Abstract: A TFT substrate is provided near its outer periphery with a metallic wiring and pad portions, and a conductive light-shielding film is provided on the outside of these. The conductive light-shielding film is left annularly along the outer peripheral portion of the TFT substrate so that, when an upper layer light-shielding film is formed on the TFT substrate, the upper layer light-shielding film on the scribed line side would not easily be exfoliated at the time of etching or cleaning. Of the conductive light-shielding film, the position of the conductive light-shielding film disposed on the outside of the pad portions is shifted to the outer side so that the spacing between the conductive light-shielding film and the pad portions is set to be, for example, not less than 10 &mgr;m. By this, electrostatic trouble between the conductive light-shielding film and the pad portions is restrained.

Abstract: Pin fraud of battery reversal pulse metered sophisticated coin telephones is detected, an announcement of the detected fraud made, and the fraud is stopped if the detected fraud continues by the method and apparatus of the invention. By carefully monitoring within the switch office the loop current that is flowing in the 48 volt battery circuit, especially in the more positive terminal portion of the 48 volt battery circuit, loss of current to a fraud ground at a remote coin telephone can be detected. Once a fraud ground is detected, an announcement is made to at least the calling station where the pin fraud was detected, which says in effect "The pay telephone you are using is charging improperly for the service provided. If such improper charging continues the present call will be discontinued." A convenient location in the switch office and an inexpensive component configuration make the addition of this pin fraud detection, announcement and prevention apparatus very cost effective.

Abstract: Pin fraud of battery reversal pulse metered sophisticated coin telephones is detected and prevented by the method and apparatus of the invention. By carefully monitoring within the switch office the loop current that is flowing in the 48 volt battery circuit, especially in the more positive terminal portion of the 48 volt battery circuit, loss of current to a fraud ground at a remote coin telephone can be detected. Once a fraud ground is detected, the call is terminated. The current detector of this method and apparatus can also be used to terminate a call for the normal on-hook break of the loop current. A convenient location in the switch office and an inexpensive component configuration make the addition of this pin fraud detection and prevention apparatus very cost effective.

Abstract: A method and apparatus for telephone call answer supervision, capable of detecting the completion of both national and international calls, which employ different answer confirmation formats, and provide confirmation that a placed call has been answered if least one of the following conditions occurs: 1) a tone of a given frequency, transmitted on the transmit line of a telephone, is detected as received back on the receive line; and 2) audio activity having a non-repetitive cadence is detected on both the transmit and receive lines of the telephone. Also provided is an autonomous pay telephone, such as a mobile telephone, which includes an arrangement for determining and accessing a call rate, per unit of time, for a call placed to a given telephone number, a display for displaying, in real-time as the call progresses, charges for a completed call as well as an accounting arrangement for storing charges accessed for each completed call.

Abstract: A call progress circuit for both a customer owned, coin operated telephone and a regulated telephone is provided that does not mute the paystation's transmitter, so that voice signals from the calling party may be heard by the called party, thereby preventing an answering party from hanging up prematurely. The call progress circuit employs a transmitter-sourced audio signal discriminator which monitors audio signals placed on the line from the called station, the calling paystation and a central office, and controllably removes or subtracts out those audio signals that originate at the paystation transmitter. The discriminator includes a pair of tunable bandpass filters respectively associated with a telephone line receiver and the paystation transmitter circuit. Coupled to these filters is an audio spectrum scanner which sequentially adjusts the sensitivity characteristics of the filters.

Abstract: An interface (10) is disclosed for coupling a conventional pay station telephone (12) to a telephone switching system (16). The interface (10) provides supervision signal detection functions normally provided by a switching system, and thus can be connected thereto by a less costly business line (28). The interface includes processor controlled tone generators (72, 76) and detectors (73, 74, 81, 106, 108) for detecting tones and voltages transmitted by either the telephone (12) or the switching system (16). The interface (10) further includes a detector (106) and a procedure (FIG. 8) for providing an answer call indication. Coin collection or return is controlled by the interface (10) depending on the status of the call which is also determined by the interface (10).