Receiver device for receiving ringing signals in an off-hook line condition

• US 5,390,249 A
• Filed: 01/14/1992
• Issued: 02/14/1995
• Est. Priority Date: 03/14/1991
• Status: Expired due to Term

• Current Assignee: Chung H. Park
• Original Assignee: Chung H. Park
• Inventors: Park, Chung H.
• Primary Examiner(s): NOT, DEFINED
• Assistant Examiner(s): Shehata, M.
• Application Number:
  US07/820,034
• Time in Patent Office: 1,127 Days
• Field of Search: 379/387, 379/393, 379/377, 379/386
• US Class Current: 379/393
• CPC Class Codes: H04M 1/82 Line monitoring circuits for call progress or status discrimination for detecting caller identity H04M1/573
• CPC Class Codes: H04M 19/04 the ringing-current being generated at the substations
• CPC Class Codes: H04M 3/14 Signalling existence of persistent "off-hook" condition

Abstract

A telephone communication enable state maintaining circuit is disclosed, and the circuit includes a communication circuit 10, a communication operating circuit 20 and an operation maintaining circuit 30. The communication circuit 10 includes contacts 3,4,5, and a condenser C₁. The communication operating circuit 20 includes a resistor r₁, a condenser C₂, a transistor 6 and contacts R₃ a, R₃ b, R₁ a, R₁ b. The operation maintaining circuit 30 includes contacts R₁ c, R₃ c, a resistor r₂, a condenser C₃, and a transistor 7. According to the present invention, telephone calls from the outside can be received, even if the telephone receiver is placed in an abnormal manner.

Claims

1. A telephone communication circuit comprising:

a first communication circuit (10) comprising;

a first hook switch (1) connected to a first telephone lead line,

a second hook switch (2) connected to said first hook switch (1), and connected to a positive line of a circuit operating line VDC, wherein said first hook switch and said second hook switch are operated in the same manner,

a first switch (3) of a first relay (R₁),

a first switch (4) of a second relay (R₂),

a first switch (5) of a third relay (R₃), wherein said first switches of said first, second, and third relays are connected in parallel between said first hook switch (1) and a parallel connection of said first relay and a first condenser, said parallel connection connected between said first switches of said first, second, and third relays and a telephone circuit;

a communication operating circuit (20) comprising;

a first side of said first relay and a first side of said second relay (R₂ and R₃) connected to said positive line of a circuit operating line VDC,

a first contact of a second switch (R₃ a) of said third relay (R₃) connected to said positive line of said circuit operating line VDC, said second relay, and said third relay (R₂ and R₃);

a second contact of said second switch (R3b) of said third relay (R₃) connected to a first contact of a second switch (R1a) of said first relay (R₁); and

a second contact of said second switch (R1b) of said first relay (R₁) for being electrically connected to said first contact of said second switch (R₃ a) of said third relay such that when said first and second relays are not operated, a circuit is completed between said positive line of said circuit operating line VDC, said first contact of said second switch of said first relay being connected to a base of a first transistor through a first resistor and through a first condenser to a collector of said first transistor and a negative line of said circuit operating line VDC, said first transistor operating said relay R₂ ; and

an operation maintaining circuit 30 comprising;

a third contact of said second switch of said third relay,

a third contact of said second switch of said first relay connected to said third contact said second switch of said third relay and to a base of a second transistor through a second resistor and through a second condenser to a collector of said second transistor and said negative line of said operating VDC, such that when said third relay is operated a circuit is made from said positive line of said circuit operating line VDC to said third contact of said second switch of said third relay and when said first relay is operated, said first contact of said second switch of said first relay is connected to said third contact of said second switch of said first relay.

2. The telephone communication enable state maintaining circuit as claimed in claim 1, wherein push button switches 1 and 2 are used in place of said hook switches 1 and 2.

3. A telephone communication circuit comprising:

a communication circuit connected to a first telephone lead line though a first hook switch including a first, a second, and a third switch connected in parallel, the parallel connection connected in series with a first relay to a telephone circuit such that when the first hook switch is operated, the first telephone lead line is connected to the telephone circuit through the third switch and the first relay and when the first relay is operated, the first switch is closed and when a line parking signal has been received by the communication circuit from a telephone bureau that stops a current flowing through the first relay and the first hook switch is not opened, the first relay causes the first switch to open thereby breaking the connection from the first telephone lead line to the telephone circuit;

a communication operating circuit including a second hook switch, operated together with the first hook switch, and a second relay such that when the second hook switch is operated, the second relay is operated to close the second switch to maintain a connection between the first telephone lead line and the telephone circuit;

an operation maintaining circuit including a third relay such that when the second hook switch is operated, the third relay causes the third switch to open; and

a telephone signal generating section connected to a first and a second telephone lead line.