The present invention relates to an image forming apparatus, and more particularly, to an image forming apparatus such as a printing apparatus, a copying machine, a laser beam printer, or a facsimile machine.
An image forming apparatus using an electrophotographic system is configured to execute calibration to maintain density at a fixed level or correct color misregistration at the time of printing when an environment in which the image forming apparatus is installed has changed. Specifically, when an indicator indicating a change in environment since previous calibration has changed by a predetermined amount, the image forming apparatus actually forms a patch for calibration on an intermediate transfer member, and measures the color of the formed patch. A method of determining an image forming condition in this manner is proposed (Japanese Patent Application Laid-Open No. 2000-238341). Further, a method of predicting the image forming condition based on the amount of change in environment is also proposed (Japanese Patent Application Laid-Open No. 2017-037100).
However, the following problem occurs when whether to execute calibration is determined based only on the actually measured change amount as in the related-art example. Specifically, determination that takes a subsequent change in environment into consideration cannot be performed, and thus there is a fear in that calibration is executed at an unrequired timing, and downtime consequently occurs. Further, when the image forming condition is predicted based on the amount of change in environment as in another related-art example, downtime can be minimized, but there is a fear in that accuracy of correction deteriorates due to a prediction error compared to actual measurement.
There is provided an image forming apparatus, which is configured to execute calibration for controlling an image forming condition, the image forming apparatus comprising: a first detection unit configured to detect an environmental state in which the image forming apparatus is installed; a prediction unit configured to predict, based on a plurality of detection results detected by the first detection unit in a first period, a change in the environmental state in a second period after the first period; and a setting unit configured to set a timing of executing the calibration in the second period based on the change in the environmental state predicted by the prediction unit.
Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.
Now, description is made in detail of embodiments of the present invention with reference to the drawings.
In Embodiment 1, there is proposed a method of determining a timing of executing control (hereinafter referred to as “calibration”) for optimizing an imaging forming condition by predicting a change in environment and performing density correction, color misregistration correction, or the like based on the predicted result.
[Description of Configuration of Image Forming Apparatus of Embodiment 1:
A cassette 17 storing a sheet S, which is a storage medium, is mounted to a lower part of the image forming apparatus 100. Further, a transfer roller is provided so that the sheet S passes through a secondary transfer roller 69 and a fixing device 74, and then is delivered to the top of the image forming apparatus 100. That is, a feed roller 54 for separately feeding the sheet S in the cassette 17 one by one, and a registration roller pair 55 for synchronizing the latent image formed on the photosensitive drum 1 with the sheet S are provided.
Further, a belt unit 5 for transferring a toner image formed on each photosensitive drum 1 is provided above the process cartridge 70. The belt unit 5 includes a driving roller 56, a driven roller 57, a primary transfer roller 58 arranged at a position opposed to the photosensitive drum 1 of each color, and an opposing roller 59 arranged at a position opposed to the secondary transfer roller 69. A transfer belt 9, which is an intermediate transfer member, is wound around those rollers. The transfer belt 9 rotatably moves in such a manner as to be opposed to and in contact with all the photosensitive drums 1, and a voltage is applied to the primary transfer roller 58, to thereby transfer a toner image from the photosensitive drum 1 onto the transfer belt 9 (primary transfer). Voltages are applied to the secondary transfer roller 69 and the opposing roller 59 arranged in the transfer belt 9, to thereby transfer a color toner image on the transfer belt 9 onto the sheet S (second transfer).
A density sensor 40, which is a second detection unit, is arranged opposite to the transfer belt 9. The image forming apparatus 100 has a function of executing calibration to detect the density of a patch by the density sensor 40 in order to ensure accurate color reproducibility and color stability. The patch refers to a toner image to be detected by the density sensor 40, and is formed on the transfer belt 9. An environmental sensor 50, which is a first detection unit for detecting an environmental state (environmental information) of an environment in which the image forming apparatus is installed, is mounted to the image forming apparatus. The environmental sensor 50 is mounted to a portion at which the environmental sensor 50 is not influenced by heat generated by the image forming apparatus itself and an indicator (e.g., temperature, humidity, and absolute humidity) indicating the environmental state of the environment in which the image forming apparatus is installed can be detected.
[Description of System Configuration of Image Forming Apparatus According to Embodiment 1:
The following procedure is performed when an image is actually formed on the sheet S. First, the controller 650 loads image information subjected to image processing by the image processing portion 651 onto an image memory (not shown). The controller 650 outputs the image information on the image memory to the image forming engine 620 via the video interface 640 in synchronization with an image output timing received from the image forming engine 620.
The image forming engine 620 includes a main control portion 610 and an image forming portion 630. The image forming portion 630 includes the process cartridge 70, the belt unit 5, the primary transfer roller 58, the secondary transfer roller 69, the fixing device 74, the density sensor 40, and the environmental sensor 50 described above. The main control portion 610 includes a calibration portion 603, an environmental change amount predicting portion 604, a timing determining portion 605, and a memory 609. The calibration portion 603, which is an execution unit, is configured to execute calibration. The environmental change amount predicting portion 604, which is a prediction unit, is configured to predict an amount of change (hereinafter referred to as “environmental change amount”) in indicator indicating an environment in which the image forming apparatus is installed, based on information detected by the environmental sensor 50. The timing determining portion 605, which is a setting unit, is configured to determine (set) a calibration execution timing based on a result predicted by the environmental change amount predicting portion 604. Those series of control procedures are executed by using a CPU or an ASIC, for example. The memory 609, which is a storage unit, accumulates a plurality of pieces of information detected by the environmental sensor 50.
[Description of Density Sensor in Embodiment 1:
In actuality, the color of the toner image changes due to, for example, a change in environment in which the image forming apparatus is used, a use history of various kinds of consumables or the like included in the image forming apparatus, or a change in state of a main body of the image forming apparatus accompanying operation of the image forming apparatus. Thus, the image forming apparatus executes calibration for density correction to set the image forming condition (image creating condition) to an appropriate value at a predetermined timing so as to constantly stabilize the color.
[Description of Environmental Sensor and Threshold Value for Determining Environmental Change in Embodiment 1]
In Embodiment 1, information (result of detection by environmental sensor 50) obtained from the environmental sensor 50 is an absolute humidity, for example. The absolute humidity changes due to a change in environment with respect to an absolute humidity obtained when previous calibration has been executed serving as a reference. Further, a change amount at a time when the absolute humidity has changed such that calibration is required to be executed again because of occurrence of large image variation due to the change in environment is hereinafter referred to as “environmental change threshold value”. Specifically, when the environmental change amount with respect to the absolute humidity serving as a reference becomes equal to or larger than the environmental change threshold value as a result of detection by the environmental sensor 50, calibration is executed. For example, the environmental change threshold value (predetermined change amount) is set as 5 g/m3 for the absolute humidity. The environmental sensor 50 of the image forming apparatus monitors the absolute humidity. The image forming apparatus executes calibration when the absolute humidity detected by the environmental sensor 50 has changed by the environmental change threshold value (5 g/m3 or more) (predetermined change amount or more) or more with respect to the previous (reference) absolute humidity.
[Description of Environmental Change Amount Predicting Portion in Embodiment 1:
Regarding the unit for predicting a specific environmental change amount, an absolute humidity over the last three weeks, which is a first period, is averaged for prediction every hour (every predetermined period). Thus, the main control portion 610 stores a result detected by the environmental sensor 50 every hour, for example, into the memory 609. The memory 609 accumulates a plurality of pieces of information (first information) for the last three weeks, which are detected by the environmental sensor 50, for example. The environmental change amount predicting portion 604 reads out those pieces of information for the last three weeks, which are stored in the memory 609, averages results of detection by the environmental sensor 50 every hour, for example, and predicts an environmental change amount in one day, which is a second period subsequent to the last three weeks. For example, the environmental change amount predicting portion 604 averages an absolute humidity at 9 o'clock for the three weeks, and predicts the absolute humidity at 9 o'clock. Next, the environmental change amount predicting portion 604 averages an absolute humidity at 10 o'clock for the three weeks, and predicts the absolute humidity at 10 o'clock. In this manner, the environmental change amount predicting portion 604 predicts the absolute humidity every hour, to thereby predict the change in absolute humidity in one day and obtain a prediction result as shown in
It is easily assumed that the time band granularity is changed or the averaging period is changed in order to improve the accuracy of predicting the environmental change amount. Further, it can be assumed that the accuracy is improved greatly by excluding data obtained at a holiday of the office from averaging processing. Further, when working hours of Z company are from 9 o'clock to 17 o'clock, for example, and the power supply of the image forming apparatus is turned on only during the working hours, the environmental change on a time band other than the working hours may not be obtained in actuality. Thus, it is possible to predict the environmental change only during the working hours. In the case of Company Z shown in
[Description of Processing of Determining Calibration Execution Timing in Embodiment 1:
In Step S101, as described with reference to
[Timing of Executing Calibration in Embodiment 1:
Now, description is made of a specific calibration execution timing in Embodiment 1 with reference to
(Period in which Data on Past Absolute Humidity is not Accumulated)
When this situation is applied to Company Z, calibration is executed at the following timing. First, as shown in the point A of
(Period in which Data on Past Absolute Humidity is Accumulated)
It is assumed that about three weeks have elapsed since the installation of the image forming apparatus, and data on the absolute humidity is gradually accumulated in the memory 609. Then, the environmental change amount at the installed place of the image forming apparatus can be predicted. For example, in Company Z, it is understood that the absolute humidity is about 2.5 g/m3 at 9 o'clock, which is the working start time, and the maximum absolute humidity reached through the change between 9 o'clock and 17 o'clock, which is the working end time, is about 8.5 g/m3. Thus, the environmental change amount predicting portion 604 can predict the maximum variation of about 6 (=8.5-2.5) g/m3 in one day for the absolute humidity in the environment of Company Z based on the prediction of
In this case, it suffices that the calibration execution timing is determined in the following manner in order to prevent occurrence of downtime due to calibration as much as possible. Specifically, as shown in the point C of
As described above, in Embodiment 1, the timing determining portion 605 can determine an optimal timing in an environment in which the image forming apparatus is installed by adopting the environmental change amount predicting portion 604. Specifically, when the maximum environmental change amount in one day, which is predicted by the environmental change amount predicting portion 604, is equal to or larger than the environmental change threshold value and smaller than twice the value, the timing determining portion 605 executes calibration at a timing of occurrence of change by half the predicted maximum environmental change amount. With this, it is possible to minimize downtime while at the same time providing stable image quality. Calibration is not limited to density control, and it is easily considered that calibration may also be applied to color misregistration adjustment. Further, the environmental change is also not limited to the absolute humidity, and it is easily considered that the environmental change may also be applied to a temperature and a humidity.
As described above, according to Embodiment 1, it is possible to minimize downtime while at the same time providing stable image quality.
In Embodiment 2, there is proposed a method of determining the calibration timing by using prediction of usage by a user in addition to prediction of the environmental change amount. In Embodiment 2, details overlapping with those of Embodiment 1 are omitted, and the same reference symbol is assigned to the same configuration or unit for description.
[Description of System Configuration of Image Forming Apparatus in Embodiment 2:
[Description of User Use Prediction Portion in Embodiment 2:
Similarly to the prediction of the environmental change amount described with reference to
It is easily assumed that the time band granularity is changed or the averaging period is changed in order to improve the accuracy of prediction. Further, it can be assumed that the accuracy is improved greatly by excluding data obtained at a holiday of the office from averaging processing. Further, when the working hours of Company Z are from 9 o'clock to 17 o'clock, and the power supply of the image forming apparatus is turned on only during the working hours, user usage prediction on a time band other than the working hours may not be performed in actuality. Thus, it is also possible to perform user usage prediction only during the working hours. The number of prints is used for user usage prediction, but it is easily assumed that a similar effect can be expected also by adopting the operation time (usage time) of the image forming apparatus.
[Description of Processing of Determining Calibration Execution Timing in Embodiment 2:
Step S200 and Step S203 are similar to the processing of Step S100 and Step S103 of
In Step S201, when the main control portion 610 has determined that both of environmental change amount prediction and user usage prediction have been completed, the main control portion 610 advances the processing to Step S202. In Step S202, the main control portion 610 obtains the environmental change prediction amount of that day predicted by the environmental change amount predicting portion 604 and the user usage prediction of that day predicted by the user usage prediction portion 606.
(Calibration Execution Timing in Embodiment 2:
Now, description is made of the processing of determining the specific calibration execution timing in Embodiment 2 with reference to
(Period in which Data on Past Environmental Change Amount and User Usage Condition is not Accumulated)
In a period in which the environmental change amount or the user usage condition cannot be predicted yet, as in the related art, for example, calibration is executed at the time of turning on the power supply, and after that, calibration is executed again when a predetermined environmental change has occurred. That is, on the basis of the related-art method, calibration is executed in the point A and the point B of
(Period in which Data on Past Environmental Change Amount and User Usage Condition is Accumulated)
When about three weeks have elapsed and the environmental change amount and user usage condition can be predicted at the installed place of the image forming apparatus, the fact that the environmental change amount in one day is about 6 g/m3, the user usage amount is large between 10 o'clock and 11 o'clock and between 11 o'clock and 12 o'clock, and the user usage amount is conversely small between 12 o'clock and 13 o'clock can now be predicted. That is, as described in Embodiment 1, the timing determining portion 605 determines that execution of calibration at 10:30 shown in the point C of
In view of this, the timing determining portion 605 in Embodiment 2 changes the calibration execution timing within a range (within predetermined range) of the environmental change threshold value of 5 g/m3 with the absolute humidity at the time of previous calibration serving as a starting point. Specifically, the timing determining portion 605 changes the calibration execution timing to a time band having the lowest user usage prediction until 13 o'clock. With this, it is possible to reduce the number of users experiencing downtime. Specifically, as shown in the point C′ of
As described above, in Embodiment 2, the calibration execution timing is determined by using the result of prediction by the user usage prediction portion 606 in addition to the result of prediction by the environmental change amount predicting portion 604. With this, it is possible to determine an optimal calibration execution timing in consideration of the environment in which the image forming apparatus is installed and the usage condition of the user, to thereby be able to minimize the downtime while at the same time providing a stable image quality.
As described above, according to Embodiment 2, it is possible to minimize downtime while at the same time providing the stable image quality.
Embodiment(s) of the present invention can also be realized by a computer of a system or apparatus that reads out and executes computer executable instructions (e.g., one or more programs) recorded on a storage medium (which may also be referred to more fully as a ‘non-transitory computer-readable storage medium’) to perform the functions of one or more of the above-described embodiment(s) and/or that includes one or more circuits (e.g., application specific integrated circuit (ASIC)) for performing the functions of one or more of the above-described embodiment(s), and by a method performed by the computer of the system or apparatus by, for example, reading out and executing the computer executable instructions from the storage medium to perform the functions of one or more of the above-described embodiment(s) and/or controlling the one or more circuits to perform the functions of one or more of the above-described embodiment(s). The computer may comprise one or more processors (e.g., central processing unit (CPU), micro processing unit (MPU)) and may include a network of separate computers or separate processors to read out and execute the computer executable instructions. The computer executable instructions may be provided to the computer, for example, from a network or the storage medium. The storage medium may include, for example, one or more of a hard disk, a random-access memory (RAM), a read only memory (ROM), a storage of distributed computing systems, an optical disk (such as a compact disc (CD), digital versatile disc (DVD), or Blu-ray Disc (BD)™), a flash memory device, a memory card, and the like.
While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
This application claims the benefit of Japanese Patent Application No. 2019-104026, filed Jun. 3, 2019, which is hereby incorporated by reference herein in its entirety.
Number | Date | Country | Kind |
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2019-104026 | Jun 2019 | JP | national |