The PANASONIC TX-25A3C is the first DIGITAL TELEVISION set From Panasonic TV models.
Until the coming of this model Panasonic was producing excellent analog technology tellyes.
With this model, Panasonic, is , like other high class fabricants, adopting the DIGIVISION ITT Digital Signal Processing Technology, using the ITT DIGIVISION DIGIT2000 Fast chipset improving furthermore picture quality and sound.
The television receiver has an alphanumeric display which appears on the picture tube screen, to give the user data on the tuned channel number, colour settings and other operating data. The digital processor which generates the characters for display also controls the channel setting, etc., under the control of a digital remote control unit . The processor has an associated memory circuit for permanent tuning back up. The control of the capacitance diode tuner is achieved by the processor altering the dividing factor of a feedback loop to a phase/frequency comparator . The other input to the comparator is a divided frequency from a quartz oscillator.
The PANASONIC TX-25A3C is a DIGITAL Colour television receiver or set , are known in which the majority of signal processing that takes place therein is carried out digitally. That is, a video or television signal is received in a conventional fashion using a known analog tuning circuit and then, following the tuning operation, the received analog television signal is converted into a digital signal and digitally processed before subsequently being converted back to an analog signal for display on a colour cathode ray tube.
In a conventional television receiver, all signals are analog-processed. Analog signal processing, however, has the problems at the video stage and thereafter. These problems stem from the general drawbacks of analog signal processing with regard to time-base operation, specifically, incomplete Y/C separation (which causes cross color and dot interference), various types of problems resulting in low picture quality, and low precision of synchronization. Furthermore, from the viewpoints of cost and ease of manufacturing the analog circuit, a hybrid configuration must be employed even if the main circuit comprises an IC. In addition to these disadvantages, many adjustments must be performed.
In order to solve the above problems, it is proposed to process all signals in a digital form from the video stage to the chrominance signal demodulation stage. In such a digital television receiver, various improvements in picture quality should result due to the advantages of digital signal processing.
Therefore digital television signal processing system introduced in 1984 by the Worldwide Semiconductor Group (Freiburg, West Germany) of International Telephone and Telegraph Corporation is described in an ITT Corporation publication titled "VLSI Digital TV System--DIGIT 2000." In that system color video signals, after being processed in digital (binary) form, are converted to analog form by means of digital-to-analog converters before being coupled to an image displaying kinescope. The analog color video signals are coupled to the kinescope via analog buffer amplifiers and video output kinescope driver amplifiers which provide video output signals at a high level suitable for driving intensity control electrodes of the kinescope.
The PANASONIC TX-25A3C Is a multistandard set and relates to a digital multistandard decoder for video signals and to a method for decoding video signals.
Colour video signals, so-called composite video, blanking and sync signals (CVBS) are essentially composed of a brightness signal or luminance component (Y), two colour difference signals or chrominance components (U, V or I, Q), vertical and horizontal sync signals (VS, HS) and a blanking signal (BL).
The different coding processes, e.g. NTSC, PAL and SECAM, introduced into the known colour television standards, differ in the nature of the chrominance transmission and in particular the different systems make use of different colour subcarrier frequencies and different line frequencies.
The following explanations relate to the PAL and NTSC systems, but correspondingly apply to video signals of other standards and non-standardized signals.
The colour subcarrier frequency (fsc) of a PAL system and a NTSC system is fsc(NTSC) = 3.58 MHz or fsc(PAL) = 4.43 MHz.
In addition, in PAL and NTSC systems the relationships of the colour subcarrier frequency (fsc) to the line frequency (fh) are given by fsc(NTSC) = 227.50 * fh or 4•fsc(NTSC) = 910 • fh fsc(PAL) = 283.75 * fh or 4•fsc(PAL) = 1135 • fh so that the phase of the colour subcarrier in the case of NTSC is changed by 180°/line and in PAL by 270°/line.
In the case of digital video signal processing and decoding the prior art fundamentally distinguishes between two system architectures. These are the burst-locked architecture and the line-locked architecture, i.e. systems which operate with sampling frequencies for the video signal, which are produced in phase-locked manner to the colour subcarrier frequency transmitted with the burst pulse or in phase-locked manner with the line frequency, respectively.
The principal advantage of the present invention is a color television receiver is provided having a fully digital color demodulator wherein the luminance signal and the chrominance signals are separated and digitally processed prior to being converted to analog signals in that the all-digital signal processing largely eliminates the need for nonintegratable circuit elements, i.e., particularly coils and capacitors, and that the subcircuits can be preferably implemented using integrated insulated-gate field-effect transistor circuits, i.e., so-called MOS technology. This technology is better suited for implementing digital circuits than the so-called bipolar technology.
The PANASONIC TX-25A3C is a multisound tv digital sound processing.
It has a DTI.(dti digital transient improvement pertains to a circuit for steepening color-signal transitions in color television receivers or the like particularly in DIGIVISION DIGIT2000 . ) circuit arrangement designed for use in digital color-television receivers or the like and contains for each of the two digital color-difference signals a slope detector to which both a digital signal defining an amplitude threshold value and a digital signal defining a time threshold value are applied. At least one intermediate value occurring during an edge to be steepened is stored, and at the same time value of the steepened edge, it is "inserted" into the latter.
The bandwidth of the color-difference channel is very small compared with the bandwidth of the luminance channel, namely only about 1/5 that of the luminance channel in the television standards now in use. This narrow bandwidth leads to blurred color transitions ("color edging") in case of sudden color-signal changes, e.g., at the edges of the usual color-bar test signal, because, compared with the associated luminance-signal transition, an approximately fivefold duration of the color-signal transition results from the narrow transmission bandwidth.
In the prior circuit arrangement, the relatively slowly rising color-signal edges are steepened by suitably delaying the color-difference signals and the luminance signal and steepening the edges of the color-difference signals at the end of the delay by suitable analog circuits. The color-difference signals and the luminance signal are present and processed in analog form as usual. This circuit arrangement is designed for use in digital color-television receivers or the like and contains for each of the two digital color-difference signals a slope detector to which both a digital signal defining an amplitude threshold value and a digital signal defining a time threshold value are applied. At least one intermediate value occurring during an edge to be steepened is stored, and at the same time value of the steepened edge, it is "inserted" into the latter. This is done by means of memories, switches, output registers, and a sequence controller.
ITT Semiconductors in W. Germany have been working on the application of digital techniques to basic TV receiver signal processing since 1977 with the supervision of the Engineer Micic Ljubomir, and at the recent Berlin Radio Show presented a set of digital chips for processing the video, audio and deflection signals in a TV receiver. The set consists of a' couple of l.s.i. and six v.l.s.i. chips - and by very large scale integration (v.l.s.i.) we're talking about chips that contain some more 200,000 transistors. What are the advantages?
For the setmaker, there's reduction in the component count and simpler, automated receiver alignment - alignment data is simply fed into a programmable memory in the receiver, which then adjusts itself. Subsequently, the use of feedback enables the set to maintain its performance as it ages. From the user's viewpoint, the advantages are improved performance and the fact that extra features such as picture -within -a -picture (two pictures on the screen at the same time) and still pictures become relatively simple to incorporate. The disadvantage of course is the need for a lot of extra circuitry. Since the received signals remain in analogue form, analogue -to -digital conversion is required before signal processing is undertaken. As the c.r.t. requires analogue drive signals, digital -to -analogue conversion is required prior to the RGB output stages - the situation is somewhat different in the timebase and audio departments, since the line drive is basically digital anyway and class D amplifier techniques can be used in the field and audio output stages. In between the A -D conversion and the various output stages, handling the signals in digital form calls for much more elaborate circuitry - hence those chips with 200,000 or so transistors. The extra circuitry is all incorporated within a handful of chips of course, but the big question is if and when the use of these chips will become an economic proposition, taking into account reduced receiver assembly/setting up costs, compared to the use of the present analogue technology - after all, colour receiver component counts are already very low. With the present digital technology, it's not feasible to convert the signals to digital form at i.f. So conversion takes place following video and sound demodulation. Fig. 1 shows in simple block diagram form the basic video and deflection signal processing arrangement used in the system devised by ITT Semiconductors. Before going into detail, two basic points have to be considered - the rate at which the incoming analogue signals are sampled for conversion to digital form, and the number of digits required for signal coding. Consider the example shown in Fig. 2. At both (a) and (b) the signals are sampled at times Ti, T2 etc. In (a) the signal is changing at a much faster rate than the sampling rate. So very little of the signal information would be present in the samples. In (b) the rate at which the signal is changing is much slower, and since the sampling rate is the same the samples will contain the signal information accurately. In practice, the sampling rate has to be at least twice the bandwidth of the signal being sampled. Once you've got your samples, the next question is how many digits are required for adequate resolution of the signal, i.e. how many steps are required on the vertical (signal level) scale in Fig. 2 The use of a four -digit code, i.e. 0000, 0001 etc., gives 16 possible signal levels. Doubling the number of digits to eight gives 256 signal levels and so on. ITT's experience shows that the luminance signal requires 8 bits (digits), the colour -difference signals require 6 bits, the audio signal requires 12 bits (14 for hi-fi quality) while 13 bits are required for a linear horizontal scan on a 26inch tube. These digital signals are handled as parallel data streams in the subsequent signal processing. Returning to Fig. 1, the A -D and D -A conversion required in the video channel is carried out by a single chip which ITT call the video codec (coder/decoder). A clock pulse generator i.c. is required to produce the various pulse trains necessary for the digital signal processing, and a control i.c. is used to act as a computer for the whole digital system and also to provide interfacing to enable the external controls (brightness, volume, colour etc.) to produce the desired effects. In addition, the control i.c. incorporates the digital channel selection system. The video codec i.c. uses parallel A-D/D-A conversion, i.e. a string of voltage comparators connected in parallel. This system places a high premium on the number of bits used to code the signal in digital form, so ITT have devised a technique of biasing the converter to achieve 8 -bit resolution using only 7 bits (the viewer's eye does some averaging on alternate lines, as with Simple PAL, but this time averaging luminance levels). The A -D comparators provide grey -encoded outputs, so the first stage in the video processor i.c. is a grey -to -binary transcoder. As Fig. 3 shows, the processes carried out in the video processor i.c. then follow the normal practice, though everything's done in digital form. The key to this processing is the use of digital filters. These are clocked at rates up to 18MHz, and provide delays, addition and multiplication. The glass chroma delay line required for PAL decoding in a conventional analogue decoder consists of blocks of RAM (random-access memory) occupying only three square millimeters of chip area each. As an example of the ingenuity of the ITT design, the digital delay line used for chroma signal averaging/separation in the PAL system is used in the NTSC version of the chip as a luminance/chrominance signal separating comb filter. Fig. 4 shows the basic processes carried out in the deflection processor i.c. This employs the sorts of techniques we're becoming used to in the latest generation of sync processor i.c.s. Digital video goes in, and the main outputs consist of a horizontal drive pulse plus drives to the field output and EW modulator circuits. The latter are produced by a pulse -width modulator arrangement, i.e. the sort of thing employed with class D output stages. The necessary gating and blanking pulses are also provided. A further chip provides audio signal processing. One might wonder why the relatively simple audio department calls for this sort of treatment. The W. German networks are already equipping themselves for dual -channel sound however, and the audio processor i.c. contains the circuitry required to sort out the two -carrier sound signals. These chips represent a major step in digitalizing the domestic TV receiver. It seems likely that some enterprising setmaker will in due course announce a "digital TV set". The interesting point then will be whether the chip yields, and the chip prices as production increases, will eventually make it worthwhile for all setmakers to follow this path (in 1984).
ADVANTAGE - Increased picture sharpness and highly improved signal-to-noise ratio.
The PANASONIC TX-25A3C was featuring in this model for sirst time an Adaptive Combifilter Video Processing:
Chrominance and luminance information can be separated by appropriately combing the composite signal spectrum. Known combing arrangements take advantage of the fact that the odd multiple relationship between chrominance signal components andhalf the line scanning frequency causes the chrominance signal components for corresponding image areas on successive lines to be 180.degree. out of phase with each other. Luminance signal components for corresponding image areas on successive linesare substantially in phase with each other.
All PANASONIC BIG sets from this to a time line of 10 12 Years are digital or even 100HZ Scan rate technology.
This set was quickly replaced with models fitting the new CHASSIS EURO-2 using the ITT DIGIT3000 chipset which you already seen here at Obsolete Tecnology Tellye Museum !
These were widely used by Panasonic until they decided in a brief time to drop all digital technology and return to analog CRT TUBE set employing the UOC 1 and the UOC 3 PHILIPS technology and then completely switch off to Flat Panels and Plasma sets.
The PANASONIC TX-25A3C set here shown has 25 Inches FSQ screen with black matrix and 100 Programs, Teletext, HIFI Stereo sound, Many connectivity sockets, Advanced OSD and many others features.
Needless to say: Picture is superb thanks even to a selected PHILIPS 45AX IMPROVED CRT TUBE, together with sound.
(Heavy set anyway).
Panasonic Corporation ( Panasonikku Kabushiki-gaisha) (TYO: 6752, NYSE: PC), formerly known as Matsushita Electric Industrial Co., Ltd. (, Matsushita Denki Sangyō Kabushiki-gaisha), is a Japanese multinational consumer electronics corporation headquartered in Kadoma, Osaka, Japan. Its main business is in electronics manufacturing and it produces products under a variety of names including Panasonic and Technics. Since its founding in 1918, it has grown to become the largest Japanese electronics producer. In addition to electronics, Panasonic offers non-electronic products and services such as home renovation services. Panasonic was ranked the 89th-largest company in the world in 2009 by the Forbes Global 2000 and is among the Worldwide Top 20 Semiconductor Sales Leaders !
HistoryPanasonic was founded in 1918 by Konosuke Matsushita first selling duplex lamp sockets. In 1927, it produced a bicycle lamp, the first product it marketed under the brand name National. It operated factories in Japan and other parts of Asia through the end of World War II, producing electrical components and appliances such as light fixtures, motors, and electric irons.
After World War II, Panasonic regrouped and began to supply the post war boom in Japan with radios and appliances, as well as bicycles. Matsushita's brother-in-law, Toshio Iue founded Sanyo as a subcontractor for components after WWII. Sanyo grew to become a competitor to Panasonic.
NameFor 90 years since establishment, the name of the company was always topped with ("Matsushita"). The company's name before 1 October 2008 had been "Matsushita Electric Industrial Co., Ltd.", used since 1935.
In 1927, the company founder adopted a brand name "National" ( National) for a new lamp product, knowing "national" meant "of or relating to a people, a nation." In 1955, the company labeled its export audio speakers and lamps "PanaSonic", which was the first time it used its "Panasonic" brand name.
The company began to use a brand name "Technics" in 1965. The use of multiple brands lasted for some decades.
In May 2003, the company put "Panasonic" as its global brand, and set its global brand slogan, "Panasonic ideas for life." The company began to unify its brands to "Panasonic" and, by March 2004 replaced "National" for products and outdoor signboards, except for those in Japan.
On January 10, 2008, the company announced that it would change its name to "Panasonic Corporation" (effective on October 1, 2008) and phase out the brand "National" in Japan, replacing it with the global brand "Panasonic" (by March 2010). The name change was approved at a shareholders' meeting on June 26, 2008 after consultation with the Matsushita family. Panasonic owns RCTI, Global TV and MNC TV.
ElectronicsIn 1961, Konosuke Matsushita traveled to the United States and met with American dealers. Panasonic began producing television sets for the U.S. market under the Panasonic brand name, and expanded the use of the brand to Europe in 1979.
The company used the National trademark outside of North America during the 1950s through the 1970s. (The trademark could not be used probably due to discriminatory application of trademark laws where brands like General Motors were registrable.) It sold televisions, hi-fidelity stereo receivers, multi-band shortwave radios, and marine radio direction finders, often exported to North America under various U.S. brand names. The company also developed a line of home appliances such as rice cookers for the Japanese and Asian markets. Rapid growth resulted in the company opening manufacturing plants around the world. National/Panasonic quickly developed a reputation for well-made, reliable products.
The company debuted a hi-fidelity audio speaker in Japan in 1965 with the brand Technics. This line of high quality stereo components became worldwide favorites. The most famous product still made today is the SL-1200 record player, known for its high performance, precision, and durability. Throughout the 1970s and early 1980s, Panasonic continued to produce high-quality specialized electronics for niche markets such as shortwave radios, as well as developing a successful line of stereo receivers, CD players, and other components.
Since 2004, Toyota has used Panasonic batteries for its Toyota Prius, an environmentally friendly car made in Japan.
On January 19, 2006 Panasonic announced that, starting in February, it will stop producing analog televisions (then 30% of its total TV business) to concentrate on digital TVs.
On November 3, 2008 Panasonic and Sanyo were in talks, resulting in the eventual acquisition of Sanyo. The merger was completed in December 2009, and resulted in a mega-corporation with revenues over ¥11.2 trillion (around $110 billion). As part of what will be Japan's biggest electronics company, the Sanyo brand and most of the employees will be retained as a subsidiary.
In November 1999, the Japan Times reported that Panasonic planned to develop a "next generation first aid kit" called the Electronic Health Checker. At the time, the target market was said to be elderly people, especially those living in rural areas where medical help might not be immediately available, so it was planned that the kit would include support for telemedicine. The kits were then in the testing stage, with plans for eventual overseas distribution, to include the United States.
In recent years the company has been involved with the development of high-density optical disc standards intended to eventually replace the DVD and the SD memory card.
On July 29, 2010 Panasonic reached an agreement to acquire the remaining shares of Panasonic Electric Works and Sanyo shares for $9.4 billion.