System and method for automatically calibrating display monitor beam currents

• US 5,978,745 A
• Filed: 01/23/1998
• Issued: 11/02/1999
• Est. Priority Date: 01/23/1998
• Status: Expired due to Term

• Current Assignee: Apple Computer Incorporated (Apple Inc.)
• Original Assignee: Apple Computer Incorporated (Apple Inc.)
• Inventors: Devine, Jesse
• Primary Examiner(s): Barlow, John
• Assistant Examiner(s): Bui, Bryan
• Application Number:
  US09/012,920
• Time in Patent Office: 648 Days
• Field of Search: 702/107, 348/180-182, 348/326, 348/656, 348/658, 376/108
• US Class Current: 702/107
• CPC Class Codes: H04N 17/04 for receivers

Abstract

A system and method for automatically-calibrating display monitor beam currents. A device selects a target beam current within a display monitor. A current sampler measures a present beam current within the display monitor. A beam current controller increases a gain of an amplifier within the monitor by a delta value if the present beam current is less than the target beam current, and decreases the gain of the amplifier by the delta value if the present beam current is greater than the target beam current. A first step in the method selects a target beam current. A second step measures a present beam current generated by an amplifier. A third step increases a gain of the amplifier by a delta value if the present beam current is less than the target beam current. A fourth step decreases the gain of the amplifier by the delta value if the present beam current is greater than the target beam current. A fifth step sets a multiplier to a predetermined value. A sixth step multiplies the delta value by the multiplier. A seventh step reduces the multiplier by a predetermined amount if the present beam current crosses the target beam current.

Claims

1. A method for automatically calibrating display monitor beam currents, comprising the steps of:

selecting a target beam current;

measuring a present beam current generated by an amplifier;

increasing a gain of the amplifier by a first delta value if the present beam current is less than the target beam current;

decreasing the gain of the amplifier by a second delta value if the present beam current is greater than the target beam current; and

repeating the measuring, increasing and decreasing steps until the earlier of the present beam current has approached within a predetermined tolerance of the target beam current or the present beam current has crossed the target beam current a predetermined number of times.

2. The method of claim 1 wherein the increasing step includes the steps of:

setting the first delta value equal to a lesser of a maximum predetermined delta or the target beam current minus the present beam current; and

adding to the gain a greater of a minimum predetermined delta or the first delta value times a multiplier.

3. The method of claim 1 wherein the decreasing step includes the steps of:

setting the second delta value equal to a lesser of a maximum predetermined delta or the present beam current minus the target beam current; and

subtracting from the gain a greater of a minimum predetermined delta or the second delta value times a multiplier.

4. The method of claim 1 further including the steps of:

setting a multiplier to a predetermined value;

multiplying the delta values by the multiplier;

reducing the multiplier by a predetermined amount if the present beam current crosses the target beam current; and

repeating the setting and multiplying steps.

5. The method of claim 4 wherein the setting step includes the step of setting the multiplier to 100%.

6. The method of claim 4 wherein the reducing step includes the step of reducing the multiplier by 25%.

7. The method of claim 1 further including the step of reducing the target beam current by a predetermined amount if the amplifier is to be set to a gain which is greater than or equal to a maximum predetermined gain.

8. The method of claim 7 wherein the reducing step includes the step of reducing the target beam current by 5%.

9. The method of claim 1 further including the step of repeating the method steps until the present beam current is equal to the target beam current.

10. A system for automatically calibrating display monitor beam currents, comprising:

means for selecting a target beam current;

means for measuring a present beam current generated by an amplifier;

means for increasing a gain of the amplifier by a first delta value if the present beam current is less than the target beam current;

means for decreasing the gain of the amplifier by a second delta value if the present beam current is greater than the target beam current; and

means for repeating the means for measuring, increasing and decreasing until the earlier of the present beam current has approached within a predetermined tolerance of the target beam current or the present beam current has crossed the target beam current a predetermined number of times.

11. The system of claim 10 wherein the means for increasing includes:

means for setting the first delta value equal to a lesser of a maximum predetermined delta or the target beam current minus the present beam current; and

means for adding to the gain a greater of a minimum predetermined delta or the first delta value times a multiplier.

12. The system of claim 10 wherein the means for decreasing includes:

means for setting the second delta value equal to a lesser of a maximum predetermined delta or the present beam current minus the target beam current; and

means for subtracting from the gain a greater of a minimum predetermined delta or the second delta value times a multiplier.

13. The system of claim 10 further including:

means for setting a multiplier to a predetermined value;

means for multiplying the delta values by the multiplier;

means for reducing the multiplier by a predetermined amount if the present beam current crosses the target beam current; and

means for repeating the means for setting and multiplying.

14. The system of claim 10 further including means for reducing the target beam current by a predetermined amount if the amplifier is to be set to a gain which is greater than or equal to a maximum predetermined gain.

15. A computer-useable medium embodying computer program code for causing a computer to automatically calibrate display monitor beam currents by performing the steps of:

selecting a target beam current;

measuring a present beam current generated by an amplifier;

increasing a gain of the amplifier by a first delta value if the present beam current is less than the target beam current;

decreasing the gain of the amplifier by a second delta value if the present beam current is greater than the target beam current; and

repeating the measuring, increasing and decreasing steps until the earlier of the present beam current has approached within a predetermined tolerance of the target beam current or the present beam current has crossed the target beam current a predetermined number of times.

16. The computer-useable medium of claim 15 wherein the increasing step further performs the steps of:

setting the first delta value equal to a lesser of a maximum predetermined delta or the target beam current minus the present beam current; and

adding to the gain a greater of a minimum predetermined delta or the first delta value times a multiplier.

17. The computer-useable medium of claim 15 wherein the decreasing step further performs the steps of:

setting the second delta value equal to a lesser of a maximum predetermined delta or the present beam current minus the target beam current; and

subtracting from the gain a greater of a minimum predetermined delta or the second delta value times a multiplier.

18. The computer-useable medium of claim 15 further performing the steps of:

setting a multiplier to a predetermined value;

multiplying the delta values by the multiplier;

reducing the multiplier by a predetermined amount if the present beam current crosses the target beam current; and

repeating the setting and multiplying steps.

19. The computer-useable medium of claim 15 further performing the step of reducing the target beam current by a predetermined amount if the amplifier is to be set to a gain which is greater than or equal to a maximum predetermined gain.

20. A method for automatically calibrating display monitor beam currents, comprising the steps of:

a) selecting a target beam current;

b) setting a multiplier to an initial value of 1.0;

c) measuring a present beam current generated by an amplifier having a gain;

d) if the present beam current is less than the target beam current then setting a delta value to a lesser of a maximum predetermined delta or the target beam current minus the present beam current, and increasing the gain of the amplifier a greater of a minimum of a predetermined delta or a product of the delta value multiplied by said multiplier;

e) if the present beam current is greater than the target beam current then setting the delta value to a lesser of a maximum predetermined delta or the present beam current minus the target beam current, and decreasing the gain of the amplifier a greater of a minimum of a predetermined delta or a product of the delta value multiplied by said multiplier;

f) if the present beam current crosses the target beam current then reducing the multiplier by a predetermined amount; and

g) repeating steps c through f until the present beam current is within a predetermined tolerance of the target beam current.

21. The method of claim 20 wherein step f includes the step of reducing the multiplier by 25%.

22. The method of claim 20 further including the step of reducing the target beam current by a predetermined amount if the amplifier is to be set to a gain which is greater than or equal to a maximum predetermined gain.

23. The method of claim 22 wherein the reducing step includes the step of reducing the target beam current by 5%.