Abstract: A current controlled field emission display includes a controller that provides a pair of pulsed clocking signals that allows current to flow from ground potential to an emitter in the field emission display during each clocking signal pulse. The number of electrons, and thus the intensity of the light will depend upon the number N of clocking signal pulses during an activation interval. In one embodiment, each of the pulsed signals includes a number N of pulses that corresponds to a desired intensity of pixels. The pulsed signals are formed by gating a clock signal in response to digital data applied to the display such that the transfer of electrons is controlled directly by the digital data. In another embodiment, the pulsed signals are produced by comparing a decoded image signal to counts from a high speed counter.

Abstract: A current controlled field emission display includes a controller that provides a pair of pulsed clocking signals that allows current to flow from ground potential to an emitter in the field emission display during each clocking signal pulse. The number of electrons, and thus the intensity of the light will depend upon the number N of clocking signal pulses during an activation interval. In one embodiment, each of the pulsed signals includes a number N of pulses that corresponds to a desired intensity of pixels. The pulsed signals are formed by gating a clock signal in response to digital data applied to the display such that the transfer of electrons is controlled directly by the digital data. In another embodiment, the pulsed signals are produced by comparing a decoded image signal to counts from a high speed counter.

Abstract: A method and a control circuit for controlling a field emission display to reduce emission to grid during turn on and turn off are provided. In an illustrative embodiment, the control circuit includes a threshold detector that receives an input signal proportional to an anode voltage (VAnode) for the display and produces a high or low output signal dependent on the level of VAnode. An output low corresponding to a high voltage at the display screen enables a gate element of a pass transistor that controls current flow to the grid. Alternately, an output high corresponding to a low voltage at the display screen enables a pull down transistor that controls discharge of the grid to ground. The control circuit can also include a fault detection circuit for detecting a sharp decrease in the anode voltage and discharging the grid.

Abstract: A field emission display includes an array of emitter sites, a grid for controlling electron emission from the emitter sites, and a display screen. The field emission display also includes a control circuit for controlling the grid for preventing emission to grid. The control circuit includes a high impedance grid bias path, and a low impedance grid bias path. In addition, the control circuit includes a sensing-switching circuit for sensing an anode voltage at the display screen, and switching from the high impedance to the low impedance grid bias path upon detection of a threshold anode voltage. An alternate embodiment control circuit is configured to provide a programmable delay during enabling of the grid to insure that the display screen reaches the threshold voltage prior to electron emission. An alternate embodiment field emission display includes a focus ring that is controlled to prevent emission to grid.

Abstract: Method and apparatus for ensuring that, in a portable, battery-powered communication package incorporating at least two communication devices, such as a combination cellular telephone and a pager, sufficient power is provided for extended operation of the communication device having the lowest continuous power consumption requirements when the device having a higher continuous power consumption rate has consumed a selected portion of the total power initially available to the combined devices. In the case of the aforestated exemplary device, cellular telephone function is disabled when a selected portion of the total power initially available is consumed. A first embodiment of the invention is implemented with a single electrochemical battery. The first embodiment of the invention may include a headroom-limited flyback power supply which powers the high-power consumption device. When headroom drops below a minimum set by a series-coupled diode string, power is cut off to the high-power-consumption device.

Abstract: A field emission display includes electrostatic discharge protection circuits coupled to an emitter substrate and an extraction grid. In the preferred embodiment, the electrostatic discharge circuit includes diodes reverse biased between grid sections and a first reference potential or between row lines and a second reference potential. The diodes provide a current path to discharge static voltage and thereby prevent a high voltage differential from being maintained between the emitter sets and the extraction grids. The diodes thereby prevent the emitter sets from emitting electrons at a high rate that may damage or destroy the emitter sets. In one embodiment, the diodes are coupled directly between the grid sections and the row lines. In one embodiment, the diodes are formed in an insulative layer carrying the grid sections. In another embodiment, the diodes are integrated into the emitter substrate.

Abstract: A field emission display device includes a baseplate having a set of field-induced electron emitters for each pixel in a display. Each set includes a plurality of emitters each carried by a supporting substrate and disposed within a respective aperture in an insulating layer deposited on the surface of the substrate. A conductive layer is deposited on the insulating layer peripherally about the apertures. A plurality of emitter conductors are each operatively coupled to the emitters of one of the sets of emitters. A conductive voltage applied to the conductive layer and a source voltage applied to one of the emitter conductors causes the emitters coupled to the emitter conductor to each emit an electron emission. The display device also includes a faceplate having a transparent viewing layer positioned in a parallel spaced-apart relationship with the baseplate. An anode is deposited on a planar surface of the viewing layer opposite the sets of emitters.

Abstract: A field emission display includes an array of emitter sites, a grid for controlling electron emission from the emitter sites, and a display screen. The field emission display also includes a control circuit for controlling the grid for preventing emission to grid. The control circuit includes a high impedance grid bias path, and a low impedance grid bias path. In addition, the control circuit includes a sensing-switching circuit for sensing an anode voltage at the display screen, and switching from the high impedance to the low impedance grid bias path upon detection of a threshold anode voltage. An alternate embodiment control circuit is configured to provide a programmable delay during enabling of the grid to insure that the display screen reaches the threshold voltage prior to electron emission. An alternate embodiment field emission display includes a focus ring that is controlled to prevent emission to grid.

Abstract: Method and apparatus for ensuring that, in a portable, battery-powered communication package incorporating at least two communication devices, such as a combination cellular telephone and a pager, sufficient power is provided for extended operation of the communication device having the lowest continuous power consumption requirements when the device having a higher continuous power consumption rate has consumed a selected portion of the total power initially available to the combined devices. In the case of the aforestated exemplary device, cellular telephone function is disabled when a selected portion of the total power initially available is consumed. A first embodiment of the invention is implemented with a single electrochemical battery. The first embodiment of the invention may include a headroom-limited flyback power supply which powers the high-power consumption device. When headroom drops below a minimum set by a series-coupled diode string, power is cut off to the high-power-consumption device.

Abstract: A field emission display includes an array of emitter sites, a grid for controlling electron emission from the emitter sites, and a display screen. The field emission display also includes a control circuit for controlling the grid for preventing emission to grid. The control circuit includes a high impedance grid bias path, and a low impedance grid bias path. In addition, the control circuit includes a sensing-switching circuit for sensing an anode voltage at the display screen, and switching from the high impedance to the low impedance grid bias path upon detection of a threshold anode voltage. An alternate embodiment control circuit is configured to provide a programmable delay during enabling of the grid to insure that the display screen reaches the threshold voltage prior to electron emission. An alternate embodiment field emission display includes a focus ring that is controlled to prevent emission to grid.

Abstract: A field emission display and method of fabricating same in which the emitters are fabricated on a polysilicon layer that is deposited on top of a relatively thick oxide insulating layer. The polysilicon layer extends into gaps formed in the insulating layer to make contact with a conductive layer deposited on a nonconductive substrate. Because of the spacing between the substrate and the polysilicon layer provided by the insulating layer, the conductive layer can extend beneath the emitters to periodically make contact with the polysilicon layer through spaced-apart gaps in the insulating layer. A thin oxide insulating layer is formed over the polysilicon layer, and a second polysilicon layer is then deposited over the thin oxide layer to form an extraction grid.

Abstract: A field emission display has electron emitters that are current-limited by implanting in a silicon layer only enough ions to produce a desired current, and then forming emitters from the silicon layer by isotropic etching.

Abstract: A transmission line tap for a field emission display includes a driving circuit formed from a charging and clearing circuit and a storage circuit. In one embodiment, the charging and clearing circuit is a single transistor coupled between a supply voltage and the storage circuit. The storage circuit is a single storage capacitor coupled between the transistor and the reference potential. In another embodiment, the charging and clearing circuit is formed from three transistors and an intermediate capacitor, and the storage circuit is formed from a storage capacitor and an output buffer. In either embodiment, pulses of an input voltage selectively charge the storage capacitor to a fixed voltage. The driving circuit then drives a column line of an emitter substrate in response to the storage capacitor. In the first embodiment, the storage capacitor is cleared by pulsing the supply voltage.

Abstract: A method and a control circuit for controlling a field emission display to reduce emission to grid during turn on and turn off are provided. In an illustrative embodiment, the control circuit includes a threshold detector that receives an input signal proportional to an anode voltage (V.sub.Anode) for the display and produces a high or low output signal dependent on the level of V.sub.Anode. An output low corresponding to a high voltage at the display screen enables a gate element of a pass transistor that controls current flow to the grid. Alternately, an output high corresponding to a low voltage at the display screen enables a pull down transistor that controls discharge of the grid to ground. The control circuit can also include a fault detection circuit for detecting a sharp decrease in the anode voltage and discharging the grid.

Abstract: A transmission line tap for a field emission display includes a driving circuit formed from a charging and clearing circuit and a storage circuit. In one embodiment, the charging and clearing circuit is a single transistor coupled between a supply voltage and the storage circuit. The storage circuit is a single storage capacitor coupled between the transistor and the reference potential. In another embodiment, the charging and clearing circuit is formed from three transistors and an intermediate capacitor, and the storage circuit is formed from a storage capacitor and an output buffer. In either embodiment, pulses of an input voltage selectively charge the storage capacitor to a fixed voltage. The driving circuit then drives a column line of an emitter substrate in response to the storage capacitor. In the first embodiment, the storage capacitor is cleared by pulsing the supply voltage.

Abstract: A system for sampling an analog or digital data signal at a relatively high rate utilizing relatively slow circuitry. The system includes several sample and hold circuits, each of which receive the data signal. The sample and hold circuits are clocked by respective clock signals that are at the same frequency but equally phased apart from each other. Thus, the sample and hold circuits take samples of the data signal at times that are equally spaced apart from each other. Each of the sample and hold circuits is connected to a series of shift registers that are clocked at the same frequency as the clock used to clock the sample and hold circuit to which they are connected. The shift registers operate to sequentially store samples obtained by their respective sample and hold circuit. The output of the shift registers may be applied to the column drivers of a conventional matrix display.

Abstract: An apparatus is provided for modulating a conductive element in an FED device from a first level to a second level in which the charge on the display is conserved. In one embodiment, the apparatus comprises an analog modulating circuit, a switching circuit, and a switch. The analog modulating circuit receives a feedback signal responsive to an actual row-column voltage difference and a target signal responsive to a desired row-column voltage difference and generates an output signal responsive to the feedback signal and the target signal. The switching circuit generates a switching signal responsive to the feedback signal, the target signal, and a bias signal. The switch connects a reference voltage to the output generated by the analog modulating circuit in response to the switching signal.

Abstract: Aligned gate structures for field emitter display devices are formed by overlaying a substrate, having at least one emitter tip thereon, successively with an insulating layer, a conductive layer, and a photoresist layer. The photoresist layer is then exposed to create fixed and unfixed regions. The unfixed regions are developed and etched to remove the conductive layer under the unfixed regions. The insulating layer is then etched to expose the emitter tips and the photoresist layer removed.

Abstract: A field emission display includes electrostatic discharge protection circuits coupled to an emitter substrate and an extraction grid. In the preferred embodiment, the electrostatic discharge circuit includes diodes reverse biased between grid sections and a first reference potential or between row lines and a second reference potential. The diodes provide a current path to discharge static voltage and thereby prevent a high voltage differential from being maintained between the emitter sets and the extraction grids. The diodes thereby prevent the emitter sets from emitting electrons at a high rate that may damage or destroy the emitter sets. In one embodiment, the diodes are coupled directly between the grid sections and the row lines. In one embodiment, the diodes are formed in an insulative layer carrying the grid sections. In another embodiment, the diodes are integrated into the emitter substrate.

Abstract: A field emission display includes a discrete storage capacitor coupled between a column line and a reference potential. The display also includes a discharge circuit coupled between a transmission line tap and the storage capacitor. The discharge circuit receives an image signal from the transmission line and transfers charge from the transmission line to the storage capacitor. In one embodiment, the discharge circuit includes a pair of opposed zener diodes. In response to a brief negative-going input pulse on the transmission line, the capacitor is discharged through the diodes. Then, the diodes recover and capacitor and column line are isolated from the tap. A selected line of an extraction grid is then activated to extract electrons from an emitter set coupled to the column line. The voltage differential between the extraction grid and the emitter set extracts electrons from the emitter set that are replaced by the capacitor.