Patent Grant
7480469
The disclosure relates to a system and method for determining an amount of toner mass present on a toner application surface, and the calibration of the system.
Conventional printing devices exist in which a photoreceptor belt is used to provide toner mass to a base medium (e.g., paper). In order to accurately control the amount of toner mass being delivered to the base medium, these devices tend to include systems that determine the amount of toner mass being carried by the photoreceptor belt. These systems tend to be temperamental and sensitive to changes to the photoreceptor belt, and/or other components of the printing device, that occur due to wear. For example, the surface of the photoreceptor belt may degrade over time such that surfaces on the belt become less reflective, less uniform, etc. This may cause light that is directed to the belt (e.g., for the purpose of measuring the amount of toner mass present, etc.) to be “lost” in the system through absorption, scattering, and/or transmission. The loss of light caused by imperfections in the belt, and/or other components of the printing device may require relatively frequent calibration of the device using a relatively intricate and time consuming process.
These and other drawbacks associated with printing devices and systems that determine the amount of toner mass being delivered to a base medium by a printing device exist.
One aspect of the disclosure a system that determines an amount of toner mass present on a toner application surface. In one embodiment, the system comprises a specular reflection sensor, a diffuse reflection sensor, an output combination module, and a mass determination module. The specular reflection sensor (i) is arranged to receive electromagnetic radiation that has been specularly reflected by the toner application surface and (ii) is configured to generate a specular reflection output representative of one or more of the properties of the electromagnetic radiation received by the specular reflection sensor. The diffuse reflection sensor (i) is arranged to receive electromagnetic radiation that has been diffusely reflected by the toner application surface and (ii) is configured to generate a diffuse reflection output representative of one or more of the properties of the electromagnetic radiation received by the diffuse reflection sensor. The output combination module creates a combined output by combining the specular reflection output and the diffuse reflection output. The mass determination module determines an amount of toner mass present on the toner application surface based on the combined output.
Another aspect of the invention a method of determining an amount of toner mass present on a toner application surface. In one embodiment, the method comprises receiving electromagnetic radiation that has been specularly reflected by the toner application surface; generating a specular reflection output representative of one or more of the properties of the received electromagnetic radiation that has been specularly reflected by the toner application surface; receiving electromagnetic radiation that has been diffusely reflected by the toner application surface; generating a diffuse reflection output representative of one or more of the properties of the received electromagnetic radiation that has been diffusely reflected by the toner application surface; combining the specular reflection output and the diffuse reflection output to create a combined output; and determining an amount of toner mass present on the toner application surface based on the combined output.
Another aspect of the disclosure relates to a method of calibrating a system configured to determine an amount of toner mass present on a toner application surface. In one embodiment, the method comprises directing electromagnetic radiation the toner application surface while the toner application surface carries a known amount of toner mass such that a portion of the electromagnetic radiation is specularly reflected by the toner application surface and a portion of the electromagnetic radiation is diffusely reflected by the toner application surface, wherein one or more properties of the portion of electromagnetic radiation that is specularly reflected by the toner application surface and the portion of electromagnetic radiation that is diffusely reflected by the toner application surface vary as a function of (i) the amount of toner present on the toner application surface and (ii) noise caused by light loss in the system being calibrated; receiving, with a specular reflection sensor, electromagnetic radiation that has been specularly reflected from the toner application surface; generating, with the specular reflection sensor, a specular reflection output that represents one or more of the properties of the electromagnetic radiation that has been specularly reflected from the toner application surface; receiving, with a diffuse reflection sensor, electromagnetic radiation that has been diffusely reflected from the toner application surface; generating, with the diffuse reflection sensor, a diffuse reflection output that represents one or more of the properties of the electromagnetic radiation that has been diffusely reflected from the toner application surface; and determining, based on the specular reflection output and the diffuse reflection output, at least one scaling factor that can be used to scale outputs generated by one or both of the specular reflection sensor and the diffuse reflection sensor such that when outputs generated by the specular reflection sensor and the diffuse reflection sensor are scaled and then combined to create a combined output, the combined output is substantially free from the noise caused by light loss in the system being calibrated.
Emitter 14 emits electromagnetic radiation that is directed onto toner application surface 12. In some implementations, emitter 14 may include one or more Organic Light Emitting Diodes (“OLEDs”), lasers (e.g., diode lasers or other laser sources), Hot Cathode Fluorescent Lamps (“HCFLs”), Cold Cathode Fluorescent Lamps (“CCFLs”), incandescent lamps, halogen bulbs, received ambient light, and/or other electromagnetic radiation sources. In one embodiment, emitter 14 includes one or more Light Emitting Diodes (“LEDs”). This embodiment may take advantage of the relatively light weight, compactness, low power consumption, low voltage requirements, low heat production, reliability, ruggedness, low cost, and stability of LEDs. However, it should be appreciated that this embodiment is by no means limiting. In some implementations, system 10 may include one or more optical elements (not shown) to guide, focus, filter, and/or otherwise process radiation emitted by emitter 14. For example, one or more lenses may collimate the radiation in a selected direction.
Specular reflection sensor 16 is arranged to receive electromagnetic radiation that has been emitted by emitter 14 and specularly reflected by toner application surface 12. Specular reflection sensor 16 then generates a specular reflection output that represents one or more properties of the received electromagnetic radiation. In one embodiment, specular reflection sensor 16 includes one or more photosensitive detectors positioned to receive at least a portion of the electromagnetic radiation that is emitted by emitter 14 and specularly reflected by toner application surface 12. Based on the received radiation, the one or more photosensitive detectors included in specular reflection sensor 16 generate one or more output signals related to the one or more properties of the received radiation. For example, the one or more output signals may be related to an amount of the radiation, an intensity of the radiation, and/or other properties of the radiation. In one embodiment, the one or more photosensitive detectors include a single photosensitive diode, such as a PIN diode or other photosensitive diode. In other embodiments, other photosensitive devices are included in specular reflection detector 16. For instance, the photosensitive detectors may include a diode array, a CCD chip, a CMOS chip, and/or other photosensitive devices.
As the amount of toner mass present on toner application surface 12 varies, the manner in which electromagnetic radiation that is emitted by emitter 14 and is reflected by toner application surface 12 also varies. More particularly, an amount of electromagnetic radiation emitted from emitter 14 that is specularly reflected by toner application surface 12 and an amount of electromagnetic radiation emitted from emitter 14 that is diffusely reflected by toner application surface 12 vary as a function of an amount of toner mass present on toner application surface 12.
Referring to
Returning to
In some implementations, the relationship between the amount of toner mass present on toner application surface 12 and the amount of electromagnetic radiation received by specular reflection sensor 16 may be described as follows:
Ispec=−a·Mtoner−b·Nloss+c·Nsurf; 1.
where Ispec represents the intensity of the specularly reflected electromagnetic radiation; Mtoner represents the amount of toner mass per unit area present on toner application surface 12; Nloss represents noise present in system 10 due to light loss (e.g., due to absorption, transmission, violations of the uniform diffuse scattering assumption, etc.); Nsurf represents noise present in system 10 due to irregularities in the mirror and/or diffuse properties of toner application surface 12; and a, b, and c represent proportionality coefficients that are greater than 0. As toner application surface 12 ages, it may be subjected to scratches from scratches with paper, cleaner brushes, cleaner blades, and/or other media. The loss of physical integrity due to these scratches may make toner application surface 12 less specular even when toner mass is not present. Nsurf may represent light loss caused by surface imperfections, such as scratches, on toner application surface 12. As has been mentioned above, Nloss and Nsurf tend to increase with wear to toner application surface 12. Experimental data has shown that of the two sources of noise included in equation (1), Nloss and Nsurf, the noise caused by light loss (Nloss) is the dominant noise source.
Based on the relationship illustrated by equation (1), the relationship between the specular reflection output and the amount of toner mass present on toner application surface 12 can be represented as follows:
Vspec=−A·Mtoner−B·Nloss+C·Nsurf 2.
where Vspec represents the specular reflection output; and A, B, and C represent proportionality coefficients. The proportionality coefficients A, B, and C may vary as a function of the intensity of emitter 14, the sensitivity of the one or more photosensitive detectors included in specular reflection sensor 16, the position of specular reflection sensor 16, the position of emitter 14, and/or other variables of system 10.
Diffuse reflection sensor 18 is arranged to receive electromagnetic radiation that has been emitted by emitter 14 and has been diffusely reflected by toner application surface 12. Diffuse reflection sensor 18 then generates a diffuse reflection output that represents one or more properties of the received electromagnetic radiation. In one embodiment, diffuse reflection sensor 18 includes one or more photosensitive detectors positioned to receive at least a portion of the electromagnetic radiation that is emitted by emitter 14 and diffusely reflected by toner application surface 12. Based on the received radiation, the one or more photosensitive detectors included in diffuse reflection sensor 18 generate one or more output signals related to the one or more properties of the received radiation. For example, the one or more output signals may be related to an amount of the radiation, an intensity of the radiation, and/or other properties of the radiation. As was the case with specular reflection sensor 16, in one embodiment, the one or more photosensitive detectors include a single photosensitive diode, such as a PIN diode or other photosensitive diode. In other embodiments, other photosensitive devices are included in diffuse reflection detector 18. For instance, the photosensitive detectors may include a diode array, a CCD chip, a CMOS chip, and/or other photosensitive devices.
As the amount of toner mass present on toner application surface 12 varies, the amount of electromagnetic radiation that is emitted by emitter 14 and diffusely reflected by toner application surface 12 also varies. As was discussed above, in the embodiment in which toner application surface 12 is relatively smooth and reflective, as more toner mass is carried by toner application surface 12 the reflection of the electromagnetic radiation becomes less specular and more diffuse. Again, this is because less of the electromagnetic radiation is specularly reflected by the smooth toner application surface and instead is diffusely reflected by the irregular surface of the toner mass. The increase in diffuse reflection of the electromagnetic radiation due to the increase in toner mass is roughly in proportion to the increase in the toner mass present on toner application surface 12.
In some implementations, the relationship between the amount of toner mass present on toner application surface 12 and the amount of electromagnetic radiation received by diffuse reflection sensor 18 may be described as follows:
Idiff=d·Mtoner−e·Nloss−f·Nsurf; 3.
where Idiff represents the intensity of the diffusely reflected electromagnetic radiation; and d, e, and f represent proportionality coefficients that are greater than 0. As was the case with the intensity of specularly reflected electromagnetic radiation, in equation (3) Nloss is the dominant noise source with respect to Nsurf.
Based on the relationship illustrated by equation (3), the relationship between the diffuse reflection output and the amount of toner mass present on toner application surface 12 can be represented as follows:
Vdiff=D·Mtoner−E·Nloss−F·Nsurf 4.
where Vdiff represents the diff reflection output; and D, E, and F represent proportionality coefficients. The proportionality coefficients A, B, and C may vary as a function of the intensity of emitter 14, the sensitivity of the one or more photosensitive detectors of specular reflection sensor 16, the position of specular reflection sensor 16, the position of emitter 14, and/or other variables of system 10.
It should be appreciated that the illustration of emitter 14, specular reflection sensor 16, and diffuse reflection sensor 18 are provided merely as an exemplary arrangement capable of providing information related to the specular and diffuse reflection of electromagnetic radiation from toner application surface 12. In other embodiments, alternative arrangements of emitters and/or sensors may be implemented. For instance, in one embodiment, a single sensor may be used in conjunction with a plurality of emitters. The emitters including emitters that are arranged to provide specularly reflected electromagnetic radiation to the single sensor and emitters that are arranged to provide diffusely reflected electromagnetic radiation to the single sensor. This embodiment may include the arrangement of emitters and/or sensor disclosed in U.S. Pat. No. 5,204,538, entitled “Densitometer for an Electrophotographic Printer Using Focused and Unfocused Reflecting Beams,” and issued Apr. 20, 1993, the contents of which are hereby incorporated by reference into the present disclosure.
Processor 20 is operatively linked with sensors 16 and 18. This operative link may be embodied in any operative communications link. For example, processor 20 may be linked with sensors 16 via a wired link, a wireless link, a dedicated connection, a network connection, and/or other operative communications links. Processor 20 receives the specular reflection output from specular reflection sensor 16 and the diffuse reflection output from diffuse reflection sensor 18 and based on these outputs determines the amount of toner mass present on toner application surface 12. As is discussed further below, in some embodiments, processor 20 determines the amount of toner mass present on toner application surface 12 from the specular reflection output and the diffuse reflection output based on the relationships described by equations (2) and (4) above.
In the embodiments illustrated in
Calibration module 22 is configured to execute operations that calibrate system 10. For instance, as is discussed further below, in some embodiments calibration module 22 determines one or more scaling factors. The scaling factors may include one or more scaling factors that are applied to the specular reflection output and the diffuse reflection output separately and/or a scaling factor that is applied to a combined output that is a combination of the specular reflection output and the diffuse reflection output. Calibration module 22 determines the scaling factors to enhance the accuracy of system 10 in determining the amount of toner mass present on toner application surface 12. The scaling factors determined by calibration module 22 may be related to coefficients A, B, C, D, E, and F in equations (2) and (4) above.
In some instances Nloss may vary over time. Therefore, in some embodiments, calibration module 22 may determine the scaling factors upon “start-up” of a reprographic system associated with toner application surface 12, at predetermined intervals during the use of a reprographic system associated with toner application surface 12, and/or at other predetermined times. The predetermined intervals during the use of the reprographic system associated with toner application surface 12 are determined to enable the reprographic system to operate within predetermined tolerances. In one embodiment, the predetermined intervals are dictated by the reprographic system and/or system 10. In one embodiment, a user is enabled to enter and/or adjust the predetermined intervals.
Scaling module 24 applies the scaling factors determined by calibration module 22 to outputs in system 10. For example, in some embodiments, scaling module 24 applies scaling factors individually to one or both of the specular reflection output and the diffuse reflection output. The application of scaling factors to outputs in system 10 is discussed further below.
Combination module 26 combines the specular reflection output and the diffuse reflection output to create a combined output. In some of the embodiments in which specular reflection sensor 16 and/or diffuse reflection sensor 18 include photosensitive detectors that generate output signals as the specular reflection output and the diffuse reflection output, combination module 26 may include a differential amplifier that combines the output signals. The differential amplifier of combination module 26 may be embodied in a physical electronic circuit, or in a virtual electronic circuit. For instance, in a virtual electronic circuit the output signals from sensors 16 and 18 may be converted to digital values and may be processed to combine the signals by digital processing, thereby producing a digital signal with substantially the same values as an analog differential amplifier circuit.
As was mentioned above in the discussion of equations (2) and (4), the dominant source of noise in system 10, Nloss, is caused by light lost in system 10, such as light lost to transmission and/or absorption at toner application surface 12, light rays that violate the uniform diffuse scattering assumption, and/or other light lost in system 10. From equations (2) and (4) it can be seen that the impact of this source of noise on the specular reflection output Vspec has a positive correlation with respect to the impact of this source of noise on the diffuse reflection output Vdiff. In light of this correlation, combination of the spectral reflection output with the diffuse reflection output by combination module may include subtracting one of the reflection outputs Vspec or Vdiff. This subtraction will create a combined output with a significantly reduced amount of noise present in comparison with the individual reflection outputs (provided the spectral reflection output and/or the diffuse reflection output are scaled properly).
Determination module 28 determines the amount of toner mass present on the toner application surface based on the combined output created by combination module 26. The determination of the amount of toner mass from the combined output is discussed further below.
In some instances, system 10 includes a storage module 30. Storage module 30 is operatively linked to processor 20 and operates to store information for access by processor 20. For example, some or all of modules 22, 24, 26, and/or 28 may store information to storage module 30 and/or access, manipulate, and/or interact with information stored on storage module 30. In one embodiment, storage module 30 includes an electronically readable medium such as a magnetic medium (e.g., a hard drive), an optical medium (e.g., an optical disc), a solid state medium (e.g., a flash drive), etc.
At an operation 34 electromagnetic radiation is directed to become incident on the toner application surface. In one embodiment, operation 34 is executed by the emission of electromagnetic radiation emitter 14 onto toner application surface 12, as shown in
Referring back to
A specular reflection output is generated at an operation 38. The specular reflection output is representative of one or more of the properties of the electromagnetic radiation received at operation 36. For example, the specular reflection output may be representative of an intensity, an amount, and/or other properties of the electromagnetic radiation received at operation 36. In one embodiment, operation 38 is performed by specular reflection sensor 16 (
At an operation 40, the electromagnetic radiation that is diffusely reflected from the toner application surface is received. For instance, the electromagnetic radiation may be received by a sensor capable of detecting one or more properties of the electromagnetic radiation. In one embodiment, operation 40 is performed by diffuse reflection sensor 18 (
A diffuse reflection output is generated at an operation 42. The diffuse reflection output is representative of one or more of the properties of the electromagnetic radiation received at operation 40. For example, the diffuse reflection output may be representative of an intensity, an amount, and/or other properties of the electromagnetic radiation received at operation 40. In one embodiment, operation 42 is executed by diffuse reflection sensor 18 (
At operations 44 and 46 the outputs generated by operations 38 and 42 are scaled and combined, respectively. As was mentioned above with respect to combination module 26 (
By way of illustration, in one embodiment, differencing of the specular reflection and diffuse reflection outputs (as described by equations 2 and 4, respectively) generated by a system executing method 32 can be represented as:
Vdiff−Vspec=D·Mtoner−E·Nloss−F·Nsurf+A·Mtoner+B·Nloss−C·Nsurf; 5.
Since the dominant source of noise in the individual outputs is Nloss, for the purposes of this discussion the Nsurf terms may be removed from equation (5). Upon removal of the Nsurf terms, equation (5) simplifies to:
Vdiff−Vspec=Mtoner·(A+D)+Nloss·(B−E) 6.
Thus, the combined signal includes a component that is proportional to the amount of toner mass present on the toner application surface (Mtoner·(A+D)), and a component that is proportional to the common signal noise represented by Nloss(Nloss·(B−E)). From equation (6) it should be apparent that by scaling one or both of the specular reflection output and/or the diffuse reflection output appropriately at operation 44, the (B−E) term in equation (6) can be reduced to substantially zero, effectively eliminating (or at least significantly reducing) the impact of noise in system 10 due to light loss on the combined signal created by operation 46.
For example, if the specular reflection output, Vspec, is scaled at operation 44 by a scaling factor that is substantially equal to E/B, then combination at operation 46 by differencing the specular reflection output and the diffuse reflection output would result in the following combined output (compare with equation (6)):
It should be appreciated from equation (7) that scaling the specular reflection output, Vspec, at operation 44 by a scaling factor that is substantially equal to E/B results in the term associated with noise present in system 10 due to light loss, Nloss, falling out of the combined output created by operation 46. In other words, the combined ouput expressed by equation (7) simplifies to:
While the above-illustrated example discusses scaling only one of the reflection outputs, the specular reflection output, at operation 44, this is not intended to be limiting. It should be appreciated that the same result (the cancellation of the noise present in the system due to light loss) may be effected by scaling just the other reflection output or scaling both of the reflection outputs at operation 44. It can further be seen from the foregoing that the scaling and combination of the reflection outputs to create a combined output that is substantially free from noise enables the toner application surface to be used without recalibrating a printing device in which the toner application surface is installed to account for degradation of the toner application surface. This is due to the cancellation of at least some of the effects of this degradation (e.g., noise due to light loss) achieved by appropriately scaling one or both of the reflection outputs at operation 44 and then combining the scaled outputs at operation 46. In one embodiment, operations 44 and 46 are performed by modules 24 and 26 of system 10 illustrated in
Returning to
At an operation 52, a known amount of toner is applied to the toner application surface. For example, the known amount of toner can be substantially zero. In one embodiment, operation 52 is executed by applying the known amount of toner to toner application surface 12 (
At an operation 54 electromagnetic radiation is directed to become incident on the toner application surface. In one implementation, operation 54 is executed by the emission of electromagnetic radiation emitter 14 onto toner application surface 12, as shown in
Referring back to
A specular reflection output is generated at an operation 58. The specular reflection output represents one or more of the properties of the electromagnetic radiation received at operation 56. For example, the specular reflection output may represent an intensity, an amount, and/or other properties of the electromagnetic radiation received during operation 56 from the toner application surface. In one embodiment, operation 58 is performed by specular reflection sensor 16 (
At an operation 60, the electromagnetic radiation that is diffusely reflected from the toner application surface is received. For instance, the electromagnetic radiation may be received by a sensor capable of detecting one or more properties of the electromagnetic radiation. In one embodiment, operation 60 is performed by diffuse reflection sensor 18 (
A diffuse reflection output is generated at an operation 62. The diffuse reflection output is representative of one or more of the properties of the electromagnetic radiation received at operation 60. For example, the diffuse reflection output may be representative of an intensity, an amount, and/or other properties of the electromagnetic radiation received during operation 60 from the toner application surface. In one embodiment, operation 62 is executed by diffuse reflection sensor 18 (
At an operation 64 at least one scaling factor is determined based on the specular reflection output generated by operation 58 and the diffuse reflection output generated by operation 62. In the implementation in which the known amount of toner mass present on the toner application surface is zero, and using the form of equation (2), the specular reflection output may be expressed in a simplified form (e.g., dropping the Nsurf term for the reasons discussed above) as:
Vspec=−B·Nloss. 9.
The diffuse reflection output may be expressed, using the form of equation (4) in a similarly simplified form as:
Vdiff=−E·Nloss. 10.
In some embodiments, operation 64 includes dividing one of the reflection outputs by the other reflection output to determine an appropriate scaling factor. For example, the division of the diffuse reflection output expressed in equation 10 by the specular reflection output expressed in equation 9 would simplify to E/B. As is discussed above with respect to method 32, E/B is a scaling factor that can be used to scale the specular reflection output so that when the specular reflection output and the diffuse reflection output are combined to create a combined output, the combined output is substantially free from noise caused by light loss in the system being calibrated.
It should be appreciated that although in the example in which the known toner mass amount is zero the determination of at least one scaling factor is somewhat simplified, in other embodiments other known amounts of toner may be used. For instance, two or more different amounts of toner may be used and then the sets of reflection outputs can be divided and solved for the at least one scaling factor as simultaneous equations.
In some implementations, the determination of the at least one scaling factor at operation 64 is based on specular reflection outputs and diffuse reflection outputs that correspond to readings taken by the specular reflection outputs and the diffuse reflection outputs at a plurality of locations on the toner application surface. As should be apparent, this may enhance the overall accuracy of the determined scaling factors by incorporating the reflection signature of the toner application surface for a relatively large portion of the toner application surface (e.g., substantially all of the toner application surface) into the calibration, rather than just a single point on the surface. For example, in one embodiment in which the toner application surface is provided by a belt, the toner application surface is actuated such that the plurality of locations become sequentially located within the electromagnetic radiation being directed towards the toner application surface. For instance, the electromagnetic radiation may be directed to a fixed point in space, and the belt that provides the toner application surface is driven by rollers past the fixed point.
In embodiments in which readings are taken by the specular reflection sensor and the diffuse reflection sensor at a plurality of locations on the toner application surface, a variety of algorithms may be implemented to determine the at least one scaling factor from the plurality of readings. For example, in one embodiment at least one scaling factor is determined (e.g., via the method described above) for each of the plurality of locations on the toner application surface, and then the plurality of scaling factors are averaged, or otherwise aggregated, to determine a aggregated scaling factor to be used by the system. In another embodiment, the outputs from the plurality of readings by the specular reflection sensor are averaged, or otherwise aggregated, to determine an aggregated specular reflection output. Similarly, the outputs from the plurality of readings by the diffuse reflection sensor are averaged, or otherwise aggregated, to determine an aggregated diffuse reflection output. Then the aggregated specular reflection output and the aggregated diffuse reflection output are used to determine the at least one scaling factor (e.g., by division as described above).
In one embodiment, operation 64 is performed by calibration module 22 (
At an operation 68, a known amount of toner is applied to the toner application surface. In one embodiment, operation 68 is executed by applying the known amount of toner to toner application surface 12 (
At an operation 70 electromagnetic radiation is directed to become incident on the toner application surface. In one implementation, operation 70 is executed by the emission of electromagnetic radiation emitter 14 onto toner application surface 12, as shown in
Referring back to
A specular reflection output is generated at an operation 74. The specular reflection output represents one or more of the properties of the electromagnetic radiation received at operation 72. For example, the specular reflection output may represent an intensity, an amount, and/or other properties of the electromagnetic radiation received during operation 72 from the toner application surface. In one embodiment, operation 74 is performed by specular reflection sensor 16 (
At an operation 76, the electromagnetic radiation that is diffusely reflected from the toner application surface is received. For instance, the electromagnetic radiation may be received by a sensor capable of detecting one or more properties of the electromagnetic radiation. In one embodiment, operation 76 is performed by diffuse reflection sensor 18 (
A diffuse reflection output is generated at an operation 78. The diffuse reflection output is representative of one or more of the properties of the electromagnetic radiation received at operation 76. For example, the diffuse reflection output may be representative of an intensity, an amount, and/or other properties of the electromagnetic radiation received during operation 76 from the toner application surface. In one embodiment, operation 78 is executed by diffuse reflection sensor 18 (
At operations 80 and 82 the outputs generated by operations 74 and 78 are scaled and combined, respectively. As has been discussed above, the combination of the specular reflection output and the diffuse reflection output can be executed to create a combined output with a reduced amount of noise in comparison with the individual specular reflection and diffuse reflection outputs. For instance, in one embodiment, the specular reflection output and the diffuse reflection output can be combined at operation 82 by differencing the outputs. At operation 80, one or both of the specular reflection output and/or the diffuse reflection output may be scaled (e.g., using the at least one scaling factor determined by method 50) so that when the reflection outputs are combined at operation 82 the noise present in the combined output is further suppressed. In one embodiment, operations 44 and 46 are performed by modules 24 and 26, respectively, of system 10 (
The combined output created at operation 82 becomes a calibration point that can be used to determine the amount of toner mass on the toner application surface. At an operation 84 a decision is made as to whether enough calibration points have been determined to enable a determination between the amount of toner mass on the toner application surface and the combination of the outputs of the spectral reflection sensor and the diffuse reflection sensor. In some implementations, the number of calibration points required may be two or more. In one embodiment, operation 84 is executed by calibration module 22 (
If it is determined at operation 84 that more calibration points are needed, then method 66 proceeds back to operation 68 and a (different) known amount of toner is applied to the toner application surface so that another calibration point can be determined. If it is determined at operation 84 that no more calibration points are needed, then method proceeds to an operation 86.
At operation 86 the calibration points (e.g., the combined outputs for two or more different known toner mass amounts) are used to determine the correlation between (i) the combined outputs of the spectral reflection sensor and the diffuse reflection sensor, and (ii) the amount of toner mass present on the toner application surface. For example, in one embodiment a curve-fitting algorithm is used to determine a curve that fits to the calibration points and describes the amount of toner mass present as a function of the combined output of the reflection sensors. For instance, the curve may take the following form (derived from equations (2) and (4)):
where Vcombined is the combined output (specified in equation (8) as
where E/B is the scaling factor). In another embodiment, the calibration points are used to generate a look-up table that returns an amount of toner mass present in response to the combined output of the reflection sensors.
It should be appreciated that although the subject matter of the disclosure has been set forth with respect to the environment of a printing device, this has been done for illustrative purposes and is not intended to be limiting. For example, other systems that include implement a spectral reflection sensor that (i) is co-located with a diffuse reflection sensor and (ii) experiences a common source of noise with the diffuse reflection sensor are contemplated by this disclosure. In such systems, the output of the spectral reflection sensor and the output of the diffuse reflection sensor may be scaled and combined in the manner described above to achieve substantially the same results.
Thus, the subject matter of this application has been described in conjunction with the specific embodiments outlined above, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, the preferred embodiments as set forth above are intended to be illustrative, not limiting. Various changes may be made without departing from the spirit and scope of the following claims.
| Number | Name | Date | Kind |
|---|---|---|---|
| 5204538 | Genovese | Apr 1993 | A |
| 20040208661 | Kitagawa et al. | Oct 2004 | A1 |
| Number | Date | Country | |
|---|---|---|---|
| 20080089708 A1 | Apr 2008 | US |
