US3909550A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Key telephone systems
Assignee: International Components Corp
•
Filing: 1974-03-28
•
Granted: 1975-09-30
•
Expires: 1994-03-28
Abstract
Abstract The instant invention concerns an improvement for Touch Tone telephone systems. It provides a means for preventing false digit dialing of an other than intended station in the intercom or external paging mode. In Touch Tone systems, a receiver unit is employed which converts the frequencies representative of each digit dialed to a corresponding first logic output as well as a steering output each time a digit is dialed. The first logic output and the steering output are employed by the system to connect a calling station to a called station in the intercom Mode or to an external paging means, such as a loudspeaker, in the external paging mode. Touch Tone systems, since they operate in response to particular frequencies corresponding to particular digits, are responsive to background noise in the vicinity of the calling station. This can result in false dialing of an other than intended station. This invention provides relay means for interrupting the first logic output and steering output to preclude false dialing after a particular, intended station is called.
Inventors
- 👤 Ove Villadsen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 04:57
CPC Classifications
H; H04; H04Q; H04Q1/00; H04Q1/18; H04Q1/30; H04Q1/44; H04Q1/444; H04Q1/45; H04Q1/453
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
251 words
In a receiver unit for a key telephone system having an intercom and external paging mode said receiver unit including a translator circuit for converting frequencies representative of each digit dialed into a corresponding first logic output and which further provides a steering logic output for all digits dialed wherein said key telephone receiver is responsive to said first logic output and said steering logic output in combination such that said receiver connects a called station to a calling station when in said intercom mode after a predetermined number of digits are dialed or connects said calling station to external paging means after a predetermined digit or digits is dialed, each of said first logic outputs connected through corresponding switch contacts to a first common point when the corresponding digit is dialed, and said steering logic output connected to said first common point through corresponding switch contacts whenever any digit is dialed, the improvement which comprises: a. a second common point having a voltage potential corresponding to a first logic level; b. a first cutout switch contact connected in series between said first common point and said second common point; and c. means responsive to the dialing of said predetermined number of digits or said predetermined digit, for operating said first cutout switch contact, such that said cutout switch contact is opened after said predetermined number of digits or said predetermined digit is dialed, whereby said first logic outputs and said steering logic output are disconnected from said second common point.
Claim 2
Dependent Claim
251 words
In a receiver unit for a key telephone system having an intercom and external paging mode said receiver unit including a translator circuit for converting frequencies representative of each digit dialed into a corresponding first logic output and which further provides a steering logic output for all digits dialed wherein said key telephone receiver is responsive to said first logic output and said steering logic output in combination such that said receiver connects a called station to a calling station when in said intercom mode after a predetermined number of digits are dialed or connects said calling station to external paging means after a predetermined digit or digits is dialed, each of said first logic outputs connected through corresponding switch contacts to a first common point when the corresponding digit is dialed, and said steering logic output connected to said first common point through corresponding switch contacts whenever any digit is dialed, the improvement which comprises: a. a second common point having a voltage potential corresponding to a first logic level; b. a first cutout switch contact connected in series between said first common point and said second common point; and c. means responsive to the dialing of said predetermined number of digits or said predetermined digit, for operating said first cutout switch contact, such that said cutout switch contact is opened after said predetermined number of digits or said predetermined digit is dialed, whereby said first logic outputs and said steering logic output are disconnected from said second common point.
Claim 3
Dependent Claim
110 words
The improvement of claim 1 further comprising means for tone signalling the called stations including: a. a first set of switch contacts connected to the steering logic output and set in the closed position when the tone signalling digit is dialed; and b. a second cutout relay contact connected in series between said first set of switch contacts and said second common point, said second cutout relay contact set in the closed position when said first cutout relay contact is set in the opened position in the intercom or paging mode, whereby said steering logic output is connected to said first logic level when the tone signalling digit is dialed.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-09-29 | 1979-03-31 | 1979-09-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-09-29 | 1983-03-31 | 1983-09-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-09-29 | 1987-03-31 | 1987-09-30 | $7700.00 | Window Closed / Lapsed |