Inventors soon picked up on the potential for this and from 1879. Patents for systems flooded in. At this time several, 26 in fact, patents were filed for various dial and push-button telephones.
How do rotary telephones work
While the actual use of a rotary dial phone is pretty straightforward, the gubbins was pretty complicated. In a fundemental sense, as each number was dialed the electromechanical system underneath it all would record many electrical pulses made as the dial returned to its starting position.
If you have an old rotary dial phone lying around the house or fancy adding a touch of retro-tech to your home, you might have wondered if it might actually work today? The answer might actually surprise you, though it does depend on your service provider.
A rotary dial is a component of a telephone or a telephone switchboard that implements a signaling technology in telecommunications known as pulse dialing. It is used when initiating a telephone call to transmit the destination telephone number to a telephone exchange.
On the rotary dial, the digits are arranged in a circular layout, with one finger hole in the finger wheel for each digit. For dialing a digit, the wheel is rotated against spring tension with one finger positioned in the corresponding hole, pulling the wheel with the finger to a stop position given by a mechanical barrier, the finger stop. When released at the finger stop, the wheel returns to its home position driven by the spring at a speed regulated by a governor device. During this return rotation, an electrical switch interrupts the direct current (DC) of the telephone line (local loop) the specific number of times associated with each digit and thereby generates electrical pulses which the telephone exchange decodes into each dialed digit. Thus, each of the ten digits is encoded in sequences to correspond to the number of pulses; thus, the method is sometimes called decadic dialing.
The first patent for a rotary dial was granted to Almon Brown Strowger on November 29, 1892, but the commonly known form with holes in the finger wheel was not introduced until about 1904.[citation needed] While used in telephone systems of the independent telephone companies, rotary dial service in the Bell System in the United States was not common until the early 1920s.[1]
From the 1960s onward, the rotary dial was gradually supplanted by DTMF (dual-tone multi-frequency) push-button dialing, first introduced to the public at the 1962 World's Fair under the trade name "Touch-Tone". Touch-tone technology primarily used a keypad in the form of a rectangular array of push-buttons. Although no longer in common use, the rotary dial's legacy remains in the verb "to dial (a telephone number)".
The first commercial installation of a telephone dial accompanied the first commercial installation of a 99-line automatic telephone exchange in La Porte, Indiana, in 1892, which was based on the 1891 Strowger designs. The original dials required complex operational sequences. A workable, albeit error-prone, system was invented by the Automatic Electric Company using three push-buttons on the telephone. These buttons represented the hundreds, tens, and single units of a telephone number. When calling the subscriber number 163, for example, the user had to push the hundreds button once, followed by six presses of the tens button, and three presses of the units button.[3] In 1896, this system was supplanted by an automatic contact-making machine, or calling device. Further development continued during the 1890s and the early 1900s in conjunction with improvements in switching technology.
Almon Brown Strowger was the first to file a patent for a rotary dial on December 21, 1891, which was awarded on November 29, 1892, as U.S. Patent 486,909.[4][5] The early rotary dials used lugs on a finger plate instead of holes, and did not produce a linear sequence of pulses, but interrupted two independent circuits for control of relays in the exchange switch. The pulse train was generated without the control of spring action or a governor on the forward movement of the wheel, which proved to be difficult to operate correctly.
Despite their lack of modern features, rotary dials occasionally find special uses, particularly in industrial equipment. For instance, the anti-drug Fairlawn Coalition of the Anacostia section of Washington, D.C., persuaded the phone company to reinstall rotary-dial pay phones in the 1980s to discourage loitering by drug purchasers, since they lacked a telephone keypad to leave messages on dealers' pagers.[6] They are also retained for authenticity in historic properties such as the U.S. Route 66 Blue Swallow Motel, which date back to the era of named exchanges and pulse dialing.[7]
A rotary dial typically features a circular construction. The shaft that actuates the mechanical switching mechanism is driven by the finger wheel, a disk that has ten finger holes aligned close to the circumference. The finger wheel may be transparent or opaque permitting the viewing of the face plate, or number plate below, either in whole, or only showing the number assignment for each finger hole. The faceplate is printed with numbers, and sometimes letters, corresponding to each finger hole. The 1 is normally set at approximately 60 degrees clockwise from the uppermost point of the dial, or approximately at the 2 o'clock position, and then the numbers progress counterclockwise, with the 0 being at about 5 o'clock.[citation needed] A curved device called a finger stop sits above the dial at approximately the 4 o'clock position. The physical nature of the dialing mechanism on rotary phones allowed the use of physical locking mechanisms to prevent unauthorized use. The lock could be integral to the phone itself or a separate device inserted through the finger hole nearest the finger stop to prevent the dial from rotating.
Early dials worked by direct or forward action. The pulses were generated as the dial turned toward the finger stop position. When the user's hand motion was erratic, it produced the wrong numbers. In the late 19th century, the dial was refined to operate automatically by a recoil spring. The user selected the digit to be dialed, rotated the dial to the finger stop, then released it. The spring caused the dial to rotate back to its home position during which time constant speed was maintained with a centrifugal governor.
The rotary dial governor is subject to wear and aging, and may require periodic cleaning, lubrication and adjustment by a telephone technician. In the video, the green LED shows the dial impulse pulses and the red LED shows the dial's off-normal contact function.
Some telephones include a small dial built into the handset, with a movable finger stop. The user rotates the dial clockwise until the finger stop ceases moving, then releases both. In this design the holes extend around the full circumference of the dial, allowing a reduced diameter. This was introduced by Western Electric on the compact Trimline telephone, the first to locate the dial in the handset. In Spain, such phones were manufactured for CTNE (Compañía Telefónica Nacional de España) by Málaga-based factory "CITESA", being named as "Góndola" phones by its particular shape. Spanish Góndola sets were fitted from the beginning with a red LED series connected with the line, allowing the dial ("disco" in Spanish) to be backlit while dialling. For that, the LED was bridged by an anti-parallel Zener diode, to allow the DC to pass even if the line polarity were reversed. In case of line polarity reversal, the LED would not light, but the phone would work anyway. The LED and Zener diode were contained in the same package for ease of assembly in manufacturing.
Before 1960 Australian rotary dial telephones had each number's corresponding letter printed on a paper disc in the centre of the plate, with space where the subscriber could add the phone number. The paper was protected by a clear plastic disc, held in place by a form of retaining ring which also served to locate the disc radially. The Australian letter-to-number mapping was A=1, B=2, F=3, J=4, L=5, M=6, U=7, W=8, X=9, Y=0, so the phone number BX 3701 was in fact 29 3701. When Australia around 1960 changed to all-numeric telephone dials, a mnemonic to help people associate letters with numbers was the sentence, "All Big Fish Jump Like Mad Under Water eXcept Yabbies."
Even after the transition to DTMF dialing with push-button keypads in most areas, pulse-dialing telephones continued to be produced for some time, even with keypads for dialing, for use with certain private exchange systems.[12][failed verification] Some of these can be distinguished visually by the lack of keys with the symbols # and *. Some telephones may have an option to select pulse dialing or DTMF dialing.
One of the relative miracles of modern times is the reliability of the phone system. The power goes out fairly often for most people. Sometimes it is only out for a second, but other times it can be out for minutes, hours or even days. Your telephone, on the other hand, is always working (as long as you pay the bill). Why is that?
The article How Telephones Work talks about the simplicity of phones and the telephone network. The article shows you how, with just a 9-volt battery and a resistor, you can create your own intercom system using two normal telephones. A phone will work as long as it is getting between 6 and 12 volts at about 30 milliamps. In other words, it takes very little power to operate a telephone.
You are probably already aware of what a rotary dial telephone looks like. Perhaps you have seen the telephone in an old movie or at an uncommon thrift store, but have you ever wondered how the old school phone made its calls? The rotary telephone was introduced to the public in the early 1900s, with the finger wheel design making its world debut in 1904. Eventually, push buttons were introduced to the telephone model and the rotary dial fell completely out of fashion around the 1980s. 2ff7e9595c
コメント