1. A system for stabilization of electron multiplier anode bias under a dynamic voltage input, comprising:
an electron multiplier having a cathode end receiving an ion flow, an opposite emitter end and an interior surface, the electron multiplier producing an electron output from ions colliding with the interior surface;
a variable power supply having a voltage output coupled to the cathode end and the emitter end of the electron multiplier, the voltage output changing dynamically to adjust the electron output from the electron multiplier;
an anode in proximity to the electron multiplier;
an electrometer coupled to the anode in proximity to the electron multiplier to measure the current generated by the electron output;
a low pass filter circuit coupled between the emitter end to the ground of the electrometer, the low pass filter to attenuate emitter voltage changes; and
a bias circuit coupled to the emitter end to stabilize emitter to anode voltage difference.
2. The system of claim 1, wherein the low pass filter circuit includes a bypass capacitor coupled between the bias resistor and the ground of the electrometer.
3. The system of claim 2, wherein the bypass capacitor value is selected based on channel impedance of the electron multiplier.
4. The system of claim 1, wherein the bias circuit includes:
an input resistor coupled to the emitter of the electron multiplier;
a zener diode coupled to the input resistor and ground; and
a capacitor coupled in parallel to the zener diode.
5. The system of claim 4, wherein the resistor value and capacitor value is selected to minimize loading of the capacitor and voltage drop generated by the current created by the dynamic voltage.
6. The system of claim 1, further comprising an electrometer shield enclosing a part of the electron multiplier, wherein the low pass filter and bias circuit are integrated in the electrometer shield.
7. The system of claim 1, wherein the electron multiplier includes a cylindrical channel body and wherein the interior surface is treated to allow high electron emission.
8. A method of stabilizing voltage output from an ion detector having an electron multiplier with a cathode, an anode, and an emitter between the cathode and the emitter, the method comprising:
receiving an ion stream via the electron multiplier;
producing an electron stream by applying a voltage between the electron multiplier cathode and anode;
dynamically adjusting electron multiplication in the electron multiplier by changing the voltage;
stabilizing the voltage drop between the electron multiplier anode and a common ground of an electrometer via a zener diode;
attenuating noise generated by the zender diode via a low pass filter; and
filtering the emitter voltage to eliminate changes to the emitter voltage caused by the dynamic gain controlling voltage input via a bias circuit.
9. The method of claim 8, further comprising measuring the electron stream by the electrometer.
10. The method of claim 8, wherein the low pass filter circuit includes a bypass capacitor coupled between the bias resistor and the ground.
11. The method of claim 10, wherein the bypass capacitor value is selected based on channel impedance of the electron multiplier.
12. The method of claim 8, wherein the bias circuit includes
an input resistor coupled to the emitter of the electron multiplier;
a zener diode coupled to the input resistor and ground; and
a capacitor coupled in parallel to the zener diode.
13. The method of claim 12, wherein the resistor value and capacitor value is selected to minimize loading of the capacitor and voltage drop generated by the current created by the dynamic voltage.
14. The method of claim 8, further comprising enclosing a part of the electron multiplier via an electrometer shield, wherein the low pass filter and bias circuit are integrated in the electron shield.
15. The method of claim 1, wherein the electron multiplier includes a cylindrical channel body having an interior surface is treated to allow high electron emission via collisions from the ion stream.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. An apparatus for displaying gray scales of a plasma display panel (PDP), by which gray scales are displayed by arranging a plurality of sub-fields having brightness weights in the order of time and the number of sub-fields is determined according to an average signal level (ASL) of video data, the apparatus comprising:
an automatic power controller for detecting an ASL in each field of video data;
first and second memories for storing the video data in even frames and odd frames;
a sub-field generator for mapping the video data output from the automatic power controller according to the number of sub-fields that is determined by the ASL detected by the automatic power controller, generating corresponding gray scale data, and selectively storing the gray scale data in the first and second memories;
an address data generator for generating address data corresponding to the gray scale data output from the sub-field generator and applying the address data to the PDP;
an ASL controller for comparing the number of sub-fields that are determined by the ASL in a current field from the automatic power controller with the number of sub-fields that are determined by the ASL in a previous field from the automatic power controller, and controlling the output number of sub-fields; and
a sustain scan pulse generator for receiving the number of sub-fields that is controlled by and output from the ASL controller, generating corresponding sustain pulses and scan pulses, and applying the sustain pulses and scan pulses to the PDP,
wherein the sub-field generator maps the video data of the current field according to the number of sub-fields that is determined by the ASL of the previous field video data, and stores the video data of the current field in either the first memory or the second memory, and
wherein the ASL controller compares the number of sub-fields corresponding to the ASL of the current field with the number of sub-fields corresponding to the ASL of the previous field, outputs the number of sub-fields corresponding to the ASL of the current field to the sustain scan pulse generator when the number of sub-fields corresponding to the ASL of the previous field is equal to the number of sub-fields corresponding to the ASL of the current field, and outputs the number of sub-fields corresponding to the ASL of the previous field to the sustain scan pulse generator when the number of sub-fields corresponding to the ASL of the previous field is different from the number of sub-fields corresponding to the ASL of the current field.
2. A method for displaying gray scales of a plasma display panel (PDP), by which gray scales are displayed by arranging a plurality of sub-fields having brightness weights in the order of time and the number of sub-fields is determined according to an average signal level (ASL) of video data, the method comprising:
(a) detecting the ASL of the video data of the current field;
(b) mapping the video data of the current field according to the number of sub-fields that is determined by the ASL of the previously detected video data of a previous field, and storing the video data of the current field;
(c) comparing the number of sub-fields that is determined by the ASL of the video data of the current field with the number of sub-fields that is determined by the ASL of the video data of the previous field, and controlling the output number of sub-fields; and
(d) applying the video data of the current field, which are stored in the step (b), to the PDP and generating sustain scan pulses according to the number of sub-fields, which is controlled in the step (c), and applying the sustain scan pulses to the PDP at the same time,
wherein in the step (c), the number of sub-fields that is determined by the ASL of the video data of the current field is output when the number of sub-fields that is determined by the ASL of the video data of the previous field is equal to the number of sub-fields that is determined by the ASL of the video data of the current field,
and the number of sub-fields that is determined by the ASL of the video data of the previous field is output when the number of sub-fields that is determined by the ASL of the video data of the previous field is different from the number of sub-fields that is determined by the ASL of the video data of the current field.