1. An image forming apparatus comprising:
a light source that outputs a plurality of laser beams;
a splitting unit that splits each of the laser beams into a first laser beam that is used for light intensity control and a second laser beam that is used to scan a photosensitive element;
a light-intensity-signal output unit that outputs for each of the first laser beams a corresponding light intensity signal that is indicative of the light intensity thereof; and
a control unit that adjusts the light intensity of each of the laser beams to a target light intensity by referring to the light intensity signal, wherein
the control unit includes
a common-control-value calculating unit that calculates a common control value that is used for light intensity control of every laser beam;
a correction-value calculating unit that calculates a correction value for each of the laser beams, wherein the correction value is used to correct the common control value; and
a threshold calculating unit that calculates a threshold of each of the laser beams, wherein the threshold corresponds to a value of current at which oscillation of the laser beam starts,
the correction-value calculating unit calculates the correction value so that, when the laser beam is driven by a first control value, the light intensity of the laser beam is equal to the target light intensity, wherein the first control value is a value calculated by correcting the common control value using the correction value to obtain a corrected control value and adding the threshold to the corrected control value, and
the threshold calculating unit calculates the threshold so that, when the laser beam is driven by a second control value, the light intensity of the laser beam is equal to the target light intensity multiplied by a predetermined factor, wherein the second control value is a value calculated by correcting the common control value using the correction value to obtain the corrected control value, multiplying the corrected control value by the predetermined factor to obtain a multiplied control value, and adding the threshold to the multiplied control value.
2. The image forming apparatus according to claim 1, wherein the common-control-value calculating unit, the correction-value calculating unit, and the threshold calculating unit calculate the common control value, the correction value, and the threshold, respectively using a feedback system.
3. The image forming apparatus according to claim 1, wherein the common-control-value calculating unit calculates the common control value only during a period after an image is formed on an arbitrary recording sheet and before another image is formed on a recording sheet that follows the arbitrary recording sheet.
4. The image forming apparatus according to claim 1, wherein the threshold calculating unit calculates the threshold only during a period after an image is formed on an arbitrary recording sheet and before another image is formed on a recording sheet that follows the arbitrary recording sheet.
5. A light intensity control method performed by an image forming apparatus, wherein the image forming apparatus includes
a light source that outputs a plurality of laser beams;
a splitting unit that splits each of the laser beams into a first laser beam that is used for light intensity control and a second laser beam that is used to scan a photosensitive element; and
a light-intensity-signal output unit that outputs for each of the first laser beams a corresponding light intensity signal that is indicative of the light intensity thereof, the light intensity control method comprising:
calculating, by a common-control-value calculating unit, a common control value that is used for light intensity control of every laser beam;
calculating, by a correction-value calculating unit, a correction value for each of the laser beams, wherein the correction value is used to correct the common control value; and
calculating, by a threshold calculating unit, a threshold of each of the laser beams, wherein the threshold corresponds to a value of current at which oscillation of the laser beam starts, wherein
the correction-value calculating unit calculates, in the calculating, the correction value so that the light intensity of the laser beam is equal to a target light intensity when the laser beam is driven by a first control value, wherein the first control value is calculated by correcting the common control value using the correction value to obtain a corrected control value and adding the threshold to the corrected control value, and
the threshold calculating unit calculates, in the calculating, the threshold so that, when the laser beam is driven by a second control value, the light intensity of the laser beam is equal to the target light intensity multiplied by a predetermined factor, wherein the second control value is a value calculated by correcting the common control value using the correction value to obtain the corrected control value, multiplying the corrected control value by the predetermined factor to obtain a multiplied control value, and adding the threshold to the multiplied control value.
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. A method of sampling a material, the method comprising:
providing a sample collecting element comprising a first sampling compartment and a second sampling compartment;
placing the first sampling compartment in a passage comprising an inlet and an outlet, the first sampling compartment being placed between the inlet and the outlet of the passage;
flowing the material through an entire length of the first sampling compartment, and through the passage from the inlet to the outlet;
sampling substantially the entire cross-sectional flow of the material through the passage by closing a valve in the passage below the first sampling compartment thereby building up a column of material through the first sampling compartment thereby collecting a sample of the material in the first sampling compartment;
shifting the sample collecting element thereby removing the first sampling compartment from the passage;
placing the second sampling compartment in the passage; and
weighing the sample of the material.
2. The method of claim 1, wherein the sample collecting element comprises a disc, and removing the first sampling compartment from the passage comprises shifting the disc through the passage.
3. The method of claim 2, wherein shifting the disc comprises rotating the disc 180\xb0 through the passage.
4. The method of claim 1, wherein removing the first sampling compartment from the passage comprises shifting the first sampling compartment out of the passage.
5. The method of claim 1 wherein the inlet of the passage comprises a source and wherein the outlet of the passage comprises a bulk collection container along a flowpath, wherein the first sampling compartment is disposed in the flowpath between the source and the bulk collection container.
6. The method of claim 5, further comprising reopening the flow of material from the source to the bulk collection container through the second sampling compartment.
7. The method of claim 4, wherein shifting the sample collecting element positions the first sampling compartment and the sample of the material in a removal position wherein the sampled material flows from the first sampling compartment into a sample container.
8. The method of claim 1, wherein shifting the sample collecting element reopens the flow of material in the passage through the second sampling compartment.
9. The method of claim 1, further comprising:
sampling substantially the entire cross-sectional flow of the material through the passage by collecting material in the second sampling compartment;
shifting a sample collecting element thereby removing sampled material from the passage.
10. The method of claim 1, wherein shifting the sample collecting element removes the first sampling compartment out of the passage and places the second sampling compartment in the passage.