摘要:
A dimmable arc lamp assembly comprises a lamp enclosure comprising a chamber enclosing a light-emitting material, first and second electrodes extending into the chamber of the lamp enclosure, and a heating element proximate the chamber configured to heat at least a portion of the lamp enclosure to a temperature greater than the boiling point of the light-emitting material such that the light-emitting material remains in a gaseous state. Because the light-emitting material remains above its boiling point during lamp operation, dimming is not susceptible to control issues that can result from condensation of the light-producing material. Such lamps may be used in various applications such as in flat panel displays.
摘要:
Methods and apparatus are provided for increasing the life of a fluorescent lamp suitable for use as a backlight in an avionics or other liquid crystal display (LCD). The apparatus includes a channel configured confine a vaporous material that produces an ultra-violet light when electrically excited. A layer of light-emitting material is disposed within at least a portion of the channel is responsive to the ultra-violet light to produce the visible light emitted from the lamp. An electrode assembly that electrically excites the vaporous material includes a first post, a second post, a conductive filament suspended between the first post and the second post and having a tail portion extending therebeyond, and a benign insulating material such as glass frit substantially covering the tail portion to prevent radio frequency (RF) emissions from the tail portion of the filament.
摘要:
A dimmable arc lamp assembly comprises a lamp enclosure comprising a chamber enclosing a light-emitting material, first and second electrodes extending into the chamber of the lamp enclosure, and a heating element proximate the chamber configured to heat at least a portion of the lamp enclosure to a temperature greater than the boiling point of the light-emitting material such that the light-emitting material remains in a gaseous state. Because the light-emitting material remains above its boiling point during lamp operation, dimming is not susceptible to control issues that can result from condensation of the light-producing material. Such lamps may be used in various applications such as in flat panel displays.
摘要:
Methods and apparatus are provided for increasing the luminous output of a fluorescent lamp suitable for use as a backlight in an avionics or other liquid crystal display (LCD). The apparatus includes a channel configured confine a vaporous material that produces an ultra-violet light when electrically excited. A layer of light-emitting material disposed within at least a portion of the channel is responsive to the ultra-violet light to produce the visible light emitted from the lamp. To increase the luminous output of the lamp, the surface area of the light-emitting material is increased through the presence of one or more grooves. The grooves may be longitudinal or transverse with respect to the channel.
摘要:
A logarithmic amplifier produces a logarithmic output signal as a function of an input signal. The amplifier comprises a reference signal, first and second function generators, and a low-pass filter. The first function generator produces a periodic exponential waveform from the reference signal based upon a resistor-capacitor time constant, wherein the exponential waveform exponentially increases from a minimum to a maximum in each period. The second function generator produces a pulsed waveform from the exponential waveform, wherein the pulsed waveform comprises a first portion having a first amplitude for a first time period and a second portion having a different amplitude for the remainder of the signal period, and wherein the duration of the first time period is determined in response to the exponential waveform. The low pass filter produces the logarithmic output signal as a function of the pulsed waveform.
摘要:
An infinite impulse response (IIR) filter provides fast response time without significant effects of ringing or overshoot. In a first step, an input signal is received and a preliminary output signal is computed based upon at least the input signal and a prior output signal. The preliminary output signal is compared to the input signal, and if the preliminary output signal and the input signal differ by more than a significant amount, the input signal is provided as the output signal. Otherwise, the preliminary output signal can be provided as the output signal. Such a filter be readily implemented in software or other programmable logic, and may have particular utility in preserving the contrast in a filtered video image represented by discrete digital data within a display system.
摘要:
A driver circuit provides electrical energy from a power source to a fluorescent lamp such as that used in a flat-panel or other liquid crystal display (LCD). The circuit includes a transformer having a primary winding and a secondary winding, with the ends of the secondary winding coupled to the fluorescent lamp. A first switch switchably provides a drive output signal to the transformer based upon a switch input signal. A current control loop adjusts the switch input in response to the current in one of the windings of the transformer, and a luminance control loop adjusts the switch input in response to the brightness of the light. A lamp current frequency control loop adjusts the polarity of the primary winding in response to a signal received from the transformer to thereby adjust the frequency of the lamp drive current applied to the fluorescent lamp.
摘要:
Methods and apparatus are provided for increasing the efficiency of a fluorescent lamp suitable for use as a backlight in a liquid crystal display (LCD). The apparatus includes a light producing cavity/channel that encloses a vaporous material that produces an ultraviolet light when electrically excited. A layer of light-emitting material within the channel produces the visible light emitted from the lamp in response to the ultraviolet light, and a faceplate made up of a substantially transparent material is affixed to the cavity to confine the vaporous material. To increase the efficiency of the lamp, a coating is provided on the faceplate that reflects ultraviolet light and transmits visible light. The coating may be applied on either the internal or external surface of the faceplate.
摘要:
A driver circuit provides electrical energy from a power source to a fluorescent lamp such as that used in a flat-panel or other liquid crystal display (LCD). The circuit includes a transformer having a primary winding and a secondary winding, with the ends of the secondary winding coupled to the fluorescent lamp. A first switch switchably provides a drive output signal to the transformer based upon a switch input signal. A current control loop adjusts the switch input in response to the current in one of the windings of the transformer, and a luminance control loop adjusts the switch input in response to the brightness of the light. A lamp current frequency control loop adjusts the polarity of the primary winding in response to a signal received from the transformer to thereby adjust the frequency of the lamp drive current applied to the fluorescent lamp.
摘要:
An anti-exponential amplifier produces an output signal that is an exponential/anti-logarithmic function of an input signal. The amplifier includes three function generators and a low-pass filter. The first function generator produces a periodic exponential waveform based upon a resistor-capacitor time constant, with the magnitude of the periodic exponential waveform exponentially increasing to a maximum value in each period. A second function generator produces a ramp waveform from the exponential waveform. The ramp waveform has a period and maximum amplitude substantially equal to those of the exponential signal. The third function generator produces a hybrid waveform with a first portion and a second portion, with the duration of the first period determined in response to the ramp waveform. A low pass filter produces the anti-logarithmic output signal as a function of the hybrid waveform. The resulting amplifier could be useful in a brightness or other parameter control for a display.