Dialing apparatus for power failure extension telephone set of key telephone system
First Claim
1. A dialing apparatus for a power failure extension telephone set connected to a key service unit of a key telephone system, said telephone set being driven by power supplied through said key service unit in a power supply condition of said key service unit so as to function as an extension telephone set and being directly connected to an office telephone line in a power failure condition of said key service unit so as to function as an individual telephone set, comprising:
- a dial switch having a switch matrix of a single contact layer structure;
a control switch circuit connected to said dial switch and switched according to said power supply condition or said power failure condition of said key service unit;
a control circuit, activated by power from said key service unit in said power supply condition of said key service unit and connected to said dial switch via said control switch circuit, for detecting a state of said dial switch to transmit a control signal to said key service unit; and
a dial signal transmit circuit activated by power through said office telephone line in said power failure condition of said key service unit and connected to said dial switch via said control switch circuit, for detecting a state of said dial switch to transmit a call to said office telephone line.
1 Assignment
0 Petitions
Accused Products
Abstract
Disclosed is a dialing apparatus used for a power failure extension telephone set 30 in a key telephone system. The power failure extension telephone set 30 is driven by power supplied from a key service unit 2 so as to function as an extension telephone set when power is supplied to the key service unit 2, but directly connected to an office telephone line 1 so as to function as an individual telephone set when power is not supplied to the key service unit 2. The dialing apparatus comprises a dial switch 31 of single contact-layer structure and a control switch circuit 21 connected to the dial switch 31 and changed over according to the power supply or power failure condition of the key service unit. That is, when power is supplied to the key service unit 2, the control switch circuit 21 connects the dial switch 31 to a control circuit 19. This control circuit 19 is activated by power supplied from the key service unit 2 and detects the state of the dial switch to transmit a control signal to the key service unit. On the other hand, when power is not supplied to the key service unit 2, the control switch circuit 21 connects the dial switch 31 to a dial signal transmit circuit 20. This dial signal transmit circuit 20 is activated by power supplied through an office telephone line 1 and detects the state of the dial switch whenever a handset 16 is off-hooked, to transmit a call to the office telephone line 1.
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Citations
6 Claims
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1. A dialing apparatus for a power failure extension telephone set connected to a key service unit of a key telephone system, said telephone set being driven by power supplied through said key service unit in a power supply condition of said key service unit so as to function as an extension telephone set and being directly connected to an office telephone line in a power failure condition of said key service unit so as to function as an individual telephone set, comprising:
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a dial switch having a switch matrix of a single contact layer structure; a control switch circuit connected to said dial switch and switched according to said power supply condition or said power failure condition of said key service unit; a control circuit, activated by power from said key service unit in said power supply condition of said key service unit and connected to said dial switch via said control switch circuit, for detecting a state of said dial switch to transmit a control signal to said key service unit; and a dial signal transmit circuit activated by power through said office telephone line in said power failure condition of said key service unit and connected to said dial switch via said control switch circuit, for detecting a state of said dial switch to transmit a call to said office telephone line. - View Dependent Claims (2)
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3. A power failure extension telephone set connected to a key service unit of a key telephone system, said telephone set being driven by power supplied through said key service unit in a power supply condition of said key service unit so as to function as an extension telephone set and directly connected to an office telephone line in a power failure condition of said key service unit so as to function as an individual telephone set, comprising:
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a dial switch having a switch matrix of a single contact layer structure; a first control switch circuit connected to said dial switch and switched according to said power supply condition or said power failure condition of said key service unit; a control circuit, activated by power from said key service unit in said power supply condition of said key service unit and connected to said dial switch via said first control switch circuit, for detecting input signals from said dial switch to transmit a control signal to said key service unit; a dial signal transmit circuit, activated by power through said office telephone line in said power failure condition of said key service unit and connected to said dial switch via said first control switch circuit, for detecting input signals from said dial switch to transmit a call to said office telephone line; a second control switch circuit connected to a microphone and an earphone and switched according to said power supply condition or said power failure condition of said key service unit; a speech circuit, activated by power from said key service unit in said power supply condition and connected to said microphone and said earphone via said second control switch circuit, for connecting said microphone and earphone to said key service unit; and a telephone circuit, activated by power through said office telephone line in said power failure condition of said key service unit and connected to said microphone and said earphone via said second control switch circuit, for connecting said microphone and said earphone to said office telephone line. - View Dependent Claims (4, 5, 6)
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Specification