Patent US5796767A successfully refreshed from Google Patents.
US5796767A
Expired / Lapsed
US
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Driver circuit of light-emitting device
Assignee: NEC Corp
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Filing: 1997-02-20
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Granted: 1998-08-18
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Expires: 2017-02-20
Abstract
Abstract A driver circuit of a light-emitting device that is able to reduce the current consumption. This circuit includes a reference current source for generating a reference current, a cascode current source circuit for generating a driving current for the light-emitting device with the use of the reference current, and an input circuit for switching the driving current according to a data signal. The cascode current source circuit has a first current mirror formed by first and second transistors and a second current mirror formed by third and fourth transistors. The first transistor is supplied with a first constant current proportional to the reference current, and controls the second transistor so that the driving current flows through the second transistor. The third transistor is supplied with a second constant current proportional to the reference current, and generates a mirror current with respect to the second constant current. The second mirror current flows through the second transistor as the driving current. The input circuit serves to turn on and off the fourth transistor according to the data signal, thereby controlling the output of the driving current to the light-emitting device.
Inventors
- 👤 Yukio Aizawa
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 13:57
CPC Classifications
G; G05; G05F; G05F3/00; G05F3/02; G05F3/08; G05F3/10; G05F3/16; G05F3/20; G05F3/24; G05F3/242; H; H01; H01S; H01S5/00; H01S5/04; H01S5/042; H05; H05B; H05B45/00; H05B45/30; H05B45/395; H05B45/397; H01S5/0428; Y; Y02; Y02B; Y02B20/00; Y02B20/30
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
187 words
A driver circuit of a light-emitting device comprising: a reference current source for generating a reference current; a cascode current source circuit for generating a driving current for said light-emitting device with the use of said reference current; an input circuit for switching said driving current according to a data signal; said cascode current source circuit having a first current mirror formed by first and second transistors and a second current mirror formed by third and fourth transistors; said first transistor of said first current mirror being supplied with a first constant current proportional to said reference current, and controlling said second transistor so that said driving current flows through said second transistor; said third transistor of said second current mirror being supplied with a second constant current proportional to said reference current, and generating a mirror current with respect to said second constant current; said second mirror current flowing through said fourth transistor as said driving current; said input circuit serving to turn on and off said fourth transistor according to said data signal, thereby controlling said output of said driving current to said light-emitting device.
Claim 2
Dependent Claim
187 words
A driver circuit of a light-emitting device comprising: a reference current source for generating a reference current; a cascode current source circuit for generating a driving current for said light-emitting device with the use of said reference current; an input circuit for switching said driving current according to a data signal; said cascode current source circuit having a first current mirror formed by first and second transistors and a second current mirror formed by third and fourth transistors; said first transistor of said first current mirror being supplied with a first constant current proportional to said reference current, and controlling said second transistor so that said driving current flows through said second transistor; said third transistor of said second current mirror being supplied with a second constant current proportional to said reference current, and generating a mirror current with respect to said second constant current; said second mirror current flowing through said fourth transistor as said driving current; said input circuit serving to turn on and off said fourth transistor according to said data signal, thereby controlling said output of said driving current to said light-emitting device.
Claim 3
Dependent Claim
46 words
A circuit as claimed in claim 1, wherein said first transistor of said first current mirror is supplied with said first constant current through a transistor; and wherein said third transistor of said second current mirror is supplied with said second constant current through another transistor.
Claim 4
Dependent Claim
53 words
A circuit as claimed in claim 1, wherein said first transistor of said first current mirror is supplied with said first constant current through a transistor; and wherein said third transistor of said second current mirror is supplied with said second constant current through the same transistor as that of said first transistor.
Claim 5
Dependent Claim
108 words
A circuit as claimed in claim 1, wherein said input circuit includes a timing circuit and fifth and sixth transistors; and wherein said fifth transistor serves as a switch for turning on or off the control of said fourth transistor of said second current mirror by said third transistor of said second current mirror; and wherein said fifth transistor is driven by a first timing signal from said timing circuit; and wherein said sixth transistor serves as a switch for turning on or off said fourth transistor of said second current mirror; and wherein said sixth transistor is driven by a second timing signal from said timing circuit.
Claim 6
Dependent Claim
18 words
A circuit as claimed in claim 4, wherein said first and second timing signals have a time delay.
Claim 7
Dependent Claim
45 words
A circuit as claimed in claims 4, wherein said timing circuit of said input circuit includes cascaded inverters; and wherein said first timing signal is derived from an output of said inverters, and said second timing signal is derived from another output of said inverters.
Claim 8
Dependent Claim
70 words
A circuit as claimed in claim 4, wherein each of said first to sixth transistors is a MOS transistor; and wherein said fifth MOS transistor of said input circuit has a gate length L5 and a gate width W5, and said sixth MOS transistor of said input circuit has a gate length L6 and a gate width W6; and wherein L5, W5, L6, and W6 satisfy a relationship of ##EQU12##
Claim 9
Dependent Claim
19 words
A circuit as claimed in claim 1, wherein each of said first to fourth transistors is a MOS transistor.
Claim 10
Dependent Claim
40 words
A circuit as claimed in claim 8, further comprising: a first capacitor connected to a gate and a source of said second MOS transistor; and a second capacitor connected to a gate and a source of said third MOS transistor.
Claim 11
Dependent Claim
79 words
A circuit as claimed in claim 8, wherein said fifth MOS transistor of said input circuit has a gate applied with said first timing signal, and a drain and a source connected to respective gates of said third and fourth MOS transistors; and wherein said sixth MOS transistor of said input circuit has a gate applied with said second timing signal, and a drain and a source connected between a gate and a source of said fourth MOS transistor.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2001-08-17 | 2002-02-16 | 2002-08-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2005-08-17 | 2006-02-16 | 2006-08-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2009-08-17 | 2010-02-16 | 2010-08-18 | $7700.00 | Window Closed / Lapsed |