Patent US4611352A successfully refreshed from Google Patents.
US4611352A
Expired / Lapsed
US
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Optical transmission apparatus
Assignee: Panasonic Holdings Corp
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Filing: 1983-09-06
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Granted: 1986-09-09
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Expires: 2003-09-06
Abstract
Abstract An optical transmission apparatus is provided which has an LD of single longitudinal mode. A bias current of the LD is set at its threshold current. A current obtained by amplitude modulation of a signal to be transmitted is superposed on the bias current. The LD is then set in the multimode, so that the apparatus can transmit a high-quality signal with reduced modal noise and distortion during multimode fiber transmission.
Inventors
- 👤 Katsuyuki Fujito
- 👤 Hiroaki Nakata
- 👤 Takeshige Ichida
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 09:08
CPC Classifications
H; H04; H04B; H04B10/00; H04B10/25; H04B10/2581
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
221 words
An optical transmission apparatus comprising: clamp means for clamping an input video signal; high-frequency oscillator means for producing a high-frequency oscillation signal; amplitude modulator means for modulating the high-frequency oscillation signal with the clamped video signal to produce a modulated video signal; light emitting means for producing an output light signal in response to said modulated video signal from said amplitude modulator means; variable current source means for adding a current to said modulated video signal; said variable current source means providing a bias current to said light emitting means for substantially linear operation of said light emitting means, said bias current being substantially equal to a threshold current to adjust the current of said modulated video signal in response to said output light signal; multimode optical fiber means for transmitting said output light signal from said light emitting means; detecting means for photoelectriclaly converting at least part of the output light signal from said light emitting means into an electric signal; hold circuit means for holding a part of the electric signal from said detecting means which correspond to one of a pedestal and synctip period of the video signal; and comparator means for comparing an output from said hold circuit with a reference voltage and producing an output signal in response thereto to control said variable current source means.
Claim 2
Dependent Claim
221 words
An optical transmission apparatus comprising: clamp means for clamping an input video signal; high-frequency oscillator means for producing a high-frequency oscillation signal; amplitude modulator means for modulating the high-frequency oscillation signal with the clamped video signal to produce a modulated video signal; light emitting means for producing an output light signal in response to said modulated video signal from said amplitude modulator means; variable current source means for adding a current to said modulated video signal; said variable current source means providing a bias current to said light emitting means for substantially linear operation of said light emitting means, said bias current being substantially equal to a threshold current to adjust the current of said modulated video signal in response to said output light signal; multimode optical fiber means for transmitting said output light signal from said light emitting means; detecting means for photoelectriclaly converting at least part of the output light signal from said light emitting means into an electric signal; hold circuit means for holding a part of the electric signal from said detecting means which correspond to one of a pedestal and synctip period of the video signal; and comparator means for comparing an output from said hold circuit with a reference voltage and producing an output signal in response thereto to control said variable current source means.
Claim 3
Dependent Claim
15 words
An apparatus according to claim 1, wherein said hold circuit means comprises a sample/hold circuit.
Claim 4
Dependent Claim
47 words
An apparatus according to claim 1, further comprising an inductance series-connected with said light emitting means and said variable current source means, and a series circuit of impedancematching resistor means and DC blocking capacitor means is connected between said light emitting means and said amplitude modulator means.
Claim 5
Dependent Claim
62 words
An apparatus according to claim 1, wherein frequency f of said high-frequency oscillator means is set to satisfy a relation: f=(C/2nL)·(N+1/2) where c is the velocity of light, n is a refractive index of said fiber means, L is a distance from said light emitting means to an end face of a first connector connected thereto, and N is a positive integer.
Claim 6
Dependent Claim
173 words
An optical transmission apparatus comprising: clamp means for clamping an analog input video signal; high-frequency oscillator means for producing a high-frequency oscillation signal; amplitude modulator means for modulating the high-frequency oscillation signal with the clamped video signal to produce an analog modulated video signal; light emitting means for half-wave rectifying said analog modulated video signal and for producing an output light signal in response to a current of said modulated video signal from said amplitude modulator means which exceeds a threshold current of said light emitting means; variable current source means for adding a current to said modulated video signal; said variable current source means providing a bias current to said light emitting means to control the latter to operate in a substantially linear range of operation, said bias current being substantially equal to said threshold current to adjust the current of said modulated video signal in response to a DC component of said output light signal; and multimode optical fiber means for transmitting said output light signal from said light emitting means.
Claim 7
Dependent Claim
173 words
An optical transmission apparatus comprising: clamp means for clamping an analog input video signal; high-frequency oscillator means for producing a high-frequency oscillation signal; amplitude modulator means for modulating the high-frequency oscillation signal with the clamped video signal to produce an analog modulated video signal; light emitting means for half-wave rectifying said analog modulated video signal and for producing an output light signal in response to a current of said modulated video signal from said amplitude modulator means which exceeds a threshold current of said light emitting means; variable current source means for adding a current to said modulated video signal; said variable current source means providing a bias current to said light emitting means to control the latter to operate in a substantially linear range of operation, said bias current being substantially equal to said threshold current to adjust the current of said modulated video signal in response to a DC component of said output light signal; and multimode optical fiber means for transmitting said output light signal from said light emitting means.
Claim 8
Dependent Claim
140 words
An optical transmission apparatus comprising: clamp means for clamping an input video signal; high-frequency oscillator means for producing a high-frequency oscillation signal; amplitude modulator means for modulating the high-frequency oscillation signal with the clamped video signal to produce a modulated video signal; light emitting means for producing an output light signal in response to said modulated video signal from said amplitude modulator means; variable current source means for adding a current to said modulated video signal; said variable current source means providing a bias current to said light emitting means for substantially linear operation of said light emitting means, said bias current being substantially equal to a threshold current to adjust the current of said modulated video signal in response to said output light signal; multimode optical fiber means for transmitting said output light signal from said light emitting means.
Claim 9
Dependent Claim
140 words
An optical transmission apparatus comprising: clamp means for clamping an input video signal; high-frequency oscillator means for producing a high-frequency oscillation signal; amplitude modulator means for modulating the high-frequency oscillation signal with the clamped video signal to produce a modulated video signal; light emitting means for producing an output light signal in response to said modulated video signal from said amplitude modulator means; variable current source means for adding a current to said modulated video signal; said variable current source means providing a bias current to said light emitting means for substantially linear operation of said light emitting means, said bias current being substantially equal to a threshold current to adjust the current of said modulated video signal in response to said output light signal; multimode optical fiber means for transmitting said output light signal from said light emitting means.
Claim 10
Dependent Claim
198 words
An optical transmission apparatus comprising: clamp means for clamping an input video signal; high-frequency oscillator means for producing a high-frequency oscillation signal; amplitude modulator means for modulating the high-frequency oscillation signal with the clamped video signal to produce a modulated video signal; light emitting means for producing an output light signal in response to said modulated video signal from said amplitude modulator means; variable current source means for adding a current to said modulated video signal; said variable current source means providing a bias current to said light emitting means for substantially linear operation of said light emitting means, said bias current being substantially equal to a threshold current to adjust the current of said modulated video signal in response to said output light signal; multimode optical fiber means for transmitting said output light signal from said light emitting means; and wherein a frequency f of said high-frequency oscillator means is set to satisfy a relation: f=(C/nL)(N+1/2) where c is the velocity of light, n is a refractive index of said fiber means, L is a distance from said light emitting means to an end face of a first connector connected thereto, and N is a positive integer.
Claim 11
Dependent Claim
198 words
An optical transmission apparatus comprising: clamp means for clamping an input video signal; high-frequency oscillator means for producing a high-frequency oscillation signal; amplitude modulator means for modulating the high-frequency oscillation signal with the clamped video signal to produce a modulated video signal; light emitting means for producing an output light signal in response to said modulated video signal from said amplitude modulator means; variable current source means for adding a current to said modulated video signal; said variable current source means providing a bias current to said light emitting means for substantially linear operation of said light emitting means, said bias current being substantially equal to a threshold current to adjust the current of said modulated video signal in response to said output light signal; multimode optical fiber means for transmitting said output light signal from said light emitting means; and wherein a frequency f of said high-frequency oscillator means is set to satisfy a relation: f=(C/nL)(N+1/2) where c is the velocity of light, n is a refractive index of said fiber means, L is a distance from said light emitting means to an end face of a first connector connected thereto, and N is a positive integer.
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) | 1989-09-08 | 1990-03-10 | 1990-09-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-09-08 | 1994-03-10 | 1994-09-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-09-08 | 1998-03-10 | 1998-09-09 | $7700.00 | Window Closed / Lapsed |