuits involved in controlling the image scanning along the line to "settle" before onset. As a result, only about 52.5 microseconds of the 63.6 microseconds available for each line, shows up on the screen. This then corresponds to about 440 half cycles.

Using these numbers, 483 for the vertical and 440 for the horizontal, for a picture tube screen having a height H and a width W, one might then conveniently define the vertical resolution as (1/483) X H and the horizontal resolution as (1/440) X . The "aspect ratio", the ratio of W to H, in the U.S. and a number of other countries, -has.been generally set at 4:3.

In various countries of the world having different standard^'s than the NTSC Standard, rather comparable situations exist. Specifically, such systems, depending upon the number of horizontal lines they employ, and the bandwidth available per channel, generally contain comparable limitations as to the degrees of definition embodied in the system. Stated another way, the NTSC and other systems embody certain assumptions and limitations as to the degree of detail provided in transmitting and receiving images.

SUBSTITUTE SHEET The NTSC Standard, and other standards in various countries, have provided the basis for uniform, widespread television systems in such countries. They also have been the foundations for tremendous amounts of investment, for example by the public in television receivers adapted for the standard adopted. Thus, although the technological capability for much higher definition systems has developed, the "infrastructure" built into, e.g., receivers, makes it extremely difficult to adopt higher definition systems.

For example, a form of higher definition system based upon about 1,030 horizontal lines being active in defining images, a 30 megaHertz channel bandwidth, a 16:9 aspect ratio, and the transmission of sixty fields per second with two interlaced fields, has recently received a great deal of positive attention. However, the implementation of anything approaching- - that system, for example within the confines of the NTSC Standard and the installed receiver equipment based on that standard, is not feasible. Thus, the desire to move toward higher definition television certainly exists, but the development of new, higher definition systems falls short of what is required, in practice, to move toward higher definition on a wide¬ spread basis in a country such as the United States. Simply stated, such higher definition systems are contrary to well-ingrained standards on ihe basis of which tremendous economic investments have been made.

SUBSTITUTE SHEET Certain extremely limited ways of ad¬ dressing the desire for greater definition have been the subject of substantial consideration and effort. For example, it was noted that certain factors tend to decrease the effective vertical definition, indicated by the number 483, to about 330. One of these factors is the utilization of the two interlaced field scheme. To address this, by storing transmitted information in a receiver, one can present it for display at a rate independent of its reception. For example, one need not necessarily present it in an interlaced fashion and, further, one can present it at a rate faster than, e.g., thirty frames per second (albeit, in a more repetitively refreshed display than would otherwise occur). An approach such as this has been found to present the capability for increased vertical defini¬ tion of in the range of 25%. Of course, horizontal definition, which is limited by the channel bandwidth, is not affected.

Thought has also been given to, for example, dedicating an additional channel to a transmission so that more information (more definition) can be incorpo¬ rated into the transmission. Of course, this approach carries the unquestioned disadvantage of using valuable bandwidth to achieve the desired result. Would one rather receive two distinct programs or one program with a better picture?

SUBSTITUTE SHEET Nevertheless, the just-mentioned approaches, embodying the storage technique and the additional channel, are compatible with, for example, maintaining the NTSC Standard, and such approaches, similarly, can be employed in areas of the world having different but analogous standards to the NTSC Standard. As indicated, however, they have severe limmitations.

An attempt to bring about wholesale adoption of a straightforward high definition system, such as the 1,030 line one described above, has the extreme disadvantage of incompatibility with current standards. Other higher definition systems, although still incompatible, are "less incompatible" with existing standards. For example, one of these, known as the NHK Muse approach, provides more spatial definition (more spatial detail) in return for less time definition (fewer changes over time). In so doing, it provides for the transmission of motion vectors from, the trans- itter, during the vertical interval, to indicate amounts of movement, in order to control switching between higher spatial definition and higher time definition .where the transmitted motion vectors indicate such is desirable.

Turning to various specific background items, Songer, U.S. Patent No. 4,589,012, adopts a sinusoidal oscillation of conventional trace lines in order to cover more vertical area during horizontal tracing. An oscillation frequency exceeding the normal NTSC band¬ width is stated to be preferred. Thus, in fact, one

SUBSTITUTE SHEET would expect the information from the oscillatory movement to be filtered out if transmission were over a normal NTSC channel. However, a lower oscillation frequency is noted as a possible alternative.

Such oscillatory motion, over a channel of sufficient bandwidth, does provide more vertical information and, thus, more vertical resolution. However, despite what might otherwise be adverted to in the patent, increased horizontal information and resolution cannot be obtained from the form of tracing which is provided. Also, by way of example, trans¬ mitted signals for horizontal edges of objects, or horizontal image lines, if received by a receiver with conventional tracing, would be displayed as dotted lines. In Songer, as is stated therein, the provision of additional channel bandwidth is clearly preferred in the context of the oscillatory tracing which is provided.

Toulon, U.S. Patent Nos. 2,479,880, 2,940,005 and 3,065,294, also, are at least in part directed to various tracing techniques.

Specifically, Toulon adopts the approach of defining configurations of surface areas and then exploration, transmittal, reception and display according to patterns of such areas. The configura- tions are, as described by Toulon, orthogonal configurations.

SUBSTITUTE SHEET By way of example, in the Toulon '880 patent, one pattern calls for skipping every other horizontal area to provide, in effect, two interlaced vertical fields. Another exemplary alternative pro- vides a skipping of every other horizontal area, but offset between adjacent lines to provide checkerboard interlace patterns. Carrying the technique to a more extreme point, and further by way of example, blocks of sixteen surface areas are defined, numbering corre- spending areas in each block from 1 to 16. Then the blocks can be filled in by exploring all number 1 areas first, all number 2 second, etc.

Also addressed is the technique of bringing the electron tracing beam to near shut-off between the jumps from one surface area to another, making it more difficult for the eye to follow the tracing patterns — a desirable result.

In the Toulon '005 and '294 patents, the technique of following different orders of the numbered surface areas, for different blocks of such areas, is focused on. For example, considering blocks of four surface areas, and moving along horizontal groups of such blocks, the number 1, 2, 3 and 4 areas may be applicable to different surface areas in different blocks.

These latter two patent disclosures, also, are largely directed to adaptation of the indicated techniques to color. Apparently, the adaptation

SUBSTITUTE SHEET involves a consideration of areas of different color phosphors and of the order of their exploration for transmission and reception. Further, the potential for changing the order followed, at different times, is addressed as a way of scrambling a transmission. Then, a receiver not having information as to the order of the exploration will receive a scrambled signal. This provides for secrecy of transmissions from those one does not wish to receive them.

Deutsch, U.S. Patent No. 3,309,461, and S. Deutsch, "Visual Displays Using Psuedorandom Dot Scan", IEEE Transactions on Communications, Vol. Com.-21, No. 1, January, 1973, pp. 65-75, bears some relationship to the Toulon patents.

The Deutsch paper is directed to attempting to make, e.g., dots, which are scanned in fields, appear as if they are were scanned in a completely random fashion, although such, of course, is not truly the case. This is called "pseudorandom" scanning. A "hybrid" of the pseudorandom scanning is also addressed. The hybrid approach is somewhat less random than the pseudorandom approach. Both are disclosed as essen- tially directed to specialized equipment, enabling slow repetition rates for the fields, to provide for narrow channel bandwidths.

The pseudorandom technique derives the signals for the scanning by the electron beam at the transmitter and receiver, from summing various forms of square waves. The hybrid technique employs a basic, coarse signal similar to a television sawtooth tracing signal, and adds a signal incorporating triangular forms to the coarse signal. This provides, as a sum signal, a sawtooth signal broken by level areas. Then, to that signal, additional forms of square wave signals are added. The electron beam may be gated on at level signal areas and, otherwise, maintained off.

The attempt to "mimic" randomness is to provide the appearance of a lack of any regularity to the order of the dots which are in the fields which are repetitively scanned to provide a complete frame.

The Deutsch patent is generally directed to the same subject matter as the Deutsch paper. The patent emphasizes that the basic idea is the apparent randomness of choice, for each field, from one of a large set of dots for a small portion of a 'screen. :: These screen portions containing dots, of course, are related to Toulon's blocks of surface areas. In the patent, Deutsch notes that there is no requirement that such screen portions be square or rectangular shaped (see Figures 23-27).

B. Wendland, "Extended Definition Television With High Picture Quality", Video Picture of the Future, SMPTE, Scarsdale, New York, 1983, pp. 57-71, exhibits some awareness and sensitivity to the difficulty of taking advantage of higher resolution technology under contemporary television standards which have

SUBSTITUTE SHEET developed. In the course of addressing this, Wendland apparently incorporates the idea of storage of display signals so that, e.g., they can be read out at a different rate than they are read in, and, also, the technique of time plexing (interweaving signals in time) for offset fields of apparently high resolution information. Such fields, termed "orthogonal", apparently may be sampled by moving from a sample point on one line of a field to a sample point on the next line for the field below and then, up diagonally back to the next horizontal sample point on the first line. Such techniques, apparently, are intended to make higher vertical resolution information available in a standard time frame previously adopted for less resolution.

As part of the background for his techniques, Wendland focuses on certain areas of trade-off between resolution as to detail of display areas and resolution in time. Thus, a display may emphasize time resolution (e.g., provide two interlaced fields during the time for a frame) when such is deemed appropriate and higher display area resolution (scanning lines in order without any interlace in the time for a frame) where that is appropriate. In considering where one or the other is appropriate, Wendland adverts to considering amounts of movement between frames, such as a trigger based on a movement, of greater than two surface divi¬ sions from one frame to the next. In the context of the considerations discussed in Wendland, greater bandwidth, nevertheless, apparently is focused on as a mechanism for increasing resolution in the horizontal direction.

SUBSTITUTE SHEET as opposed to the other techniques for enhancing resolution in the vertical direction.

Nakashima, et al., U.S. Patent No. 2,093,157, generally indicates that continuously traced lines may be disagreeable as opposed to more discon¬ tinuous tracing. As indicated above, that has also been well recognized in the context of considerations addressed in Toulon and Deutsch.

The present subject matter comprehensively and practically addresses the incorporation of higher spatial definition television into a context having ingrained requirements which were adopted for lower spatial definition television. Such requirements, for example, are incorporated in signal and channel re¬ quirements for the transmitted television signals and in the tremendous investment in installed lower definition receivers. It provides the capability for higher definition transmitters and receivers while preserving the usefulness of lower definition receivers and substantially preserving well-entrenched television signal requirements.

In accomplishing this, the invention provides, in a transmitter system, scanning according to a number of different scanning position variations of the scanning position arrangement previously adopted for the lower definition receivers. In higher defini- tion receiver systems, which can receive the same signals fro the transmitter system as the lower

S definition receiver systems, but which display them with higher spatial definition, the scanning then corresponds to that in the transmitter system.

The higher spatial definition receiver systems, also, can switch between higher spatial definition with lower time definition, and lower spatial definition with higher time definition, according to certain techniques. These techniques incorporate the providing of spatial groups of scanning positions and, in certain circumstances, changing the display information for the members of a group to correspond to that for one member of the group which undergoes a significant degree of change.

In providing the capability for higher spatial definition within the above-indicated context, the subject matter herein provides for different scanning position variations together forming succes- sive groups of scanning positions, in triangular configurations, along straight, sideways-extending lines. Such triangular configurations then have the bases for the configurations alternately oppositely oriented along such lines.

By way of example, in the United States where the NTSC Standard for television is well- ingrained, the requirements of the Standard may be substantially maintained.

Summary of the Invention In accordance with the invention, a tele¬ vision transmitter system is adapted for concurrently generating and transmitting video signals for a rela¬ tively higher spatial definition television receiver system and a relatively lower spatial definition television receiver system. The transmitter system includes: imaging apparatus to establish images for transmission to the receivers; scanning apparatus, for the imaging apparatus, for scanning a plurality of different scanning position variations of a scanning position arrangement for the lower definition receiver, such different scanning position variations sub¬ stantially corresponding to scanning position arrange¬ ments for the higher definition receiver? and apparatus for generating and transmitting video imaging signals for the plurality of different scanning position variations, such signals adapted to cyclically define the substan¬ tially corresponding scanning position arrangements for the higher definition receiver and to, concurrently, repetitively define the scanning position arrangement for the lower definition receiver.

In accordance with other transmitter aspects of the invention, an electrical visual image transmis¬ sion system includes: imaging apparatus to establish images for transmission; and apparatus for electroni- cally scanning, for the imaging apparatus, a plurality of different scanning position variations of a scanning position arrangement on substantially straight lines, wherein the plurality of different scanning position variations form successive groups of scanning positions, in substantially triangular configurations, along substantially straight lines. These triangular con¬ figurations then have the bases for the configurations

SUBS alternatively substantially oppositely oriented along the substantially straight lines.

In a television transmitter system embodiment, in accordance with the above and with other aspects of the invention, the scanning apparatus includes: apparatus for generating, for the scanning apparatus, successive leftward scan excursions and alternating upward and downward scan excursions with respect to the scanning for the relatively lower definition receiver system to provide a first one of the plurality of different scanning position variations; apparatus for generating, for the scanning apparatus, successive rightward scan excursions and alternating upward and downward scan excursions with respect to the relatively lower defini¬ tion receiver system, such upward and downward excur¬ sions being substantially 180 degrees out of phase with the upward and downward excursions for the first scanning position variation, to provide a second one of the plurality of different scanning position variations; and apparatus for generating, for the scanning apparatus, alternating upward and downward scan excur¬ sions with respect to scanning for the relatively lower definition receiver system, to provide a third one of the plurality of different scanning position variations. In addition: the video imaging signals for the plurality of different scanning position variations are substantially in accord with the NTSC Standard for transmission over a channel substantially in accord with the NTSC Standard; and the scanning apparatus of the transmitter system includes apparatus to generate

SUBSTITUTE SHEET cycle synchronizing markers to mark cycles of the video imaging signals for the plurality of different scanning position variations. Additionally, the substantially straight lines along which the successive groups of scanning positions, in substantially triangular configurations, which are referenced above, occur, are oriented in a sideways direction.

In accordance with receiver aspects of the invention, a relatively higher spatial definition television receiver system for transmitted video imaqing signals which are concurrently for a relatively lower spatial definition receiver system, and an electrical image receiver system, incorporates display apparatus to display images, scanning apparatus, a plurality of different scanning position variations and a relationship to the NTSC Standard, corresponding to the above-described aspects for a television trans¬ mitter system and an electrical visual image transmission system.

In addition, in accordance with spatial versus time definition aspects of the invention, a television receiver system is adapted to provide different degrees of spatial and time definition for different parts of display images. The receiver system includes: display apparatus to display images; apparatus for scanning, for the display apparatus, a plurality of different scanning position arrangements, wherein such different arrangements have identified groups of scanning positions, each including a scanning

SUBSTITUTE position from each of the arrangements; memory apparatus for receiving and storing groups of video imaging signals for the groups of scanning positions; comparator apparatus to compare update video imaging signals for scanning positions of the groups with signals for such positions from the stored signals, to determine degrees of change between such update signals and such compared signals; and apparatus for changing signals for scanning positions of such groups, from the stored signals, when the comparator apparatus indicates degrees of change for other positions of the groups which exceed defined levels of change. The memory apparatus includes: a display memory for receiving and storing groups of video imaging signals for the groups of scanning positions, for purposes of generating the display images and for the indicated changing by the changing apparatus; and a pre-display memory for receiving and storing groups of imaging signals for the groups of scanning positions, wherein these stored signals are for purposes of the indicated comparing by the comparing apparatus.

Brief Description of the Drawings Figure 1 shows a television communication system having a transmitter system for transmission to a group of receiver systems having relatively higher spatial definition reception and also to a group of receiver systems having relatively lower spatial definition reception.

Figure 2 is a block diagram of the video portion of the television transmitter system of Figure

SUBSTITUTE SHEET 1 and of the video portion of a higher definition television receiver system of Figure 1. However, the receiver system portion as generally shown in this block diagram, apart from relatively minimal variations which are made apparent in connection with the detailed discussion of Figures 3 and 4, is also generally applicable to the relatively lower definition television receiver systems of Figure 1.

Figure 3 is a more detailed block diagram of a part of Figure 2, at the transmitter system side.

Figures 4(1) and 4(2) is a more detailed block diagram of a part of Figure 2, at the receiver system side.

Figure 5A through M show, in somewhat schematic form, electrical signals for scanning position control at various points in Figures 3 and 4.

Figures 6A and 6B somewhat schematically show scanning position variations for the transmitter and receiver systems of Figure 2, according to the scanning provided by the elements of Figures 3 and 4, along with the traditional scanning position arrangement for the lower definition television receiver systems of Figure 1.

Figures 7A and 7B somewhat schematically further illustrate, on a larger scale than Figures 6A and 6B, aspects of Figures 6A and 6B.

Figure 8 is a flow diagram showing the operation of a portion of Figure 4. Figure 9 somewhat schematically illustrates the form of video imaging signals transmitted by the transmitter system of Figure 1 and received by the receiver systems of Figure 1.

Detailed Description By way of introduction, and referring to Figure 1, there is provided a television transmitter system 12 for both relatively higher and relatively lower spatial definition television communication.

Thus, the transmitter generates and transmits signals, represented by the signal waves 14, which are meant to provide relatively higher spatial definition reception to a large number of relatively higher definition television receiver systems 16, numbered with the even numbers 2 through "N", and concurrently, to provide relatively lower spatial definiton^' reception to a large number of relatively lower definition television receiver systems 20, numbered with the odd numbers 1 through "M". The relatively lower definition receiver systems are conventional systems designed and built according to conventional standards and techniques to receive signals according to channel and signal requirements which were developed for the lower spatial definition type of reception. The transmitter 12 can replace the type of conventional transmitter that was specifically designed and developed with the lower definition requirements and receivers in mind. Thus, the signals which it generates and transmits are compatible with the provision of the relatively lower spatial definition type of picture provided by the relatively lower definition receiver systems 20.

SUB_STITUTE SHEET However, at the same time, these signals provided by the transmitter 12 are compatible with the relatively higher definition television receiver systems 16. Thus, by way of example, the transmitter 12 might be for a station in a large metropolitan area and the receiver systems might be systems in a large number of homes in the metropolitan area within the reach of the station.

Figure 2 shows, in block diagram form, the video portion of the transmitter system 12 and the video portion for one of the higher definition receiver systems 16. For convenience of description and ease of understanding, all of the higher definition receiver systems will be assumed to be identical.

The basic block diagram format of Figure 2, in fact, is also in accordance, or at least nearly in accordance, with the video portions of many conventional transmitter systems for lower definition operation, and many conventional receiver systems for lower definition operation, which are currently in use.

In Figure 3, the transmitter scanning and synchronizing circuits 22 of Figure 2 are shown in additional detail. This more detailed breakdown of such circuits shows changes over a typical form of such circuits for a conventional transmitter which act to provide the higher spatial definition capability of the transmitter 12.

Similarly, in Figure 4, the more detailed block diagram of the receiver-scanning circuits 24 of Figure 2, reveals the changes over a typical conven¬ tional form for such circuits, incorporated into the higher definition receiver systems 16. In addition, another portion of Figure 4, showing the receiver luminance signal treatment circuits 26 of Figure 2, in additional detail, shows the changes over a typical, conventional form of such circuits, which provide a capability, related to the higher spatial capability of the receiver systems. This is the capability to vary between a relatively higher spatial definition format (with lower time definition) and a traditional, lower spatial definition format (with higher time definition) for different areas of the images such a receiver is displaying according determinations which the luminance signal treatment circuits make when receiving and processing the information for such displaying. In regard to this. Figure 8 is a flow diagram for the process which is followed by that portion of Figure 4 in making such determinations and carrying out what the determinations call for.

In Figure 5, somewhat schematic forms of electrical signals provided by the transmitter and receiver scanning circuitry of Figures 3 and 4 is shown. This is in accordance with the fact that the scanning for the transmitter and for the higher defini¬ tion receiver, to provide the relatively higher spatial definition performance, correspond to one another. These signals also reveal the differences over a typical, conventional form for scanning signals in conventional .lower definition transmitters and receivers.

SUBSTITUTE SHEET In Figure 6A, there is somewhat schematically illustrated, three different scanning position varia¬ tions (represented by the dots numbered 1, 2 and 3) which are followed by the transmitter 12 and higher definition receivers 16 for higher definition opera¬ tion. These are variations of a typical, scanning position arrangement for the conventional, relatively lower spatial definition receivers 20 (as well as for a corresponding lower definition transmitter). In acordance with this, in Figure 6B there is somewhat schematically shown the typical, conventional form for the horizontal scan lines and the scanning position arrangement for the lower definition receivers (as well as for a corresponding lower definition transmitter). In Figures 7A and 7B, the contrast between the dif¬ ferent scanning position variations and the conven¬ tional scanning position arrangement is further revealed in additional detail.

Figure 9 shows, again somewhat schematically, the form of the video portion of the signals which are transmitted by the television transmitter system 12 to the higher definition receiver systems 16. and the lower definition receiver systems 20 — these video signals including the signals which define the images which are to be displayed and which are sent to control the timing of the receivers, maintaining such timing in synchronism with the transmitter. The accompanying sound signals transmitted by the transmitter and received by the receivers, of course, are sent and received at the same time as the video signals.

SUBSTITUTE SHEET However, such audio aspects form no part of the present invention and the present invention is adapted for use with the audio aspects now present in conventional television- transmitters and receivers and for operation without change in the audio portion of the signals which are transmitted.

As previously indicated, the present subject matter is applicable to implementing higher spatial definition transmission and reception into communica¬ tions networks and channels that were developed for lower definition operation under a variety of different standards. However, for ease of description and convenience of understanding, it will be assumed that the NTSC Standard, as explained in the "Background of the Invention" section, now applicable in the United States, is the context for the detailed description of the apparatus and operation thereof herein. The channel bandwidth, numbers of horizontal lines, inter- lacing of two fields, one for odd lines and one for even to form a complete frame, and the conventional horizontal and vertical spatial definition aspects, as explained in that section, in the context of the NTSC Standard, thus, are assumed to be the characteristics for the lower definition system which the television transmitter 12 and the relatively higher definition receivers 14 are adapted to fit in with.

Turning to Figure 2, the transmitter imaging device (or camera image unit) 28 of the television transmitter system 12 is a conventionally-implemented

SUBSTITUTE SHEET four electron beam color device which establishes images for purposes of transmission under the control of a camera unit operator. In accordance with standard forms of such devices, the imaging device of Figure 2 provides the images for transmission on four different surfaces, and scans each surface, in synchronism, with an electron beam, according to the control of the scanning and synchronizing circuits 22, to provide electrical signals representative of characteristics of the images shown on the surfaces. The four forms of the images established on the four different surfaces represent, in one case, the variation in darkness and lightness (black or white) content of what is shown, in a second case, the color red content in what is shown, in a third case, the color green content, and, finally,^: the color blue content. These four different represen¬ tations of the same images, on four separate surfaces, when scanned in synchronism under the control of the scanning and synchronizing circuits 22, provide a luminance electrical signal, typically represented by the letter "Y", representative of the degree of light¬ ness or darkness, and red, green and blue electrical signals, typically labelled "R", "G" and "B", repre¬ sentative of the amount of red, green and blue, respectively, of what appears in the images as the scanning proceeds. It will be readily apparent that, as alternatives to the four electron beam color imaging device 28, conventionally implemented three or fewer electron beam color imaging devices could readily be employed with conventionally implemented circuits that are able to derive the luminance and three color electrical signals from a lesser number of beams. 25A

The luminance signal treatment circuits 26 and color signal treatment circuits 30 of Figure 2 are wholly conventional. Thus, they provide the normal pre-processing of the luminance signal and of the red.

SUBSTITUTE SHEET 26

green and blue signals, respectively, which is required before signals carrying the luminance and color informa¬ tion are combined with synchronizing signals from the scanning and synchronizing circuits 22 in the composite video formation, control and amplifier circuits 32.

These composite video, formation, control and amplifier circuits act on the incoming synchronizing, luminance and color signals, including such operations as mixing and amplification, to provide a composite video signal ready for transmission by a conventional video trans¬ mitter antenna 34. Their action here is totally in keeping with normal operation by standard circuits of this type with one minor variation implemented by a simple, conventionally-implemented modification of such standard circuits. This minor variation can be readily understood, and thus is explained below, in connection with Figure 3.

Because of the relatively higher spatial definition capability required for the imaging device 28, that device should have a relatively higher defini¬ tion capability than, for example, television trans¬ mitter systems which are most commonly in use. However, the adaptation of generally the same form of device for higher definition operation is readily accomplished in accordance with conventional, comonly employed cathode ray tube apparatus and techniques. The major change over the form for the most commonly used transmitters is a capability for higher beam focus (a smaller electron beam to scan the surfaces on which the images are established and generate the color and luminance signals). Alternatively, an implementation employing 27

conventional techniques which have been specifically developed for high definition performance, e.g., of the 1,030 horizontal line per frame and 30 megaHertz channel type, as referred to in the "Background of the Invention" section, can be readily employed.

In sum, the detailed aspects of the scanning and synchronizing circuits 22 and the scanning position variations for the scanning which they control, as more fully indicated in Figure 3, Figures 5A through 5M, and in Figures 6A and 6B and 7A and 7B, is the subject matter relating to the transmitter 12 substantially focused on herein.

The broad outlines of the video aspects of the higher definition television receiver systems 16, as shown in Figure 2, should also be initially considered.

Similarly to the situation for the video aspects of the television transmitter system 12, which are shown in Figure 2, the video receiver antenna 36, the tuner 40, the composite video amplifier, detector and separation circuits 42 and the color signal treat- ent circuits 44 are in accordance with, or at least nearly in accordance with, the same apparatus for lower definition television receiver systems of the type which are most commonly found and available. Also similarly, the display device 46, for example a picture tube, is readily conventionally implemented. To provide for the higher than traditional definition capability, all that is required is a high quality device according to the basic form 28

of the cathode ray type picture tubes which are most commonly used and employed.

The display device 46 shown is of the traditional type of color picture tube which has three electron beam guns which scan across the phosphor- covered surface of the tube, in synchronism. As shown, and as is typical, the color input signals for control¬ ling the three electron guns which control the red, green and blue content, are provided to the display device in the form of a signal representative of the red level minus the luminance level ("R-Y"), a signal representative of the green level minus the lumi¬ nance level ("G-Y"), and a signal representative of the blue level minus the luminance level ("B-Y"). In controlling the red, green and blue electron guns, the pure luminance-signal and the signals carrying the color information are employed together in the opera¬ tion of the electron guns. As indicated, this is an extremely common and well-known approach utilized in connection with conventional color signal treatment circuits and conventional display devices.

The display device, as is conventional, has phosphors providing red, green and blue, upon excita¬ tion by the respective red, green and blue electron beams. These phosphors, in probably the most typical form of color display device, are densely distributed as sets of, in effect, three phosphor dot-like elements, one per color, over the display area excited by the beams. According to another common format, the phosphors may be in sets of

SUBSTITUTE SHEET 29

thin vertical strips respectively formed of phosphor material for the three respective colors. At any rate, for each relatively tiny area of the excited display surface, a number of sets of dot-like elements or strips typically are present for excitation. This, of course, is to provide adequate blending of the red, green and blue given off by the phosphors to "fool" the human visual system over relatively tiny display areas.

In sum, and similarly to the situation for the transmitter, the receiver scanning circuits 24 and the scanning position variations which they provide (corresponding to such variations for the transmitter scanning and synchronizing circuits 22), as revealed in substantial detail in a portion of Figure 4, Figures 5A through 5M, and in Figures 6A and 6B and 7A and 7B, are one area to be focused on in substantial detail. In addition, a portion of the luminance signal treatment circuits 26, as revealed in Figures 4 and 8, is another area of focus.

Before moving from Figure 2, it might be noted in passing that a conventional transmitter power supply 48 and a conventional receiver power supply 50 are shown to receive AC line power and provide DC power signals Pt and Pr for the transmitter elements and re¬ ceiver elements, respectively. However, as is now commonplace, internal crystal-based, rather than AC line power-based, timing is assumed to be incorporated within the.-transmitter scanning and synchronizing cir¬ cuits 22 and the receiver scanning circuits 24 for use, in conventional fashion, in the timing of the scanning and synchronizing signals provided by such circuits. 30

Turning to Figure 3, a synchronizing generator 52, wholly conventional, is of a type which is commonly available at transmitter station locations. It provides the timing signals for controlling the timing of various of the other elements. Among these other elements are a horizontal trigger generator 54 and a vertical trigger generator 56. These, again, are conventional — the first employed to generate timing signals, from the input of the synchronizing generator, for controlling the horizontal scanning in the trans¬ mitter and the second for generating timing signals, from the synchronizing generator input, to control the vertical scanning in the transmitter. The terminology "horizontal", of course, is traditionally used to refer to the sideways scanning across the scanned surface. This is the case even though such scanning is typically slightly downwardly tilted as it proceeds from left to right, although this is hardly recognizable to the human eye.

Four horizontal generator elements generate signals, in synchronism, under the timing control of the horizontal trigger generator 54. There is a horizontal sweep generator 60 which is conventional, and generates the typical sawtooth-shaped output which commonly is the signal which is employed to control horizontal scanning. The shape of this output signal is shown in Figure 5A. Referring to that figure, as somewhat schematically represented, the far "Left" position is indicated at the bottom and the far "Right" position at the top. The retrace, during which the signal quickly moves back to the

SUBSTITUTE SHEET 31

start* or left position, for convenience, is shown more abruptly than it actually occurs. The horizontal sweep generator 60 and this form of its output signal are well-known to those familiar with the art.

The comparable situation exists with respect to the vertical scanning elements in that a vertical sweep generator 62* one of three vertical sweep genera¬ tor elements controlled in synchronism by the triggering output signals of the vertical trigger generator 56, is of a conventional type* repetitively generating sawtooth signals, having the known form somewhat schematically shown in Figure 5H. That signal, of course slowly in comparison to the horizontal sawtooth* moves the scanning electron beam downward in conventional television transmitters. Thus* when the horizontal sawtooth is at the point of starting a new horizontal sweep* the vertical has moved the beam to start the sweep at a new vertical position. For interlaced scanning* as herein* this will be to the next odd or even line* depending upon which field is being scanned. The slow period of the vertical sweep signal* as compared to the horizontal sweep signal, is schematically represented in Figures 5A and 5H by indicating that the time scale in Figure 5H is "N" times as great as the time scale in Figure 5A.

∑n the present, higher definition transmitter system 12* a delay horizontal side-step generator 64, an advance horizontal side-step generator 66 and an advance-delay horizontal side-step generator

SUB^STITUTE SHEET 32

68 cyclically provide three different forms of output signals which interact with the horizontal sweep output signal. The output signals of these three elements are represented by the signals shown in Figures 5B, 5F and 5D, respectively. These signals, by comparison with the time scale of Figure 5A, are "stretched out", i.e., the time scale for these signals represents what occurs during a tiny portion of the sweep generator signal. Such is represented by having the time scales for these signals indicated as the time scale for the sweep generator signal divided by "M". Further, the vertical axis for these signals is positioned to indicate that, by way of example, such axis occurs at the time of the point "X" along the sweep generator signal. Thus, the generator output signals shown in Figures 5B, 5F and 5D repeat many, many times over the upward sweep of the horizontal sweep sawtooth. They are triggered at the same time as the triggering of each cycle of the horizontal sweep output in order to be in synchronism with it. In addition, for ease of understanding, and in accordance with the somewhat schematic representa¬ tion herein, it is evident that the vertical aspect of the representation of these signals, as well as the vertical aspect of the representation of the related adder output signals referred to immediately below, is emphasized herein by representing them on a scale much larger than for Figure 5A.

Turning to the adder aspects, there is then a delay adder 70 which has two summing inputs, one to receive the horizontal sweep output and the other to

SUBSTITUTE SHEET -33-

receive the delay horizontal side-step output. As indicated by its name, this adder then sums its two input signals in conventional fashion. Similarly, there is an advance-delay adder 72 to do the same for, again, the horizontal sweep output and the advance delay horizontal side-step output. Finally, there is a third, advance adder 74 which does the same type of summing, to form a sum output signal, from, again, the horizontal sweep output signal and the advance side-step output signal.

The three adder output signals, merely derived by summing operations from the other signals which have already been described, are represented in Figures 5C, 56 and 5E, indicated on the same time scale as for their inputs which are summed with the sweep output signal. As is well evident. Figure 5C represents the output signal for the delay adder 70; Figure 5G represents the output signal for the advance adder 74; and Figure 5E represents the output signal for the advance-delay adder. In each case, the position, with respect to the adder output signal, of the sweep output signal, is indicated by dashed lines. Referring to this, the form of the delay adder output signal has the appearance of a staircase on which the phantom sweep output signal rests; the advance adder output signal has the appearance of a staircase which rests on the phantom sweep output signal; and the form of the advance-delay adder output signal has the appearance of a staircase through which the phantom sweep output signal runs. 34

As indicated, the signals in Figures 5A through 5G are somewhat schematically shown. However, this fashion of representing them clearly indicates their form and relationship, particularly in view of the well-known aspect of the typical horizontal sweep signal, its cyclical nature and the desired, step form for the adder output signals. Thus, the adder signals, of course, will cyclically follow in step with the horizontal sweep output, but providing the different outputs indicated in the figures. This should be readily apparent to those familiar with the art.

Turning to the vertical sweep aspects, a traditional vertical sweep generator 62 and the form of its output signal, shown in Figure 5H, have already been referred to. For purposes of illustration, a portion of the vertical sweep output on a much-expanded time scale is shown in Figure 51. To indicate this, the time scale there is represented as being the time- scale for the vertical sweep divided by "M x N" or, stated another way, the same time scale as for Figures 5B-G. The vertical sweep output portion shown in Figure 51, by way of example, is assumed to be in the vicinity of the point "X" marked on the vertical sweep output in Figure 5H, with this being indicated by the alignment of the vertical axis in Figure 51 with the "X" of Figure 5H. The expanded portion in Figure 51 is shown as horizontal because, for the time scale of the figure, it would have the appearance of being almost horizontal. This, of course, is well understood by those familiar with the art. 35

Now, somewhat analogously to the situation for the horizontal scan elements, the output signal from a down-up vertical step generator 76, in the vicinity of the point "X", is shown in Figure 5J, and the output signal from an up-down vertical step generator 78, in the vicinity of the same point, is represented in Figure 5L. Similarly to the situation for the horizontal scan signal representations, for ease of understanding, it is evident that the vertical aspect of the representations of these signals, along with the adder output signals referred to immediately below, is emphasized by representing them on a scale much larger than for Figure 5H.

Turning now to the adder aspects, an up-down adder 80 adds the vertical sweep output and the up-down vertical step output to provide the sum. signal, repre¬ sented in Figure 5M, as its output. Similarly, a down-up adder 82 has as its inputs, the vertical sweep output and the down-up vertical step output, to provide the signal represented in Figure 5K, as its output signal. As can readily be seen, the up-down vertical step output signal and the down-up vertical step output signal, essentially, are square wave signals which are 180 degrees out of phase with one another. Similarly, the up and down steps provided by these signals, in regard to the adders with which they are respectively associated, result in square-wave type excursions along the two adder output signals which are 180 degrees out of phase with one another.

SUBSTITUTE SHEET 36

The vertical sweep output signal's relation¬ ship to the adder output signals is indicated by the dashed lines, representing the sweep output signal, in Figures 5M and K. As previously indicated, due to the time expansion, the slight off-horizontal slant to the portion of the vertical sweep shown in 51 has not been indicated; and in accordance with this, the same slightly off-horizontal direction would apply to the signals of Figures 5M and K, but is not shown, because of the time scale.

In Figure 3, the horizontal trigger generator output is provided to the two vertical step generators 76 and 78 so that their periodic cycles can readily be maintained in synchronization with the periodic cycles of the side-step generator outputs in the horizontal scanning. This horizontal trigger generator output is also shown as provided to the vertical sweep generator 62 in the event, for some reason, it is desired to modify the sweep generator to be aware of each hori-. zontal synchronizing indication along the horizontal trigger generator output.

The output signal of the vertical trigger generator 56 is provided to the down-up step generator 76 and the up-down step generator 78 so as to also make synchronizing by these generators with the vertical sweep generator available, for example, if it is desired to stop the square-wave variations of the output signals for these generators during retrace of the vertical sweep output signal. One, similarly, might also-incorporate in the various horizontal

SUBSTITUTE SHEET 37

side-step generators the capability to set their outputs to zero during horizontal retrace if, for some reason, such is desired.

As already noted, it is important that the up-down step and down-up step output signals be synch¬ ronized with the horizontal sweep and the various horizontal side-step output signals for the horizontal sweeping. Thus, the start and end of the high and low half-cycles for the square wave signals in the vertical operation match the onset and end of the horizontal portions of the step-shaped signals in the horizontal operation. At the same time, of course, the phase - relationships among the horizontal operation signals, as previously explained and described, exist and are maintained and the phase relationships between the various vertical operation signals, as explained and described, exist and are maintained.

it further might be noted, that, for some reason, it may also conceivably be desirable to have the output signals of the vertical step generators 76 and 78 set to zero during horizontal retrace, and the provision of the horizontal trigger output signal to them, of course, also provides this operational capability.

As previously indicated, for convenience of description and ease of understanding, it has been assumed that the 525 horizontal line, two-field inter¬ lace, scanning context is the context for which the

SUBSTITUTE SHEET 38

particular higher definition television transmitter system embodiment 12 is adapted. Therefore, the standard horizontal sweep generator 60 and vertical sweep generator 62 operation, and the relationship between the output signals of these generators, as represented in Figures 5A and 5H, is such that the vertical sweep output places the electron beams of the scanned image surfaces (in the three-beam color imaging device 28) at the odd-numbered lines for one scanning field, at the even-numbered lines for the next scanning field, at the odd-numbered lines again for the following scanning field, etc.

This is represented in Figure 6B, which represents the movement of a scanning electron beam on four horizontal lines, for a traditional lower defini¬ tion transmitter imaging device (as well as for a traditional lower definition receiver display device). The checkerboard background and divisions shown on the scan surface of the device are present as a visual aid to understanding the present subject matter, by com¬ parison to standard lower definition equipment and operation. Therefore, they do not represent any actual divisions somehow placed on a scan surface. Again, here, the scanning and the pattern placed on the drawing are shown as horizontal although in actuality there is a slight tilting downward, toward the right. For the small area of the scanning which is represented, to the human eye, the scanning and pattern nevertheless would appear almost horizontal.

SUBSTITUTE SHEET 39

An odd line A arrow 82 then represents the path of the center of an electron-scanning beam as it moves along odd line A and an odd line B arrow 84 represents the same thing, but for scanning along odd line B. These odd lines would then, in the traditional format, be scanned as one interlace field; and even line A and even line B would then be scanned as part of a next even line field. Then, on the next pass, the odd lines, including odd line A and odd line B would again be scanned, etc. Even line A arrow 86 and even line B arrow 88, then, represent the movement of the center of the electron beam as it scans these even- numbered lines.

According to the most traditional form of operation, the electron beam scans continuously. Thus, as it moves, its characteristics, as affected by the images on the scanned surface, change to vary in accordance with such images. However, the beam, as it encounters the images, is a continuous beam which varies, and it does not move discontinuously with starts and stops. This is represented in Figure 7B in which the stripe 90 represents the continuously operating electron beam as it scans.

The concept of the degree of horizontal definition for a continuous beam has been treated in the "Background of the Invention" section. In that section, it was indicated that, e.g., for the NTSC luminance signal bandwidth of about 4.2 megaHertz, the number of half cycles along a horizontal line is

SUB_STITUTE SHEET 40

typically considered as the number of divisions along the line useful for measuring the degree of definition. As further indicated there, 440 of these divisions, in the NTSC system, are typically employed as the active portion of a scanned surface. In accor¬ dance with this, the two equal horizontal divisions in Figure 7B are intended to represent two such equal divisions — a left 92 horizontal division and a right 94 horizontal division.

The positions of these divisions are then conveniently represented by the left horizontal division "X" 96 and the right horizontal division "X >f"t 100, as these points are representative of the posi- : tions of the two divisions on .the scanned surface. The points then also conveniently represent two positions indicative of the beam's scanning movement. These divisions, in the context of traditional televi¬ sion scanning, are sometimes referred to as "picture elements" or "pixels".

However, the term "pixel" is perhaps more clearly applicable in the context of a scanning opera¬ tion which is discontinuous, for example, the type of scanning operation which employs, at a receiver end, a digital memory location for each division of a scanned surface indicating an electron beam signal for that division. The beam then moves in discontinuous fashion, e.g., from one center point for a division to a comparable center point for the next division. This

SUBSTITUTE SHEET 41

sort of discontinuous beam movement, also then appli¬ cable at the transmitter end,is schematically indicated by a left-hand circle 102 centered about the left horizontal division "X" 96 and a right-hand circle 104 centered about the right horizontal division "X" 100 in Figure 7B. Although this discontinuous type of opera¬ tion for television systems is not now commonly in use, that sort of operation is commonly in use for computers. However, its implementation for television systems, is and has been readily accomplished.

As previously indicated, however, for pur¬ poses of the present description, the traditional continuous beam scanning is assumed to exist for the lower definition television receiver systems 14 (Figure 1 ) and for the transmitter systems which were designed with their operation in mind. However it should be apparent that the principles of the present subject matter have direct applicability to communication systems having lower definition receivers with dis¬ continuous as well as continuous beam scanning.

The description of Figure 3 already provided, while revealing part of the operation of the scanning and synchronizing circuits 22 of the higher definition transmitter system 12, of course also, by incorpo¬ ration, reveals the design of the scanning and synch¬ ronizing circuits for a traditional lower definition transmitter system. Thus, such a traditional system would most typically incorporate a synchronizing generator, a horizontal trigger generator, a vertical

SUBSTITUTE SHEET 42

trigger generator, a horizontal sweep generator and a vertical sweep generator, without the other elements already described or which remain to be described. The outputs of the traditional transmitter's horizontal sweep generator and vertical sweep generator would then directly be applied as the horizontal deflection and vertical deflection outputs of the scanning and synchronizing circuits, provided to the imaging device.

Now turning to remaining aspects of Figure

3, a cycle sync pulse generator 106 receives the output signal of the vertical trigger generator 56 to provide, after the pulse generator is turned on, an initial pulse and subsequent pulses every sixth field, indicative of the higher definition operation.for the transmitter. It is assumed that the trigger generator signal incorporates the capability to indicate to the pulse generator whether an upcoming field is the first or second field of a traditional two-field scanning sequence. Thus, the pulse generator can be set to initiate its six-field cycled pulses at the onset of the field ending a traditional two-field sequence, to indicate the onset of higher definition operation for the next field. It should be noted that, for example, the output of the vertical sweep generator 62 could alternatively provide the input to the cycle sync pulse generator.

With the onset of the generation of pulses by the cycle sync pulse generator 106, the operation of a cycled three-output selector 108 and of a cycled two-output selector

SU 43

110, is enabled by the generator output, to determine, during the course of higher definition operation, which of the three adder outputs for horizontal scanning provides the horizontal deflection signal to the imaging device at any given time, and which of the two vertical scanning adders provides the vertical deflection signal to the imaging device at any given time.

Thus, the cycle sync pulse generator 106, when its on-off switch 112 is turned on to indicate higher definition operation, generates along its output signal an initial cycling pulse for the field just prior to the beginning of a six-field scanning cycle for higher definition operation. The first two fields are for odd- and even-line scanning under the control of the delay adder 70 and the up-down adder 80. The second two fields are for odd and even line scanning under the control of the output signals of. the advance- delay adder 72 and the down-up adder 82. The final, two fields are for odd and even line scanning under the control of the advance adder 74 and, again, the up-down adder 80. And another cycling pulse is generated for the last of these two final fields to maintain the enabled operation of the output selectors and, thus, the higher definition operation.

The cycle sync pulse generator 106 generates its pulse a set time after the vertical trigger gene- rator 56 provides its triggering signal to trigger the vertical sweep generator 62 and other of the elements in Figure 3. In the present embodiment, the pulse appears 44

during the vertical interval prior to the onset of scanning for the field immediately prior to the field for which the higher definition operation is to begin. Thus, the pulse generator provides a pulse to initially enable the cycled three-output selector 108 and the cycled two-output selector 110. These selectors each then have a counting input to count the number of vertical triggering indications provided along the output signal of the vertical trigger generator 56 beginning after they are enabled. Thus, this counting begins for the vertical triggering of the field after the field of the initial generator pulse.

The cycle three-output selector 108 has three counting output lines, one to the delay adder 70, one to the advance-delay adder 72, and a third to the advance adder 74. These output signals count the tiggering indications from the vertical trigger genera¬ tor 56 in two's. Thus, the output line to ^'the delay adder 70 goes high when a first triggering indication is received, remains high after a second is received, but goes low on receipt of a third, at which point the output line to the advance-delay adder 72 goes high. That output line then remains high for the period after the second and a third triggering indication, at which point it goes low and the output line to the advance adder 74 goes high. The output line to the advance adder then remains high for the period after the fourth and a fifth triggering indication, after which the output line to the delay adder again goes high. As indicated, only one of these output lines is high at a

SUBSTITUTE SHEET 45

time. These output lines then control the three indicated adders, with the output signal on the adder having the high input serving as the horizontal deflec¬ tion output for the scanning circuits while it is high. The output signals of the adders which have low input signals from the cycled three-output selector 108 appear, in effect, as open circuits while their inputs are low ~ i.e., their output signals, in effect, are internally open-circuited.

As is apparent, this process provides for delay adder control for an initial two fields, advance- delay adder control for the successive two fields, and advance adder control for a final two fields of cycled six-field scanning.

When the on-off switch 112 for the cycle sync pulse generator 106 is off, no pulses are re¬ ceived by the cycled three-output selector 108, and its counting output signals all go low, while a fourth locking output signal goes high. This places a hori¬ zontal pass-through circuit 114 into operation which merely passes through the output signal of the hori¬ zontal sweep generator 60, having the traditional form, to control the horizontal deflection output of the scanning circuits in accordance with traditional lower definition operation. Therefore, when the cycle sync pulse generator is turned off, the horizontal scanning for the transmitter is according to the traditional, lower definition format.

SUBSTITUTE SHEET 46

The operation for the vertical scanning is similar. Thus, the cycled two-output selector 110 has a counting input and two counting outputs. It operates analogously to the cycled -three-output selector to provide a high signal at its first counting output for the periods following an initial two triggering indications from the vertical trigger generator 56 which it receives after it is enabled by an initial enabling pulse from the cycle sync pulse generator 106. Then a high signal at the selector's second counting output obtains during the periods following a third and a fourth pulse, after which the first counting input again goes high, etc. The up-down adder 80, in a fashion similar to the situation for the horizontal scanning, then controls the vertical deflection output during the first two periods and the down-up adder 82 controls the vertical deflection output during the latter two periods. If cycle sync pulses are not received, then the locking output of the cycled two- output selector goes high, the counting outputs remain low, and a vertical pass-through circuit, in effect, passes through the output of the traditional vertical sweep generator 62 to provide a traditional, lower definition vertical scanning signal.

Turning to Figures 6A and 7A, the three different scanning position configurations provided during higher definition operation, as somewhat schema¬ tically represented, can readily be seen. Thus, during the first two fields, when the delay adder 70 and the up-down adder 80 are in control, the electron beam jumps, from left to right, to positions represented by

SUBSTITUTE SHS=ET 47

the dots labelled "1". It does this for the odd line A and the odd line B in one field and for the even line A and the even line B in a second field.

For the next two fields, when the advance- delay adder 72 and the down-up adder 76 are in control, the electron beam scanning is according to the positions represented by the dots labelled "2", for odd line A and odd line B in one field, and for even line A and even line B in another field.

Finally, for the final two fields of the six-field cycle, the scanning beam jumps according to the positions represented by the dots designated "3", again for odd line A and odd line B in one field, and for even line A and even line B in another field. Then, the cycle begins again.

In Figure 7A, which is analogous to Figure 7B discussed earlier, but for the higher definition scanning, the situation is shown in more detail with higher definition circles 116 representing an electron beam at the various positions. As indicated by com¬ parison with 7B, the beam, of course, is typically a more focused beam for the higher definition operation. Thus the imaging device might well be provided with the capability for a beam adjustment action through a connection to the on-off switch 112, rather than, for example, relying on a manual adjustment.

The signals shown in Figure 5, as imple¬ mented, will move the electron beam quickly between positions and then maintain the beam for a relatively

SUB 48

long time at the positions. Thus, the beam actually, essentially, follows a zigzag path as it moves along a line. The quick jumps between positions will make the electron beam virtually ineffective as a scanning tool during the jumps, a situation which is seen as desirable in the higher definition context.

In referring to Figures 6B, 7B and 6A and 7A, it will be seen that the scanning for the higher definition operation provides three different scanning position variations of the traditional scanning position arrangement. At the same time, it provides, during the course of its three-variaton scanning, identi¬ fied groups of three scanning positions along sideways- extending (horizontal) lines. These groups form triangular-shaped configurations, and, as can be seen, alternate the orientations for the triangular bases. By way of example, the first two configurations in Figure 6A are representative, the first one 120 having its base upwardly oriented and the second one 122 having its base downwardly oriented. These triangular, non-orthogonal arrangements are considered to be of substantial significance. They provide for relatively "close-packing" in the same fashion that a hexagonal arrangement of atoms in a crystal can provide denser packing than a cubic arrangement. In effect, the indicated variations enable a beam size such that more total area can be covered by the electron beam for the indicated scanning positions of the beam.

A cycle sync insertion pulse generator 124 is connected to the output line of the cycle sync pulse

SUBSTITUTE SHEET 49

generator 106. Upon receipt of a pulse, it also provides a pulse along its output signal. That pulse, provided to the composite video formation, control and amplifier circuits 32, operates to cause insertion of a pulse along the signal which is provided to the video transmitter antenna 34. In the transmitted video signals, this pulse becomes a marker indicating the field immediately prior to the field of onset of higher definition operation. At the receiver end, as will later become evident, this provides the receiver system with one field advance "warning" to begin its higher definition operation.

It will be apparent that the insertion of a pulse along the signal provided by the composite video formation, control and amplifier circuits 32 to the antenna 34 may be readily accomplished by a conven¬ tionally implemented, simple modification of tradi¬ tional circuits of that type. For example,- the tradi- tional circuits can be divided into "front-end" and

"back-end" portions, and a conventional summing element can be connected therebetween. The summing element then will receive the traditional signal at that point in such composite circuits 32, as one of two summing inputs, and the signal from the cycle sync insertion pulse generator as the other input. This will result in the desired pulse insertion in the sum signal which is then sent by the summing element to the front-end portion of such composite circuits.

Now referring to Figure 9, there is shown somewhat schematically, a representation indicative of transmitted video signals generally in accordance with the TTSC Standard, and, specifically, of amplitude

SUBSTITUTE SHEET 50

variation for transmitted video imaging signals. For convenience of description and ease of understanding, the axis at the left is marked "darkest" and "lightest" as if the signal were simply the luminance signal indicative of the degree of lightness or darkness. Miscellaneous timing signals, such as equalization pulses, are not shown for the same reason. In addi¬ tion, the form of variations caused by the chrominance (color) signal when combined with the dominant lumi- nance signal has similarly been omitted. However, as previously indicated, the chrominance signal is pro¬ vided in combination with the luminance signal in the framework originally adopted for only a luminance signal — i.e., black and white operation — so that the essential black and white format for amplitude variation for the video imaging signals was preserved even with the inclusion of color. The matters omitted in the simplification, as will be evident to those familiar with the art, have no bearing on the pertinent transmitted signal matters herein.

Along the initial portion of the video imaging signals indicated in Figure 9, there are indicated to be video imaging signals for three horizontal line scans. Thus, there are three color burst occurrences 126 used in the color operation of the receiver system. As is well known to those familiar with the art, these color bursts are short bursts of the frequency of the color subcarrier signal which are employed in synchronizing operation of the color signal treatment circuits 44 in the receiver system with color operation in the transmitter system. This, of course, is all standard. Also, there are indicated three 51

horizontal synchronizing markers 128 to synchronize the horizontal line scans of the receiver system with those of the transmitter system. Then, there are also indicated the three sets of variations 130 which provide the video information for establishing the images in the receiver system.

Following the initial portion, there is indicated a vertical interval for the period after completion of one field, at the bottom, prior to onset of scanning for the next field at the top. Thus, the initial portion in Figure 9 represents the last three lines of a field before the vertical interval. As indicated, the horizontal synchronizing markers con- tinue during the vertical interval, although generally negative-extending rather than positive extending. More generally, it will of course be recognized that the signals generally shown in Figure 9 are in accor¬ dance with the negative modulation format which is standard in the United States, lower levels indicating "lightness" and higher levels indicating "darkness".

After this vertical interval which is shown, it is assumed that the field occurs in connection with which the cycle sync pulse inserter 124 acts to insert a marker indicative of the upcoming first field of a cycle of six high-definition fields. As previously explained, this field for insertion is the last field of the prior cycle (assuming high definition operation has been ongoing). This cycle sync marker 133 is shown in Figure 9 occurring during a portion of the vertical

SUBSTITUTE SHEET 52

interval (prior to the onset of such marker pulse field) for which various test information is typically provided. In accordance with the somewhat schematic nature of Figure 9, this portion is represented as having generally the same signal format as for display scanning, but including the marker pulse 133. Of course, other parts of the vertical interval repre¬ sented uniformly in Figure 9 may also vary from the typical vertical interval format where they are used to transmit other peripheral information.

After the signals for this marker field at 135, there is another vertical interval at 140 and then the first field of the start of the new six-field cycle at 142, followed by another vertical interval at 144 and by the second field of the new six-field cycle, etc.

Referring back to the cycle sync marker 133, this marker can conveniently be provided, and is shown as provided, during the vertical interval, after a color burst, prior to the onset of the first line to be displayed for a new field. In fact, the portion of the vertical interval which is typically used to communicate a VIR signal (a vertical interval reference signal) , which is used by certain forms of receivers, is extremely convenient for locating a marker pulse. This signal occurs along an off-screen horizontal line. It is used by many receivers to automatically control image variables such as color saturation, brightness and black level. It, speci¬ fically, is line 19 in the vertical interval. In the 53

present embodiment, and as shown, the cycle sync marker, thus, is assumed to be transmitted with the VIR signal along the same off-screen horizontal line. For continued higher definition operation there, of course, will be subsequent marker pulses in the same position, for every sixth vertical interval.

In sum, what has been indicated is that an extremely minor change is all that is required in the traditional NTSC signal format to take account of transmission in accordance with the higher definition operation herein. Although a particular place for the cycle sync marker has been indicated, it will be evident to those familiar with the art that other places for the signal, other than along the line for the VIR signal, are readily available and could be alternatively employed.

The scanning in the higher definit «ion tele- vision receiver system of Figure 2, of course, corre¬ sponds to the scanning which has been explained in detail for the higher definition transmitter system 12. Thus, the operation of the various elements of the upper port-ion of Figure 4, to which the signals of Figures 5A through 5M apply in a fashion analogous to their applicability to the transmitter, is rather readily apparent. Further, the applicability of Figures 6A, 6B, 7A and 7B, to scanning for the display^* device of the receiver is, as would be expected, analogous to the applicability of these figures, as already explained in detail, to the scanning in the higher definition transmitter.

SUBSTITUTE SHEET 54

In accordance with this, the following elements in the higher definition receiver system operate and interact in a fashion analogous to the elements respectively comparably named in the trans- itter system: a horizontal sweep generator 148; a delay horizontal side-step generator 150; an advance delay horizontal side-step generator 151; an advance horizontal side-step generator 152; a delay adder 154; an advance delay adder 155; an advance adder 156; a horizontal pass-through circuit 160; a vertical sweep generator 162; an up-down vertical step generator 164; a down-up vertical step generator 166; an up-down adder 168; a down-up adder 170; a vertical pass-through circuit 172; a cycled three-output selector 174 and a cycled two-output selector 176.

Thus, in a fashion analogous to what was explained for the transmitter: Figure 5A is applicable to the output signal for -the horizontal sweep generator 148; Figure 5H is applicable to the output signal for the vertical sweep generator 162; Figure 5B is appli¬ cable to the output signal for the delay horizontal side-step generator 150; Figure 5C is appliable to the output signal for the delay adder 164; Figure 5F is applicable to the output signal for the advance horizontal side-step generator 152; Figure 5G is applicable to the output signal for the advance adder 156; Figure 5D is applicable to the output signal for the advance-delay horizontal side-step generator 151; Figure 5E is applicable to the output signal for the advance-delay adder 155; Figure 5L is applicable to

SUBSTITUTE SHEET 55

the output signal for up-down vertical step generator 164; Figure 5M is applicable to the output signal for the up-down adder 168; Figure 5J is applicable to the output signal for the down-up vertical step generator 166; and Figure 5K is applicable to the output signal for the down-up adder 170.

Similarly, Figures 6A and 7A are fully applicable to the scanning, for the display device, in the higher definition receiver, in a fashion analogous to their applicability to the scanning in the high definition transmitter as explained in detail above. In addition. Figures 6B and 7B, in a fashion analogous to their use n comparing scanning in a low definition transmitter versus the high definition transmitter, are fully applicable to comparing scanning in a conventional low definition receiver, such as the lower definition receivers of Figure 1, by way of comparison to the higher definition receiver.

In light of the analogy of the situation at the higher definition receiver system to that at the transmitter system, additional explanation of only a limited number of aspects of the upper portion of Figure 4, in connection with some related aspects of other figures, is required. Specifically, in the receiver system, there is a conventional horizontal/ vertical sync signal splitter, the vertical trigger output of which serves as the counting input for the cycled three-output selector 174 and the cycled two- output selector 176. This splitter receives its input signal from conventional scan synchronizing signal and color signal 56

separator circuits 182 forming part of the receiver's composite video amplifier, detector and separation circuits 42. The other part of such circuits, as indicated in Figure 4, forms the composite video amplifier and detector circuits, which are also conventional. Thus, the indicated parts of the compo¬ site amplifier, detector and separation circuits and, thus, those circuits as a whole, are essentially the same as for a traditional lower definition receiver, as is also the case with the horiziontal/vertical sync signal splitter 180.

The separator circuits 182 receive the electrical signal representative of the transmitted video imaging signals, after receipt and processing by the composite video amplifier and detector circuits 184. The separator circuits, in conventional fashion, separate out the signal carrying the color information for trans ittal to the conventional color treatment circuits 44 (Figure 2) and for processing by the color treatment circuits in the same fashion as for conven¬ tional lower definition receivers. The separator circuits also separate out the luminance electrical signal for further processing by the luminance signal treatment circuits 26. From that point, the luminance signal is processed in accordance with the operation of the portion of Figure 4 at the bottom of the figure which will be addressed shortly. Of relevance to the scanning circuits 24, the separator circuits also separate out a signal carrying the horizontal and vertical synchronizing information which is carried from the transmitter system by the horizontal

SUBSTITUTE SHEET 57

synchronizing markers, e.g. at 128 (Figure 9), and by vertical synchronizing markers which are incorporated within the signal form for the vertical intervals, e.g. at 132 and subsequent vertical intervals in Figure 9.

Then, in synchronism with the horizontal and vertical synchronizing information received at its input from the separator circuits 182, as carried originally from the transmitter, the horizontal/ vertical sync signal splitter 180 provides a horizontal trigger output to control the timing of various of the horizontal scanning elements and a vertical trigger output to control the timing of various of the vertical scanning elements. Thus, the timing of those hori¬ zontal and vertical scanning elements, vis-a-vis the video information carried to the luminance signal treatment circuits 26 and to the color signal treatment circuits 44 (Figure 1), will be in synchronism with the original generation of the information in those signals vis-a-vis the scanning in the transmitter. The vertical trigger output then is employed to provide the counting input to the cycled three-output selector 174 and to the cycled two-output selector 176.

A cycle sync pulse detector 86, receives the signal which is also transmitted to the luminance signal treatment circuits. The cycle sync pulse detector, looks for a cycle sync scanning marker along this input signal to it, during vertical intervals, with the timing help of the output signal of the vertical sweep generator 162 in determining the

SUBSTITUTE SHEET 58

appropriate specific time in which the cycle sync pulse may be expected. The pulse, of course, precedes the onset of the last field prior to the first field of a six-field scanning cycle. Thus, where high definition transmission is occurring, the cycle sync pulse de¬ tector will receive marker information indicative that the field immediately after the next field will be the first field of a six-field cycle. Based on this, the cycle sync pulse detector 86 generates a pulse along its output signal to the cycled three-output selector 174 and to the cycled two-output selector 176, indicating, for initiation of high definition opera¬ tion, that they should begin their cycled counting starting with the next counting input indication along the vertical trigger signal. Then, so long as suc¬ cessive input pulses are received from the cycle sync pulse detector 86 every six fields, the counting continues and the cycling of the horizontal and verti¬ cal scanning, in a fashion analogous to high definition operation at the transmitter, occurs. However, when such pulses stop, the locking output signals of the selectors go high, disabling the outputs of the three adders for the horizontal scanning and the two adders for the vertical scanning, and enabling the horizontal pass-through circuit 160 and the vertical pass-through circuit 172 so that they control the horizontal deflection and vertical deflection signals provided to the display device.

Another point deserves some mention in connection with the analogy between the higher defini¬ tion display device scanning position variations and

SUBSTITUTE SHEET 59

the higher definition imaging device scanning position variations as both are revealed in Figures 6A and 7A, byway of comparison with traditional low definition transmitter and receiver operation, as both are revealed in Figures 6B and 7B. Specifically, the scanning position variations of Figures 6A and 6B fully apply to higher display device scanning and traditional display device scanning, respectively. However, by way of example and as previously referred to, for the most traditional sort of color display device, the scanned surface of the device is rather densely packed with sets of, in the nature of phosphor "dots" — i.e., sets of green, blue and red dots arranged in a densely- packed pattern over the surface. Then there is a "shadow mask" between the source of the electron beams for the three colors, which contains openings for the^' different sets of phosphor dots. The angular relation¬ ships between the electron beams then assure that the proper beam hits the proper dot. Thus, for^' this sort of arrangement, at the display device, the electron beams encounter the shadow mask and pass through the openings in the mask before actually impinging upon the scanned surface.

By way of example, focusing on the position., carrying a "1" designation at the far left of Figure 6A, in the case of a shadow mask type display, and at the same time focusing on the red electron beam which is then represented by the circle 116, that beam will pass through a number of holes in the shadow mask which the beam encounters and then excite the red phosphors

SUBSTITUTE SHEET -60-

corresponding to the sets of phosphors for those holes. Thus, when that beam is at the indicated scanning position, the electrons of the beam must pass through shadow mask openings before actually encountering the scanned surface. Similarly, the blue or green beam, which is then represented by the circle 116, will pass through the same holes and respectively excite the blue or green phosphors corresponding to the sets of phosphors for such holes. This, of course, is well known and understood by those familiar with the art.

As has been also previously adverted to, other forms of color displays commonly in use have sets of verticel red, green and blue phosphor stripes running down the sanned surface, with in the nature of a shadow mask having vertiσle slits. In that case, the electron beams, at, for example, the position just discussed, must pass through a number of slit openings rather than a number of generally round holes before encountering the display surface at such position.

Of course, a quite different conventional fom of display device, a projection device, provides scanning of three separate surfaces for the three color beams, the employment of a color filter beyond each surface and then the merging of the red, blue and green light beyond the filters onto a screen. This sort of display device is totally devoid of any "shadow mask" structure.

Turning to the bottom portion of Figure 4(2), first of all, it is evidence from what has already been

SUBSTITUTE SHEET 61

explained, that the higher definition process provides a trade-off between spatial definition and time defini¬ tion. Thus, it requires the time for six fields, i.e., for three sets of two interlaced fields, to complete the full high definition cycle for a picture frame. In this time, the three different scanning position variations are scanned. However, in this connection, it should be remembered that each of the six fields does extend over the full display surface. In addition, the scanning positions in each group of three, having a position from each variation, are relatively close to one another. Further, the jumping effect of the high definition scanning is adapted to act on the human eye in a way which tends to provide favorable percep- tion of what appears under the scanning process.

Thus, the trade-off toward higher spatial definition and lower time definition is an eminently satisfactory one for areas of the display which are not changing rapidly. However, in areas of the display where rapid changes are occurring in time, a blurring effect which is disadvantageous will occur. The blurring, as indicated, will be due to the picture frame rate of about ten frames per second rather than about thirty frames per second.

In view of this, in connection with the higher definition operation, it is desirable to also incorporate a capability for shifting back to the traditional higher time definition and lower spatial definition^', for areas of a display where there is rather rapid change. By way of example, for a

SUBSTITUTE SHEET 62

stationary background and an actor moving through the background, the higher spatial definition for the background is advantageous. However, near the edges of the actor, where changes are occurring relatively quickly, the higher time definition can be advantageous. It should be emphasized, however, that the higher spatial definition operation can nevertheless be provided without such shifting back capability.

n this connection, the bottom portion of

Figure 4 undertakes computerized comparisons of degrees of change between prior luminance values for scanning positions and update luminance values for such posi¬ tions. If such a change exceeds defined limitations, the apparatus, rather than waiting for update signals - for the other scanning positions in a triangular group, immediately sets those other positions to the update value for the position recently tested. This, of course, calls for the storage of luminance values for scanning positions in a display memory for purposes of displaying images, and the capability to write changes in the luminance values for positions into the memory - independently of the reading out of the positions for displaying. This is readily understood by reference to the computerized apparatus at the bottom of Figure 4 and to Figure 8 which is a flow diagram for the programmed operation of the apparatus.

In Figure 4, the front-end luminance treat- ment circuits are conventional. Thus, as in tradi¬ tional lowe.r definition receivers, the incoming signal.

SUBSTITUTE SHEET 63

for determining the degree of brightness, at this point, undergoes standard processing before being provided to the display device. The front-end luminance treatment circuits 190 fulfill these normal operations and, in a typical lower definition receiver, from this point, the signal carrying the luminance information would go directly to the display device. In Figure 4, the signal has the capability to do this in certain circumstances through a display pass-through circuit 192 which, essentially, merely passes the luminance signal through from the front-end luminance signal treatment circuits. This occurs under the control of a control and timing unit. 194 when that unit, due to the absence of pulses along its input signal from the cycle sync pulse detector 86, deter¬ mines that the receiver, in fact, is not receiving a high definition signal, is scanning in the traditional manner and, therefore, that the luminance signal should be treated in the traditional manner.

The control and timing unit 194 is imple¬ mented in conventional fashion which is now common¬ place in computerized operations. Thus, it is adapted to receive incoming signals indicative of what is occurring at various points and to, under the control of its program, act to control and time apparatus to carry out the operations explained herein. It is implemented, in conventional fashion, employing a microprocessor, a clocking timing unit, a memory capability including storage of its program and other storage capability for its operation, and other

SUBSTITUTE SHEET 64

elements which are traditionally employed with these elements in providing traditional computerized control and timing functions such as occur herein. The vertical trigger output of the horizontal/vertical sync splitter 180, as well as the output of the cycle sync pulse detector 86, is connected to the control and timing unit from the upper portion of Figure 4, to establish and maintain its timing synchronism with the scanning circuits 24.

For operation as a higher definition receiver, i.e., for operation while receiving transmitted signals for higher definition operation, a display memory 196 typically contains digital video imaging signals representative of luminance values for all of the scanning positions — i.e., the scanning positions in each of the three scanning position variations indi¬ cated in Figure 6A. These video imaging signals can conveniently be 8-bit values. Then, under the control of the control and timing unit 194, acting,in conven¬ tional fashion, on a read address register 200, the digital video imaging signals for the luminance values, in synchronism with the timing of the scanning circuits 24, are read out to a digital-to-analog converter 202, which converts these digital signals back to a continuous analog luminance signal for the display device. For the interlaced scanning format which has been assumed, the scanning positions, of course, will be read out of the display memory in the order for such interlaced scanning. An output filter 204 is present, as is conventional with digital-to-analog converters, to eliminate harmonics and related undesired effects.

SUBSTITUTE SHEET 65

The filter might typically filter out frequencies greater than the frequency corresponding to one-half the rate of positions read and converted to analog.

At the input side, there is a comparable input filter 206, standard in the case of analog-to- digital conversion, which might typically cut off frequencies greater than one-half the sampling and conversion rate by an analog-to-digital converter 208. This converter receives the incoming signal repre¬ sentative of luminance values for scanning positions and converts it to digital video imaging signals, e.g., having eight bits. Assuming the apparatus is in the course of normal high definition operation, and the converter has just made a conversion to digital for a particular scanning position, there will be a prior set of digital luminance value, video imaging signals in the display memory for that position. Assuming that position has not undergone a shift to lower¹ spatial definition and higher time definition since its last update, the same set of video imaging signals will be present in the appropriate location of a pre-display memory 210. This pre-display memory has an address register 212 for setting the memory location which is to be read from or written into at any given time.

For each scanning position location which has not undergone a shift to lower spatial definition and higher time definition after the time of its last update, the pre-display memory digital signals for the luminance value will be the same as for the display

SUBSTITUTE SHEET 66

memory 196. However, where that position has under¬ gone such a shift, it has done so because of a signifi¬ cant change in the luminance value of another one of the scanning positions in its group of three tri¬ angularly arranged positions (Figure 6A)• Thus, to shift to the higher time definition, the luminance value for that position has been set in the display memory 196, under the control of the control and timing unit 194, to the same, significantly changed luminance value for the associated scanning position in its group. As should be apparent, this creates the lower spatial definition by setting the luminance values for displays of the group of three positions to the same value. It increases the time definition, by updating the associated positions of the position which has undergone significant change sooner than they would otherwise be updated — i.e., at the time when the associated position changed rather than later in the six-field cycle. It also creates differences in the luminance values in the display and pre-display memories for each of the associated positions. Thus, where such an associated position has been changed, the pre-display memory luminance value for that position remains at the prior value for that position and is not changed to the updated value for the associated position, That is the reason why the values for the same position in the two memories are the same only if there has not been a shift to high time definition for the position since its last update.

Mow returning to the incoming digital signals representative of the luminance value for a specific

SUBSTITUTE SHEET 67

scan position, that value is provided to a comparator 213 where, under the control of the control and timing unit 194, that value is compared with the prior value for that scan position in the pre-display memory. If the change exceeds a defined degree or amount of change, this calls for a shift to higher time defini¬ tion and lower spatial definition for the triangular group of positions of which the tested position is a member. Thus, under the control of the control and timing unit: the display memory locations for the two associated scan positions are addressed through a write register 214 and the incoming luminance value is read into those positions? the location for the scan posi¬ tion under direct test is also addressed through such register and the new luminance value is read into that position; and, in addition, the new luminance value is read into the pre-display memory only at the location for the scan position under direct test, not in the locations for the associated positions. Thus, the true, prior values for the associated positions will be employed for comparison purposes as they undergo direct testing subsequently in the six-field cycle process. If one of them, at that point, under¬ goes a significant change, then the scanning position luminance values in the display memory for the two associated positions (including the one that was just under direct test) will be changed to the value for the position being tested.

It will be evident that the apparatus at the bottom of Figure 4 undertakes its computerized activity in a time frame which is compatible with the timing of

SUBSTITUTE SHEET 68

the scanning circuits 24. Thus, the comparison and update process, as just explained, occurs on a rela¬ tively faster time scale than the scanning time scale, to maintain essential synchronism. In this connection, since the display memory location which is necessarily being updated is the position concurrently involved in the scanning process, in the embodiment shown in Figure 4, it is important that the timing of the reading out from the display memory, for that position, be after the update value has been read into that position using the address in the write register during the relatively fast computerized process. Such timing rates and timing operation for computerized functions are readily incorporated in accordance with conven- tional, present-day computer capabilities.

On the other hand, it will be readily apparent that conventionally implementing a delay capability in the horizontal deflection and vertical deflection signals could readily be implemented to address any timing delay considerations which may be raised in various alternative implementations. Additionally, of course, the operation for the lower portion of the figure could be implemented so that the reading-out of luminance values from the display memory is independent of the timing of the incoming luminance signal. Thus, the display memory could be operated, apart from the updating and comparison involved in providing the values in its storage locations, as a conventional memory buffer having read-out timing essentially uncoupled from timing of the incoming luminance signal. Thus, the display memory locations could be read out in a fashion uncoupled from when they are read in and the timing of the scanning circuits could be modified to

SUBSTITUTE SHEET 69

correspond to the read-out procedure for the display memory. In accordance with this, the read-out proce¬ dure could well not adopt the reading out of interlaced fields based on odd- and even-numbered lines and substi- tute a progressive reading based on the true line order. Also, the reading-out and display aspect could involve a faster rate. In either case, one, of course, would expect the modification to involve the incorpo¬ ration, to some degree, of the refreshing of the display with repeat luminance values for positions. If this sort of conventionally implemented adaptation were done, a corresopnding buffering and read-out operation, of course, could be implemented in the color signal treatment circuits 44 (Figure 2).

It might also be noted that the operation calling for shifts between higher spatial definition with lower time definition and higher time definition with lower spatial definition, for various parts of the display, will cause a substantial or total change to high time definition for a period after an abrupt scene change. However, this is not a significant drawback since it takes the human eye about one-half second to perceive new fine detail on a display after an abrupt change.

Figure 8 shows in concise, flow diagram form the programmed operation of the apparatus in Figure 4 for shifting between higher spatial definition and higher time definition, for various areas of the display, which has already been described in some

SUBSTITUTE SHEET 70

detail. Thus, the analog-to-digital converter 208 converts the analog signal applicable to update of an identified scan position to a digital format at 215 of Figure 8. Then a comparison of the digital value for the update of the position with the prior value stored in the pre-display memory 210 is carried out at 216. This is done by the comparator 213 and a determination is made as to whether the update and pre-display memory stored values significantly differ, at 220. If they do not, the stored value for the position in the display memory 196 is changed to the update value at 222, the value previously stored in the pre-display memory for the position is similarly changed to the update value at 224, the next scan position for update is identi- fied at 226, and the process again begins for the next position.

If, however, a significant difference is determined to exist between the update value and the . value stored in the pre-display memory, several other steps occur before the updating of the display memory stored value at 222. The first step is the identi¬ fication of the two positions which are grouped, according to the triangular configuration, with the position under test, at 228 of Figure 8. After such identification, the display memory stored digital values for these two associated positions are updated to the update value for the position of the group directly under consideration. This occurs at 230 of the flow chart.

SUBSTITUTE SHEET 71

It will be apparent that some of the details of the flow chart of Figure 8 can straight¬ forwardly be altered. For example, it may well be desirable to update the display memory stored value for the position under test immediately after the comparison occurs even where the comparison indicates a significant change and that the two associated positions must be dealt with. This would achieve the change of the display memory for the position of concurrent scanning concern relatively sooner even where the associated positions must be changed. In fact, the update value for the position under test could be provided to the display memory prior to the carrying out of the com¬ parison which is required, as that update occurs independently of the outcome of the comparison.

With regard to the comparison of update digital video imaging signals for a scan position with the prior signals for the position, and determining whether the degree of change is "significant", some additional comment is appropriate. By way of example, the difference in value defined as a "significant" change could be set in the receiver system at the time of manufacture or calibration of the system. It could, alternatively, be adjusted in the apparatus itself, depending on what is occurring at the particular time. Thus, it could be a variable value which changes over time.

A modification could also readily be adopted involving a defined range of change less than that

SUBSTITUTE SHEET 72

deemed "significant" enough to change the display memory values for associated positions in a group to an updated value for the position of the group under direct test. However, the degrees of change in this range could be deemed meaningful enough to call for some modification for the associated positions, but to an "in-between" value. By way of example, the stored value in the display memory for the position under test might be represented by the number "M", with an update value represented by the number "N", and with the difference between M and N not being sufficient to set the stored luminance values for the associated positions to N. However, if this difference is in the meaningful range, then, by way of example, the average of M and N might be calculated and the display memory luminance values for the associated positions might be set to that average — i.e., (M + N)/2.

Now referring back to Figures 6A and 6B, related Figures 7A and 7B, and the timing indicated in Figure 5, it is readily apparent how a con¬ ventional, lower definition television receiver system, such as the lower definition systems 20 of Figure 1, will merge the luminance levels for the successive scanning position variations of a higher definition receiver system as described herein. Thus,

SUBSTITUTE SHEET 73

while the successive luminance levels for the "1" "2" and "3" scan positions in Figures 6A and 7A will be separated in the scanning process for the higher definition receiver, they will successively fall on the same scanning position in Figures 6B and 7B for the lower definition receiver. Since the three positions are close together, the merging will nevertheless provide effective, readily acceptable operation of the lower definition receiver from the transmitted signals from the high definition transmitter. This capability for merging, or repetitive spatial definition of the same scanning positions for a lower definition receiver from the transmitted video signals for different scanning positions of the.higher definition receiver, is considered to be of substantial significance. Of course, as is apparent from Figures 6 and 7, the electron beam size for the higher definition receiver, during its higher definition scanning, will typically be smaller than that for the lower definition receiver. In this connection, one may well wish to implement an automatic beam focus adjust dependent upon whether the cycle pulse detector 86 of the higher definition receiver is providing pulses indicative of higher definition scanning, rather than relying on a manual adjust capability.

Along somewhat similar lines, it should be noted that according to a common form of traditional receiver operation, which has been assumed in the description herein, the luminance signal "Y" is pro¬ vided to the-display device 46 (Figure 1), and the

SUBSTITUTE SHEET 74

color signals are provided to such device having the luminance signal "Y" subtracted from them (Figure 1). However, the operation of the higher spatial definition versus higher time definition shift apparatus in the lower portion of Figure 4 alters the luminance signal "Y" separately provided to the display device because of the changes made in associated scan positions to equal an update value of a scan position under test. With regard to this, in employing the "Y", "R-Y", "G-Y" and "B-Y" signals, a display device will typically employ a form of combination of the four inputs resulting in the three red, green and blue signals for the red, blue and green guns of the display device. However, because of the manipulation of the "Y" signal in the bottom portion of Figure 4, this combining will not always be accurate.

Concerning this, as previously noted, the color capability under the NTSC Standard is incorpo- rated in a fashion so that the color information fits within a channel initially provided with only a luminance signal in mind. In addition, the sensitivity of the human visual system to luminance, and changes therein, is substantially greater than for color. These factors, and other inherent limitations in what is accepted in present-day television, make the indicated deviation from the ideal — this "artifiact" caused by the spatial versus time definition shifting herein — readily acceptable, and this is not considered to be a significant disadvantage. Similarly, the same general considerations are at work in the great advantage which can be derived from the capability 75

for the spatial versus time definition shifting for the pure luminance signal without concern for this in regard to the signals carrying color information. Of course, in accordance with modifications, one could adopt the shifting capability for the color signals also. However, the substantially more coarse, less sensitive information which is provided over an NTSC channel for color, and the lesser sensitivity of the human eye to color than to brightness, substantially detracts from and minimizes the value which might theoretically attach to this.

A few additional points might be finally noted.

First, the cycle marker 133, as it occurs along the transmitted signals in Figure 9, is not beyond the "darkest" level which is traditionally the case for horizontal synchronizing markers and vertical synchronizing markers (as shown). This is specifically provided so that the scan synchronizing signal separator and splitter circuitry (Figure 4 at 180 and 182), which is adapted to look for horizontal and vertical synchronizing signals beyond the "darkest" level, will not be confused by the cycle marker. Second, the choice, for the position of the cycle marker, of the vertical interval prior to the field preceding the field of the onset, or the first field of the continua¬ tion, of higher definition operation, is merely one of a number of choices. By way of example, in accordance with straightforward modifications of the components and operation at the transmitter and receiver ends, the 76

vertical interval of the next field could be used or even a position after such vertical interval but prior to the onset of image scanning for such next field.

Continuing with such additional points, and thirdly, it could be desirable to employ phosphors having longer decay times in the higher definition receivers than those that are most commonly in use in receivers today because of the trade off between spatial and time definition. Fourth, it may well be most desirable to employ conventionally implemented large front or rear projection displays in higher definition receivers, as large size capabilities, most readily available in projection receivers, are one reason for desiring higher definition. Fifth, it perhaps bears re-emphasis that the merging on one scan position, in a lower definition receiver, of what otherwise occurs for three related scan positions in a higher definition receiver takes place because the single position is repetitively defined, three times, in the course of defining, separately, each of the three positions of the higher definition receiver. Sixth, recent studies and experience reveal that aspect ratios of in the range of 5:3 rather than, for example, 4:3 may be desirable. If it is desired to implement this in the higher definition receivers, then the lower definition receivers may simply have small portions at the top and bottom of their screens blocked off. Seventh, it is apparent in Figures 6 and 7 that the scanning position variations for the higher definition receivers employ left and right sideways excursions and upward and downward excursions in establishing their varia¬ tions over the scanning position arrangement for the lower definition receivers. 77

Further, it will be evident that the prin¬ ciples applied to the specific embodiment herein could readily be implemented in an embodiment preserving the same sawtooth shape for the horizontal scanning control, but delaying its onset for a first field position variation (such as the "1" positions here), advancing its onset for a second scan position variation (such as the positions "3" here) and maintaining its normal onset for a third scanning position variation (the positions "2" here). In accordance with this, the horizontal operation would be much more similar to the continuous sort of horizontal operation which is most traditional. However, it is emphasized that the more discontinuous horizontal operation is considered advantageous.

Also, it should be recognized that, although solid-state charge coupled imaging devices may well become commonplace in future transmitter systems, the principles herein are fully applicable to such devices. Those devices, of course, generate charge levels that relate to light levels for the images on the devices; and such charge levels can then be straightforwardly measured, without the need for any electron beam involvement, as electrical signals, in accordance with position. Such measurements can also be stored in a device memory, and read out of the memory, in accor¬ dance with position. Thus, in accordance with the principles herein, the scanning, for that form of imaging device, involves the measurement of the charge levels provided by such form of imaging device as images are established for the device.

SUBSTITUTE SHEET 78

Finally, it is again emphasized that the principles herein are generally applicable to televi¬ sion communication systems other than those following the NTSC Standard where the same problem of incorpo¬ rating higher definition operation also exists. For example, the principles herein are readily applicable to countries following the PAL (Phase Alternating Line) Standard and countries following the SECAM (System Bn Colours A Memoire) Standard.

In accordance with the foregoing, it will be readily apparent that many changes and modifications may be made in the particular embodiment which has been described in detail herein without departing from the scope or spirit of the invention.

SUBSTITUTE SHEET

Claims

79

WHAT IS CLAIMED IS: 1. A television transmitter system for concurrently generating and transmitting video signals for a relatively higher spatial definition television receiver system and a relatively lower spatial defini- tion television receiver system, comprising: imaging means to establish images for transmission to the receiver systems; means for scanning, for said imaging means, a plurality of different scanning position variations of a scanning position arrangement for the relatively lower definition receiver system, said different scanning position variations substantially corresponding to scanning position arrangements for the relatively- higher definition receiver system; and means for generating and transmitting video imaging signals for said plurality of different scanning position variations to cyclically define the sub- stantially corresponding scanning position arrangements for the relatively higher definition receiver system &nd to, concurrently, repetitively define the scanning position arrangement for the relatively lower definition receiver system.

2. A television transmitter system as defined in claim 1 wherein said scanning means comprises: means for generating for said scanning means leftward and rightward scan excursions and upward and downward scan excursions with respect to scanning for the relatively lower definition receiver system to provide said plurality of different scanning position variations of the scanning position arrangement for the relatively lower definition receiver system.

SUBSTITUTE SHEET 80

3. A television transmitter system as defined in claim 2 wherein said scanning means genera- ting means comprises: means for generating for said scanning means successive leftward scan excursions and alternating upward and downward scan excursions with respect to scanning for the relatively lower definition receiver system to provide a first one of said plurality of different scanning position variations of the scanning position arrangement for the relatively lower definition receiver system; means for generating for said scanning means successive rightward scan excursions and alternating upward and downward scan excursions with respect to scanning for the relatively lower definition receiver - system, said upward and downward excursions being substantially 180 degrees out of phase with said upward and downward excursions for said first scanning position variation, to provide a second one of said plurality of different scanning position variations of the scanning position arrangement for the relatively lower definition receiver system; and means for generating for said scanning means successive leftward and rightward scan excursion instances and alternating upward and downward scan excursions with respect to scanning for the relatively lower definition receiver system to provide a third one of said plurality of different scanning position variations of the scanning position arrangement for the relatively lower definition receiver system.

HEET 81

4. A television transmitter system as defined in claim 1 wherein: said plurality of different scanning position variations provide successive groups of scanning positions, in substantially triangular configurations, along substantially sideways lines.

5. A television transmitter system as defined in claim 4 wherein: said substantially triangular configurations have the bases for said configurations alternately upwardly and downwardly oriented along said substantially sideways lines.

6. A television transmitter system as defined in claim 1 wherein: said video imaging signals for said plurality of different scanning position variations are sub- stantially in accord with the NTSC Standard^* for trans- mission over a channel substantially in accord with the. NTSC Standard; and said scanning means includes means to generate cycle synchronizing markers to mark cycles of said video imaging signals for said plurality of different scanning position variations.

SUBSTITUTE SHEET 82

7. An electrical visual image transmission system, comprising: imaging means to establish images for transmission; and means for electronically scanning, for said imaging means, a plurality of different scanning position variations of a scanning position arrangement on substantially straight lines, said plurality of different scanning position variations forming succes- sive groups of scanning positions, in substantially triangular configurations, along substantially straight lines.

8. A visual image transmission system as defined in claim 7 wherein said substantially triangular configurations have the bases for said configurations alternately substantially oppositely oriented along said substantially straight lines.

9. A television receiver system adapted to provide different degrees of spatial and time definition for different parts of its display images, comprising: display means to display images; means for scanning, for said display means, a plurality of different scanning position arrangements, said different scanning position arrangements having identified groups of scanning positions, each including a scanning position from each of said arrangements; memory means for receiving and storing groups of video imaging signals for said groups of scanning positions;

SUBSTITUTE SHEET 83

comparator means to compare update video imaging signals for scanning positions of said groups with signals for said positions from said stored signals to determine degrees of change between said update signals and said compared signals; and means for changing signals for scanning positions of said groups, from said stored signals, when said comparator means indicates degrees of change for other positions of said groups exceeding defined levels.

10. A television receiver system as defined in claim 9 wherein said memory means comprises: display memory means for receiving and storing groups of video imaging signals for said groups of scanning positions for generating said display images and for said changing by said changing means; and pre-display memory means for receiving and storing groups of video imaging signals for said groups of scanning positions for said comparing by said comparing means.

STITUTE SHEET 84

11. A relatively higher spatial definition television receiver system for transmitted video imaging signals which are concurrently for a relatively lower spatial definition receiver system, comprising: display means to display images; and means for scanning, for said display means, a plurality of different scanning position variations of a scanning position arrangement for the relatively lower spatial definition receiver system, to cyclically define said plurality of different scanning position variations according to video imaging signals for repetitively defining the scanning position arrangement for the relatively lower definition receiver system.

12. A television receiver system as defined in claim 11 wherein said scanning means comprises: means for generating for said scanning means leftward and rightward scan excursions and upward and downward scan excursions with respect to scanning for the relatively lower definition receiver system to provide said plurality of different scanning position variations of the scanning position arrangement for the_ relatively lower definition receiver system.

SUBSTITUTE SHEET 85

13. A television receiver system as defined in claim 12 wherein said scanning means genera- ting means comprises: means for generating for said scanning means successive leftward scan excursions and alternating upward and downward scan excursions with respect to scanning for the relatively lower definition receiver system to provide a first one of said plurality of different scanning position variations of the scanning position arrangement for the relatively lower definition receiver system; means for generating for said scanning means successive rightward scan excursions and alternating upward and downward scan excursions with respect to scanning for the relatively lower definition receiver system, said upward and downward excursions being substantially 180 degrees out of phase with said upward and downward excursions for said first scanning position variation, to provide a second one of said plurality of different scanning position variations of the scanning position arrangement for the relatively lower definition receiver system; and means for generating for said scanning means successive leftward and rightward scan excursion instances and alternating upward and downward scan excursions with respect to scanning for the relatively lower definition receiver system to provide a third one of said plurality of different scanning position variations of the scanning position arrangement for the relatively lower definition receiver system.

SUBSTITUTE SHEET 86

14. A television receiver system as defined in claim 11 wherein: said plurality of different scanning position variations provide successive groups of scanning positions, in substantially triangular configurations, along substantially sideways lines.

15. A television receiver system as defined in claim 14 wherein: said substantially triangular configurations have the bases for said configurations alternately upwardly and downwardly oriented along said sub- stantially sideways lines.

16. A television receiver system as defined in claim 11 wherein said plurality of different scanning position variations have identified groups of scanning positions, each including a scanning position from each of said variations, and further comprising:* memory means for receiving and storing groups of video imaging signals for said groups of scanning positions; comparator means to compare update video imaging signals for scanning positions of said groups with signals for said positions from said stored signals to determine degrees of change between said update signals and said compared signals; and means for changing signals for scanning positions of said groups, from said stored signals, when said comparator means indicates degrees of change for other positions of said groups exceeding defined levels.

HEET 87

17. A television receiver system as defined in claim 11 for transmitted video imaging signals which are substantially in accord with the NTSC Standard and include scanning cycle synchronizing markers, said transmission being over a channel substantially in accord with the NTSC standard, wherein: said scanning means includes means to detect occurrences of said scanning cycle synchronizing markers and to cycle said scanning of said different scanning position variations according to said occurrences.

18. An electrical visual image receiver system, comprising: display means to display images; and means for electronically scanning, for said display means, a plurality of different scanning position variations of a scanning position arrangement on substantially straight lines, said plurality of different scanning position variations forming succes- sive groups of scanning positions, in substantially triangular configurations, along substantially straight lines.

19. A visual image receiver system as defined in claim 18 wherein said substantially triangular configurations have the bases for said configurations alternately substantially oppositely oriented along said substantially straight lines.

SUBSTITUTE SHEET