JP2007310030A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of reducing image data line memory required to estimate a quantity of toner consumption while accurately estimating the quantity of toner consumption regardless of an image type. <P>SOLUTION: The image forming apparatus includes an image data line memory 104 and a video count operating section 105. The video count operating section 105 includes: a weight estimation operating section 201 that performs a weight operation for a plurality of pixels surrounding a target pixel 301 according to at least the density of the target image 301, the distance of the target pixel 301, or a position corresponding to a target pixel 101; a cumulative addition operating section 203 that cumulatively adds video count values before the target pixel 301, as the result of the weight operation in the same main scanning direction; and a video count estimation operating section 204 that estimates a quantity of toner consumption of the target pixel 101 based on updated image data in the image data line memory 104 and the result of the cumulative addition. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus capable of predicting toner consumption.

  In a developing device of an image forming apparatus, a two-component developer mainly composed of toner particles (carbon particles or the like) and carrier particles is generally used. In the case of the image forming apparatus using the two-component developer, toner particles in the developing device are consumed by forming an image, and the concentration of toner particles relative to the carrier particles, that is, the toner concentration is lowered. In order to maintain the image quality, the toner concentration needs to be constant. For this reason, it is necessary to replenish toner particles as needed according to the decrease in toner particles so that the toner concentration becomes constant.

  As a toner concentration measuring means for measuring the toner concentration, a magnetic permeability sensor or the like is often used. This magnetic permeability sensor detects the decrease in the toner particles by detecting the change in the magnetic permeability by utilizing the property that the magnetic permeability increases as the toner particles decrease. However, since this magnetic permeability sensor is expensive, there is a toner consumption prediction means for predicting the toner particle consumption as means for detecting the toner concentration without using the magnetic permeability sensor (see, for example, Patent Document 1). ). This is to detect the number of continuous pixels in the main scanning direction by counting the number of continuous video signals that modulate the laser light source during image formation, and based on the relationship between the number of continuous pixels and the amount of toner consumed per pixel. The toner consumption amount due to the formation is calculated.

  At this time, it is known that the toner consumption actually consumed varies depending not only on the number of continuous pixels and isolated point pixels in the main scanning direction but also on the number of continuous pixels and isolated point pixels in the sub scanning direction. .

  Specifically, as shown in FIG. 6, when toner is attached to a square pixel 401 on a printing surface composed of 3 × 3 pixels, the toner is attached to a circular laser spot 402. This is because if the toner adheres to a range smaller than the pixel 401 at the time of fixing, the image is not sufficiently filled.

  As described above, since the toner is attached to a range larger than the pixel 401, when the five pixels 401 are painted as shown in FIG. 4, an overlapping portion 403 where the pixels overlap is generated. Since the overlapping portion 403 has a larger amount of charge removal from the photoconductor than the other portions, the toner adhesion amount increases, and a difference in toner consumption occurs between the overlapping portion 403 and other portions.

  In addition, as shown in FIG. 7, when toner is not attached to the surrounding pixels but only to the laser spot 501 of one pixel, the surrounding pixels have a toner adhesion amount of the pixel due to the influence. It is generally known that the toner is less than or does not adhere to the toner.

  This is because, in the exposure process in which the photosensitive member is irradiated with a laser to remove the charge on that portion, the time for laser irradiation is very short, so that it is not possible to remove the charge necessary and sufficient for the toner to adhere. Because. For the above reason, the isolated point pixel is also a cause of an error in toner consumption.

  In the case of image data as shown in FIG. 8, the central pixel can be regarded as an isolated point pixel 601. It is necessary to consider that the isolated point pixel 601 is affected by the periphery because the toner does not easily adhere as described above.

  In order to achieve higher image quality, control is also performed to change the laser irradiation position within one pixel as shown in FIG. For example, the irradiation position of the laser spot 702 of the peripheral pixel is shifted outward with respect to the laser spot 701 of the target pixel. At this time, although the image pixels are adjacent to each other, the overlapping of the laser spots as shown in the overlapping portion 403 in FIG. 6 does not occur. Therefore, as a result, there is a difference in toner consumption from the case of the toner image due to the overlapping of laser spots in FIG.

  In order to solve such a problem, there is a technique for predicting (video counting) the toner consumption amount consumed for toner formation with reference to many peripheral pixels centering on the target pixel with high accuracy. .

Further, in order to eliminate an error between the predicted toner consumption amount and the actual toner consumption amount, error elimination processing is actually executed a plurality of times for several tens of prints. The error elimination processing is processing for printing a toner density measurement pattern inside the image forming apparatus, optically measuring the density of the print pattern using a sensor, and adjusting the toner density.
Japanese Patent No. 3483001

  However, when predicting and calculating the toner consumption with high accuracy, a large number of image data line memories are required to refer to a plurality of peripheral pixels, which inevitably leads to an increase in cost.

  Further, when performing the above error elimination processing, the printing processing must be interrupted even if it is in the middle of the printing processing. In particular, when the error elimination processing frequency is high, a unit that is a measure of the performance of the image forming apparatus There arises a problem that the number of printed sheets per hour is greatly reduced. Further, there is a problem that the cost of each means necessary for the error elimination process leads to an increase in the cost of the entire image forming apparatus.

  An object of the present invention is to provide an image forming apparatus capable of reducing the image data line memory necessary for predicting the toner consumption amount while accurately predicting the toner consumption amount regardless of the image type. There is.

  In order to achieve the above object, the image forming apparatus according to claim 1 is an image forming apparatus including an image data line memory and a video count prediction calculation unit, wherein the video count calculation unit includes a plurality of pixels centered on a target pixel. For the surrounding pixels, a weighting prediction calculation unit that performs weighting calculation according to at least one of the density of the target image, the distance from the target pixel, and the position with respect to the target pixel, and the weighting for the same main scanning direction. As a calculation result, a cumulative addition calculation unit that cumulatively adds the video count values before the target pixel, and the image data in the updated image data line memory and the cumulative addition result are used to predict and calculate the toner consumption amount of the target pixel. And a video count prediction calculation unit.

  According to the present invention, since the video count value before the pixel of interest is cumulatively added by the cumulative addition calculation unit, the toner consumption amount is predicted while accurately predicting the toner consumption amount regardless of the image type. It is possible to reduce the image data line memory necessary for the image data.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a diagram schematically showing a configuration of a scanning optical system of an image forming apparatus according to an embodiment of the present invention.

  In FIG. 1, the scanning optical system of the image forming apparatus includes a laser unit 101 having a plurality of light sources, and a rotary polygon mirror 102 that reflects the laser irradiated from the laser unit 101 and writes it in the main scanning direction on the photoconductor 103. It has.

  Further, the image forming apparatus includes an image data line memory 104 that stores image data necessary for forming an image, and a video count calculation unit 105 that calculates a count value corresponding to the consumption amount of the developer. .

  A plurality of lasers of the laser unit 101 modulated by the image data stored in the image data line memory 104 are irradiated to the rotating polygon mirror 102 that rotates at high speed. The plurality of laser beams reflected by the rotary polygon mirror 102 are irradiated on the photoconductor 103 and written in the main scanning direction to form an electrostatic latent image on the photoconductor 103. This electrostatic latent image is developed by a developing device (not shown) to form a visible image (toner image).

  The video count prediction calculation unit 105 stores in the image data line memory 104 the cumulative addition result that has been cumulatively added up to the pixel of interest necessary for video counting, for example, a 7 × 7 pixel centered on the pixel of interest. With reference to the peripheral pixels, video counting is performed with the same accuracy as measuring the actual toner consumption consumed to form the toner image.

  FIG. 2 is a diagram illustrating the configuration of the video count calculation unit 105 in FIG. 1 in the order of image data processing.

  In FIG. 2, the video count calculation unit 105 includes a weighting calculation unit 201, a cumulative addition calculation unit 203, and a video count prediction calculation unit 204. These components function as follows.

  As illustrated in FIG. 3A, the weighted prediction calculation unit 201 moves the target pixel 301 indicated by “a” as needed in the main scanning direction with time, and further performs main / sub-scanning directions centered on the target pixel 301. For each of the plurality of peripheral pixels, a weighting calculation is performed according to at least one of the density of the target image 301, the distance from the target pixel 301, and the position with respect to the target pixel 101 using a look-up table. The calculation result is stored in the image data line memory 104 (FIG. 3A).

  By using the lookup table, at least one of the density of the target image 301, the distance from the target pixel 301, and the position with respect to the target pixel 101 can be easily considered. As an example of weighting, FIG. 4 shows the case where the isolated point pixel 601 exists, and FIG. 5 shows the case where the laser spots 701 and 702 do not overlap.

  Next, the cumulative addition calculation unit 203 cumulatively adds the video count values before the target pixel 301 as the weighting calculation result with respect to the same main scanning direction, and stores the cumulative addition result in the image data line memory 104. (FIG. 3B). As a result, the area of the image data line memory 104 can be reduced, and the image data in the image data line memory 104 can be sequentially updated each time scanning is performed (FIG. 3C).

  The video count prediction calculation unit 204 performs prediction calculation (video count) on the toner consumption amount of the target pixel 101 using the updated image data in the image data line memory 104 and the cumulative addition result. In this case, video counting can be performed with the same accuracy as referring to a wide range of peripheral pixels.

  As described above, it is possible to predict the toner consumption more accurately by considering the image data of the peripheral pixels, the isolated point pixels, and the position data of the peripheral pixels based on a certain target pixel. As a result, it is possible to omit various sensors related to the error elimination processing of the toner consumption amount, and the cost of the entire image forming apparatus can be reduced. Even if the error elimination processing is performed, the processing time is shortened, and the processing performance of the entire image forming apparatus can be improved.

1 is a diagram schematically showing a configuration of a scanning optical system of an image forming apparatus according to an embodiment of the present invention. It is a figure which shows the structure of the video count calculating part in FIG. 1 in the process order of image data. FIGS. 3A and 3B are diagrams illustrating weighting processed by the video count calculation unit in FIG. 2. FIG. 3A illustrates an example of weighting calculated by a weighted prediction calculation unit, and FIG. (C) shows the deleted image data line memory area. It is a figure which shows the example of weighting when an isolated point pixel exists. It is a figure which shows the example which changes a weighting value with position data. It is a figure which shows the overlap of the laser spot in a 3x3 pixel row | line | column. It is a figure which shows the laser spot of the isolated point pixel in a 3x3 pixel row | line. It is a figure which shows the example of the image data in which an isolated point pixel exists. It is a figure which shows the example which changes a laser spot position with position data.

Explanation of symbols

101 Laser 104 Image Data Line Memory 105 Video Count Calculation Unit 201 Weighting Calculation Unit 203 Cumulative Addition Calculation Unit 204 Video Count Prediction Calculation Unit

Claims (3)

In an image forming apparatus including an image data line memory and a video count prediction calculation unit,
The video count calculation unit performs weighting calculation on a plurality of peripheral pixels centered on the target pixel according to at least one of the density of the target image, the distance from the target pixel, and the position with respect to the target pixel. A weighted prediction calculation unit, a cumulative addition calculation unit that cumulatively adds video count values before the target pixel as the weighting calculation result for the same main scanning direction, the updated image data in the image data line memory, and the cumulative An image forming apparatus, comprising: a video count prediction calculation unit that predicts and calculates a toner consumption amount of a target pixel using an addition result.   The image forming apparatus according to claim 1, wherein the weighting calculation unit includes a lookup table.   3. The image forming apparatus according to claim 2, wherein the look-up table defines a weight value corresponding to at least one of a density of the target image, a distance from the target pixel, and a position with respect to the target pixel. .

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