US5956004A
Expired / Lapsed
US
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Controlling pixel brightness in a field emission display using circuits for sampling and discharging
Assignee: Micron Technology Inc
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Filing: 1996-01-09
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Granted: 1999-09-21
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Expires: 2016-01-09
Abstract
Abstract A flat panel display, such as a Field Emission Display ("FED"), is disclosed having a gray scale generator. Input into the display, initially, is an analog signal having an amplitude. The gray scale generator includes a converter for converting the analog input signal to a sawtooth output signal having a height and width. Further, the width of the sawtooth output signal is responsive to the analog input signal's amplitude.
Inventors
- 👤 Glen E. Hush
- 👤 Thomas W. Voshell
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 17:56
CPC Classifications
G; G09; G09G; G09G3/00; G09G3/20; G09G3/22; H; H01; H01J; H01J31/00; H01J31/08; H01J31/10; H01J31/12; H01J31/123; H01J31/125; H01J31/127; G09G2300/00; G09G2300/08; G09G2310/00; G09G2310/02; G09G2310/0243; G09G2310/0248; G09G2310/0259; G09G2310/06; G09G2310/066; G09G2320/00; G09G2320/06; G09G2320/0606; G09G2320/0626; G09G2320/066; G09G3/2007; G09G3/2011; G09G3/2014; H01J2201/00; H01J2201/30; H01J2201/319; H01J2329/00
Claims Analysis
Total Claims: 32
Claim 1
Independent Claim
286 words
A field emission display having a pixel whose brightness varies in response to an analog pixel intensity voltage corresponding to that pixel, comprising: a) a pixel including at least one field emitter tip; b) an analog input for receiving the analog pixel intensity voltage for the pixel; c) a capacitance; d) a sampling switch connected between the analog input and the capacitance, wherein the switch periodically alternates between an on state and an off state so that, when the input switch is in its on state, the switch connects the analog pixel intensity voltage to the capacitance so that the capacitance charges up to a voltage proportional to a current sample of the analog pixel intensity voltage; e) a discharge circuit, connected across the capacitance, for discharging the capacitance at a controlled rate while the sampling switch is in its off state so as to produce across the capacitance, each time the sampling switch switches from its on state to its off state, a progressively declining sawtooth voltage pulse having a peak amplitude and a pulse width both proportional to the current sample of the analog pixel intensity voltage, wherein the periodic alternation of the sampling switch produces periodic sawtooth voltage pulses across the capacitance; f) an emitter control circuit having a control input and having an output connected to the at least one emitter tip, wherein the emitter control circuit conducts to the at least one emitter tip an electrical current whose value is proportional to a signal received at the control input; and g) a driver circuit, connected between the capacitor and the control input, for applying to the control input an electrical signal responsive to the periodic sawtooth voltage pulses across the capacitance.
Claim 2
Dependent Claim
286 words
A field emission display having a pixel whose brightness varies in response to an analog pixel intensity voltage corresponding to that pixel, comprising: a) a pixel including at least one field emitter tip; b) an analog input for receiving the analog pixel intensity voltage for the pixel; c) a capacitance; d) a sampling switch connected between the analog input and the capacitance, wherein the switch periodically alternates between an on state and an off state so that, when the input switch is in its on state, the switch connects the analog pixel intensity voltage to the capacitance so that the capacitance charges up to a voltage proportional to a current sample of the analog pixel intensity voltage; e) a discharge circuit, connected across the capacitance, for discharging the capacitance at a controlled rate while the sampling switch is in its off state so as to produce across the capacitance, each time the sampling switch switches from its on state to its off state, a progressively declining sawtooth voltage pulse having a peak amplitude and a pulse width both proportional to the current sample of the analog pixel intensity voltage, wherein the periodic alternation of the sampling switch produces periodic sawtooth voltage pulses across the capacitance; f) an emitter control circuit having a control input and having an output connected to the at least one emitter tip, wherein the emitter control circuit conducts to the at least one emitter tip an electrical current whose value is proportional to a signal received at the control input; and g) a driver circuit, connected between the capacitor and the control input, for applying to the control input an electrical signal responsive to the periodic sawtooth voltage pulses across the capacitance.
Claim 3
Dependent Claim
17 words
A field emission display according to claim 1, wherein the discharge circuit is a constant current source.
Claim 4
Dependent Claim
55 words
A field emission display according to claim 1, wherein the emitter control circuit comprises a transistor having a channel and a gate, wherein the channel is connected between the at least one emitter tip and a source of electrical current, and wherein the gate is connected to the control input of the emitter control circuit.
Claim 5
Dependent Claim
30 words
A field emission display according to claim 3, wherein the emitter control circuit further comprises: a resistor connected between the channel of the transistor and the source of electrical current.
Claim 6
Dependent Claim
19 words
A field emission display according to claim 1, wherein the capacitance consists essentially of parasitic capacitance of the display.
Claim 7
Dependent Claim
113 words
A field emission display according to claim 1, wherein the driver circuit comprises: a voltage comparator circuit, connected between the capacitance and the control input of the emitter control circuit, for comparing the sawtooth voltage across the capacitance to a threshold voltage so as to provide to the control input a rectangular pulse signal which alternates between first and second distinct amplitudes, wherein the rectangular pulse signal has the first amplitude when the sawtooth voltage is above the threshold voltage and has the second amplitude when the sawtooth voltage is below the threshold voltage, so that the rectangular pulse signal has a pulse width determined by the pulse width of the sawtooth voltage.
Claim 8
Dependent Claim
31 words
A field emission display according to claim 1, wherein the driver circuit consists essentially of an electrical conductor directly connecting the capacitance to the control input of the emitter control circuit.
Claim 9
Independent Claim
240 words
A method of controlling the electrical current flow to the field emitter tips of a pixel of a field emission display in response to an analog pixel intensity voltage corresponding to that pixel, comprising the steps of: providing a pixel including at least one field emitter tip and a capacitance; receiving an analog pixel intensity voltage for the pixel; conducting to said at least one emitter tip of the pixel an electrical current proportional to a control signal received at a control input; at periodic time intervals, alternately connecting and disconnecting the analog pixel intensity voltage to the capacitance so that, during the time intervals when the analog pixel intensity voltage is connected to the capacitance, the capacitance charges up to a voltage proportional to a current sample of the analog pixel intensity voltage; discharging the capacitance at a controlled rate during the time intervals when the analog pixel intensity voltage is disconnected from the capacitance so as to produce across the capacitance, each time the analog pixel intensity voltage is disconnected from the capacitance, a progressively declining sawtooth voltage pulse having a peak amplitude and a pulse width both proportional to the current sample of the analog pixel intensity voltage, wherein said periodic connecting and disconnecting of the analog pixel intensity voltage produces periodic sawtooth voltage pulses across the capacitance; and applying to the control input an electrical signal responsive to the periodic sawtooth voltage pulses across the capacitance.
Claim 10
Independent Claim
240 words
A method of controlling the electrical current flow to the field emitter tips of a pixel of a field emission display in response to an analog pixel intensity voltage corresponding to that pixel, comprising the steps of: providing a pixel including at least one field emitter tip and a capacitance; receiving an analog pixel intensity voltage for the pixel; conducting to said at least one emitter tip of the pixel an electrical current proportional to a control signal received at a control input; at periodic time intervals, alternately connecting and disconnecting the analog pixel intensity voltage to the capacitance so that, during the time intervals when the analog pixel intensity voltage is connected to the capacitance, the capacitance charges up to a voltage proportional to a current sample of the analog pixel intensity voltage; discharging the capacitance at a controlled rate during the time intervals when the analog pixel intensity voltage is disconnected from the capacitance so as to produce across the capacitance, each time the analog pixel intensity voltage is disconnected from the capacitance, a progressively declining sawtooth voltage pulse having a peak amplitude and a pulse width both proportional to the current sample of the analog pixel intensity voltage, wherein said periodic connecting and disconnecting of the analog pixel intensity voltage produces periodic sawtooth voltage pulses across the capacitance; and applying to the control input an electrical signal responsive to the periodic sawtooth voltage pulses across the capacitance.
Claim 11
Dependent Claim
29 words
A method according to claim 8, wherein the step of applying an electrical signal to the control input consists essentially of directly connecting the capacitance to the control input.
Claim 12
Dependent Claim
121 words
A method according to claim 8, wherein the step of applying an electrical signal to the control input comprises the steps of: receiving said sawtooth voltage from the capacitance; comparing the amplitude of the sawtooth voltage received from the capacitance to a threshold voltage so as to produce a rectangular pulse signal which alternates between first and second distinct amplitudes, wherein the rectangular pulse signal has the first amplitude when the sawtooth voltage is above the threshold voltage and has the second amplitude when the sawtooth voltage is below the threshold voltage, so that the rectangular pulse signal has a pulse width determined by the pulse width of the sawtooth voltage; and applying the rectangular pulse signal to the control input.
Claim 13
Dependent Claim
26 words
A method according to claim 8, wherein the step of discharging the capacitance at a controlled rate comprises conducting a constant electrical current from the capacitance.
Claim 14
Dependent Claim
64 words
A method according to claim 8, wherein the step of conducting an electrical current to said at least one emitter tip comprises the steps of: providing a source of electrical current; providing a transistor having a channel and a gate; connecting the channel between said at least one emitter tip and the source of electrical current; and connecting the gate to the control input.
Claim 15
Dependent Claim
41 words
A method according to claim 12, wherein the step of conducting an electrical current to said at least one emitter tip further comprises the step of: connecting a resistor between the channel of the transistor and the source of electrical current.
Claim 16
Dependent Claim
25 words
A method according to claim 8, wherein the capacitance provided in the step of providing a pixel consists essentially of parasitic capacitance within the display.
Claim 17
Dependent Claim
230 words
A field emission display having a pixel whose brightness varies in response to an analog pixel intensity voltage corresponding to that pixel, comprising: a pixel including at least one field emitter tip; an analog input for receiving the analog pixel intensity voltage for the pixel; a capacitance; a sampling switch connected between the analog input and the capacitance, wherein the switch periodically alternates between an on state and an off state so that, when the input switch is in its on state, the switch connects the analog pixel intensity voltage to the capacitance so that the capacitance charges up to a voltage proportional to a current sample of the analog pixel intensity voltage; a discharge circuit, connected across the capacitance, for discharging the capacitance at a controlled rate while the sampling circuit is in its off state so as to produce across the capacitance, each time the sampling switch switches from its on state to its off state, a progressively declining sawtooth voltage pulse having a peak amplitude and a pulse duration both proportional to the current sample of the analog pixel intensity voltage, wherein the periodic alternation of the sampling switch produces periodic sawtooth voltage pulses across the capacitance; and an emitter control circuit for conducting an electrical current to the at least one field emitter tip of the pixel only during the duration of each sawtooth voltage pulse.
Claim 18
Dependent Claim
230 words
A field emission display having a pixel whose brightness varies in response to an analog pixel intensity voltage corresponding to that pixel, comprising: a pixel including at least one field emitter tip; an analog input for receiving the analog pixel intensity voltage for the pixel; a capacitance; a sampling switch connected between the analog input and the capacitance, wherein the switch periodically alternates between an on state and an off state so that, when the input switch is in its on state, the switch connects the analog pixel intensity voltage to the capacitance so that the capacitance charges up to a voltage proportional to a current sample of the analog pixel intensity voltage; a discharge circuit, connected across the capacitance, for discharging the capacitance at a controlled rate while the sampling circuit is in its off state so as to produce across the capacitance, each time the sampling switch switches from its on state to its off state, a progressively declining sawtooth voltage pulse having a peak amplitude and a pulse duration both proportional to the current sample of the analog pixel intensity voltage, wherein the periodic alternation of the sampling switch produces periodic sawtooth voltage pulses across the capacitance; and an emitter control circuit for conducting an electrical current to the at least one field emitter tip of the pixel only during the duration of each sawtooth voltage pulse.
Claim 19
Dependent Claim
17 words
A field emission display according to claim 15, wherein the discharge circuit is a constant current source.
Claim 20
Dependent Claim
58 words
A field emission display according to claim 15, wherein: the emitter control circuit comprises a control input; the emitter control circuit conducts said electrical current to the at least one field emitter tip in response to an electrical signal received at the control input; and the control input of the emitter control circuit is connected to the capacitance.
Claim 21
Dependent Claim
55 words
A field emission display according to claim 17, wherein the emitter control circuit comprises a transistor having a channel and a gate, wherein the channel is connected between the at least one emitter tip and a source of electrical current, and wherein the gate is connected to the control input of the emitter control circuit.
Claim 22
Dependent Claim
30 words
A field emission display according to claim 18, wherein the emitter control circuit further comprises: a resistor connected between the channel of the transistor and the source of electrical current.
Claim 23
Dependent Claim
115 words
A field emission display according to claim 17, further comprising: a voltage comparator circuit, connected between the capacitance and the control input of the emitter control circuit, for comparing the sawtooth voltage across the capacitance to a threshold voltage so as to provide to the control input of the emitter control circuit a rectangular pulse signal which alternates between first and second distinct amplitudes, wherein the rectangular pulse signal has the first amplitude when the sawtooth voltage is above the threshold voltage and has the second amplitude when the sawtooth voltage is below the threshold voltage, so that the rectangular pulse signal has a pulse width determined by the pulse width of the sawtooth voltage.
Claim 24
Dependent Claim
19 words
A field emission display according to claim 15, wherein the capacitance consists essentially of parasitic capacitance of the display.
Claim 25
Independent Claim
216 words
A method of providing to the field emitter tips of a pixel of a field emission display a current flow responsive to an analog pixel intensity voltage corresponding to that pixel, comprising the steps of: providing a pixel including at least one field emitter tip and a capacitance; receiving an analog pixel intensity voltage for the pixel; at periodic time intervals, alternately connecting and disconnecting the analog pixel intensity voltage to the capacitance so that, during the time intervals when the analog pixel intensity voltage is connected to the capacitance, the capacitance charges up to a voltage proportional to a current sample of the analog pixel intensity voltage; discharging the capacitance at a controlled rate during time intervals when the analog pixel intensity voltage is disconnected from the capacitance so as to produce across the capacitance, each time the analog pixel intensity voltage is disconnected from the capacitance, a progressively declining sawtooth voltage pulse having a peak amplitude and pulse duration proportional to the current sample of the analog pixel intensity voltage, wherein said periodic connecting and disconnecting of the analog pixel intensity voltage produces periodic sawtooth voltage pulses across the capacitance; and conducting an electrical current to said at least one emitter tip of the pixel only during the duration of each sawtooth voltage pulse.
Claim 26
Independent Claim
216 words
A method of providing to the field emitter tips of a pixel of a field emission display a current flow responsive to an analog pixel intensity voltage corresponding to that pixel, comprising the steps of: providing a pixel including at least one field emitter tip and a capacitance; receiving an analog pixel intensity voltage for the pixel; at periodic time intervals, alternately connecting and disconnecting the analog pixel intensity voltage to the capacitance so that, during the time intervals when the analog pixel intensity voltage is connected to the capacitance, the capacitance charges up to a voltage proportional to a current sample of the analog pixel intensity voltage; discharging the capacitance at a controlled rate during time intervals when the analog pixel intensity voltage is disconnected from the capacitance so as to produce across the capacitance, each time the analog pixel intensity voltage is disconnected from the capacitance, a progressively declining sawtooth voltage pulse having a peak amplitude and pulse duration proportional to the current sample of the analog pixel intensity voltage, wherein said periodic connecting and disconnecting of the analog pixel intensity voltage produces periodic sawtooth voltage pulses across the capacitance; and conducting an electrical current to said at least one emitter tip of the pixel only during the duration of each sawtooth voltage pulse.
Claim 27
Dependent Claim
26 words
A method according to claim 22, wherein the step of discharging the capacitance at a controlled rate comprises conducting a constant electrical current from the capacitance.
Claim 28
Dependent Claim
59 words
A method according to claim 22, wherein the step of conducting an electrical current to said at least one emitter tip of the pixel comprises the steps of: conducting said electrical current to said at least one field emitter tip in response to an electrical signal received at a control input; and connecting the capacitance to the control input.
Claim 29
Dependent Claim
68 words
A method according to claim 24, wherein the step of conducting said electrical current in response to an electrical signal received at a control input comprises the steps of: providing a source of electrical current; providing a transistor having a channel and a gate; connecting the channel between said at least one emitter tip and the source of electrical current; and connecting the gate to the control input.
Claim 30
Dependent Claim
45 words
A method according to claim 25, wherein the step of conducting said electrical current in response to an electrical signal received at a control input further comprises the step of: connecting a resistor between the channel of the transistor and the source of electrical current.
Claim 31
Dependent Claim
117 words
A method according to claim 24, wherein the step of connecting the capacitance to the control input comprises the steps of: receiving said sawtooth voltage from the capacitance; comparing the sawtooth voltage received from the capacitance to a threshold voltage so as to produce a rectangular pulse signal which alternates between first and second distinct amplitudes, wherein the rectangular pulse signal has the first amplitude when the sawtooth voltage is above the threshold voltage and has the second amplitude when the sawtooth voltage is below the threshold voltage, so that the rectangular pulse signal has a pulse width determined by the pulse width of the sawtooth voltage; and applying the rectangular pulse signal to the control input.
Claim 32
Dependent Claim
25 words
A method according to claim 22, wherein the capacitance provided in the step of providing a pixel consists essentially of parasitic capacitance within the display.
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| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 2002-09-20 | 2003-03-22 | 2003-09-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2006-09-20 | 2007-03-22 | 2007-09-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2010-09-20 | 2011-03-22 | 2011-09-21 | $7700.00 | Window Closed / Lapsed |