Television – Format conversion – Conversion between standards with different aspect ratios
Reexamination Certificate
1996-08-02
2002-05-28
Kostak, Victor R. (Department: 2611)
Television
Format conversion
Conversion between standards with different aspect ratios
C348S446000, C348S556000, C348S558000
Reexamination Certificate
active
06396542
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to television receivers for high-definition television HDTV) signals.
In a television receiver the greater the number of scan lines in a given frame time (33.3 mS in the U.S. and 40 mS in Europe), the greater the power consumption involved in the magnetic deflection system for the kinescope. In large-screen television receivers for receiving television signals broadcast in accordance with current standards (such as the NTSC standard), so as to use field-to-field line-interlace, an approximation to progressive scan is made by time-compressing the scan lines to half duration and inserting intermediate scan lines generated by interpolation. This procedure doubles the number of scan lines per frame, thereby doubling horizontal and vertical sweep rates and increasing the power consumption of the magnetic deflection system for the kinescope by a factor of four.
High-definition television radio-frequency (RF) signals currently proposed for adoption as a future standard for broadcasting television in the United States are descriptive of digital data. The digital data detected from the HDTV RF signals are descriptions of successive image fields coded essentially in accordance with the MPEG-2 Standard, which descriptions are decoded to recover the raster-scanned video signals. The raster scanning will include a larger number of scan lines than the current NTSC television broadcast standard and may be progressive in nature, rather than line-interlaced as in the current NTSC television broadcast standard. Currently, proposals for 720 progressively scanned scan lines of television image per 60 Hz frame and for 1080 line-interlaced scan lines of television image per 30 Hz frame are being considered. A number of inactive lines must be included in each frame to allow for vertical retrace, so there are totals of about 787.5 lines in the progressively scanned HDTV signal and of about 1125 lines in the line-interlaced HDTV signal. The concerns of the systems designers have been primarily directed to the problems of keeping transmission bandwidth requirements within prescribed limits.
The current standard for HDTV television broadcasting in the UHF television band uses 8-level vestigial sideband (VSB) amplitude modulation of a suppressed-carrier located 310 kHz from the edge of the 6 MHz-wide television channel, and a pilot carrier accompanies the vestigial sideband. Cablecast practice for HDTV television broadcasting is expected to use 16- or 32-state QAM of a mid-channel suppressed carrier, however, with no accompanying pilot carrier. The format for the digital data descriptive of the HDTV display is expected to be the same in cablecast practice as in HDTV broadcasting, or substantially so. The digital data are transmitted in packets, header information in certain of the packets identifying those packets of data that are descriptive of the video portions of a received HDTV program. The digital data are not directly descriptive of the raster scanning of image frames and a digital HDTV receiver generally includes a plurality of dual-ported frame-store display buffer memories, each with a random-access port used for updating the stored image therein and each with a serial output port from which selected lines of data can be read in a shift register operation. Since the luminance signal has more lines per field and has more pixels per scan line than the color-difference signals, the descriptions of the color-difference signals are advantageously stored in dual-ported frame-store buffer memories which are separate from those that store the descriptions of the luminance signals and which are addressed less frequently. During each display field, the ones of these frame-store display buffer memories used for storing descriptions of the current display field in terms of luminance and color-difference video signals supply these descriptions in raster-scan order from their serial output ports.
With the digital standard for broadcasting television in the United States being largely worked out, the time is at hand for considering the problems associated with the commercial production of receivers. Receivers that are capable of receiving transmissions whether in accordance with the former NTSC standard, in accordance with the new digital HDTV broadcast standard, or in accordance with the digital HDTV cablecast practice are desirable. For each individual manufacturer, there are substantial economies associated with the use of similar components across its entire television receiver line. Preferably, a small-screen bottom-of-the-line television receiver with detachable side speakers will use the same digital processing circuitry and buffer memory to generate high-definition luminance and chrominance signals that are used by a top-of-the-line television receiver using a full-wall display unit and a surround-sound speaker system.
When HDTV broadcasts are made, it is likely that some people will desire to receive these broadcasts on small-screen television receivers, some of which will be of portable battery-powered type. The primary interest will be to be able to view video programs transmitted in 16:9 width-to-height ratio. In these small-screen television receivers, the improved spatial and temporal resolution afforded by HDTV transmission will be of no importance at normal viewing distances. Indeed, in kinescopes that use color mask apertures screens, the limitations on smallness of apertures may limit available spatial resolution to less than that broadcast. On the other hand, there is a significant increase in the power consumption in the magnetic deflection system for the kinescope responsive to the faster sweep rates. Since the major portion of the TV receiver power consumption is consumed by the kinescope deflection system, high sweep rates are very disadvantageous in a small-screen TV receiver that is battery-powered. A heavy battery is required if more than a few minutes of viewing time are to be provided before the battery needs to be recharged.
A kinescope which displays a 480-active-scan-line frame with field interlace and with a 16:9 aspect ratio will require nearly twice the deflection power of a kinescope of the same screen height which displays a 480-active-scan-line frame with field interlace and with a 4:3 aspect ratio. The additional power is required for sweeping through the one-third longer scan line in the same scan line period. The deflection angle is related to magnetic field strength and thus to the current in the deflection coils; and the rate of change in the current through the deflection coils depends on the voltage applied thereto. While the horizontal deflection coils are normally resonated to recover energy stored therein, there are I
2
R losses in the resistance of the deflection coil windings and more significantly there are losses in the deflection amplifiers used to drive the deflection coils which latter losses are related to the square of the driving voltages.
A kinescope which displays a 480-active-scan-line frame scanned in one-thirtieth second with field interlace and with a 16:9 aspect ratio will consume about one-fifth the power of a kinescope of the same screen height which displays a 1080-active-scan-line frame scanned in one-thirtieth second with field interlace and with a 9:16 aspect ratio, however. Not only are horizontal deflection power requirements about one-fifth; so are vertical deflection power requirements. A kinescope which displays a 480-active-scan-line frame scanned in one-thirtieth second with field interlace and with a 16:9 aspect ratio will consume about one-36th the power of a kinescope of the same screen size which displays a 720-active-scan-line progressively scanned (i.e. without field interlace) frame in one-sixtieth second with a 16:9 aspect ratio. Not only are horizontal deflection power requirements about one-36th; so are vertical deflection power requirements. The energy stored in the vertical deflection coils customarily is not recovered by resonating them, owing to the low resonant freque
Kostak Victor R.
Samsung Electronics Co,. Ltd.
Sughrue & Mion, PLLC
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