Patent US5481118A successfully refreshed from Google Patents.
US5481118A
Expired / Lapsed
US
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On-chip light sensor
Assignee: Texas Instruments Inc
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Filing: 1995-01-26
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Granted: 1996-01-02
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Expires: 2015-01-26
Abstract
Abstract A brightness sensing circuit for providing a binary electrical signal for indicating whether incident light exceeds a certain brightness. The circuit's light detector is a photodiode, whose output is amplified by a first current mirror. The circuit has a reference current source, whose output is amplified by a second current mirror. Both currents are delivered to a common node, whose voltage level transitions from low to high when the amplified input current exceeds the amplified reference current. This node is connected to the gate input of a CMOS inverter, which provides a binary output.
Inventors
- 👤 Claude E. Tew
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 15:49
CPC Classifications
H; H03; H03K; H03K17/00; H03K17/51; H03K17/78; H03K17/785
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
112 words
A circuit for providing an electrical signal to indicate when incident light exceeds or falls below a certain level of brightness, comprising: a photodiode for detecting incident light and generating an input current; a first current mirror for receiving and amplifying said input current and delivering the amplified input current to an intermediate node; a current source for providing a reference current; a second current mirror for receiving and amplifying said reference current and for delivering the amplified reference current to said intermediate node; and an inverter for receiving the current from said intermediate node and for changing state at its output when said amplified input current exceeds said amplified reference current.
Claim 2
Dependent Claim
112 words
A circuit for providing an electrical signal to indicate when incident light exceeds or falls below a certain level of brightness, comprising: a photodiode for detecting incident light and generating an input current; a first current mirror for receiving and amplifying said input current and delivering the amplified input current to an intermediate node; a current source for providing a reference current; a second current mirror for receiving and amplifying said reference current and for delivering the amplified reference current to said intermediate node; and an inverter for receiving the current from said intermediate node and for changing state at its output when said amplified input current exceeds said amplified reference current.
Claim 3
Dependent Claim
29 words
The circuit of claim 1, wherein at least one of said current mirrors is comprised of a pair of transistors with a common gate connection to said input current.
Claim 4
Dependent Claim
12 words
The circuit of claim 2, wherein said transistors are field effect transistors.
Claim 5
Dependent Claim
24 words
The circuit of claim 1, wherein said inverter is comprised of a pair of transistors with a common gate connection to said reference current.
Claim 6
Dependent Claim
12 words
The circuit of claim 4, wherein said transistors are field effect transistors.
Claim 7
Dependent Claim
19 words
The circuit of claim 1, wherein said current mirrors and said inverter are comprised of MOS field effect transistors.
Claim 8
Dependent Claim
11 words
The circuit of claim 1, wherein said current source is adjustable.
Claim 9
Dependent Claim
18 words
The circuit of claim 1, wherein said current mirrors and said inverter are fabricated as an integrated circuit.
Claim 10
Dependent Claim
115 words
A monolithic device which includes a deformable mirror and a circuit for indicating the brightness level of light incident on the mirror, comprising: at least one micro-mechanical mirror element on said device; and a shut-off circuit on said monolithic device comprising a photodiode for receiving a portion of said light incident on said monolithic device and providing an input current, a first current mirror for amplifying said input current to an intermediate node, a current source for providing a reference current, a second current mirror for amplifying said reference current to said intermediate node, and an inverter connected to said intermediate node for providing a binary output depending on the voltage at said intermediate node.
Claim 11
Dependent Claim
115 words
A monolithic device which includes a deformable mirror and a circuit for indicating the brightness level of light incident on the mirror, comprising: at least one micro-mechanical mirror element on said device; and a shut-off circuit on said monolithic device comprising a photodiode for receiving a portion of said light incident on said monolithic device and providing an input current, a first current mirror for amplifying said input current to an intermediate node, a current source for providing a reference current, a second current mirror for amplifying said reference current to said intermediate node, and an inverter connected to said intermediate node for providing a binary output depending on the voltage at said intermediate node.
Claim 12
Dependent Claim
22 words
The deformable mirror device of claim 9 wherein said binary output affects the operation of said at least one micro-mechanical mirror element.
Claim 13
Dependent Claim
29 words
The device of claim 9, wherein at least one of said current mirrors is comprised of a pair of transistors with a common gate connection to said input current.
Claim 14
Dependent Claim
12 words
The device of claim 11, wherein said transistors are field effect transistors.
Claim 15
Dependent Claim
24 words
The device of claim 9, wherein said inverter is comprised of a pair of transistors with a common gate connection to said intermediate node.
Claim 16
Dependent Claim
12 words
The device of claim 13, wherein said transistors are field effect transistors.
Claim 17
Dependent Claim
19 words
The device of claim 9, wherein said current mirrors and said inverter are comprised of MOS field effect transistors.
Claim 18
Dependent Claim
11 words
The device of claim 9, wherein said current source is adjustable.
Claim 19
Dependent Claim
17 words
The device of claim 9, further comprising an addressing circuit for addressing each of said mirror elements.
Claim 20
Dependent Claim
19 words
The device of claim 17, wherein said shut-off circuit is fabricated on the same substrate as said addressing circuit.
Claim 21
Dependent Claim
23 words
The deformable mirror device of claim 9 further comprising a light source, wherein said binary output affects the operation of said light source.
Claim 22
Independent Claim
68 words
A method of measuring incident light comprising; generating an input current based on the level of said incident light; amplifying said input current; providing a reference current; outputting a first signal level when the magnitude of said amplified input current exceeds the magnitude of said reference current; and outputting a second signal level when the magnitude of said reference current exceeds the magnitude of said amplified input current.
Claim 23
Independent Claim
68 words
A method of measuring incident light comprising; generating an input current based on the level of said incident light; amplifying said input current; providing a reference current; outputting a first signal level when the magnitude of said amplified input current exceeds the magnitude of said reference current; and outputting a second signal level when the magnitude of said reference current exceeds the magnitude of said amplified input current.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1999-01-01 | 1999-07-03 | 2000-01-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2003-01-01 | 2003-07-03 | 2004-01-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2007-01-01 | 2007-07-03 | 2008-01-02 | $7700.00 | Window Closed / Lapsed |