JP2004264765A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of surely performing operation to replenish a toner. <P>SOLUTION: The image forming apparatus for printing paper with image data a by supplying the toner to a developing device 13 by driving section 14 for toner replenishment is equipped with a pixel counter 3 which has a conversion table 2 for converting the density of the image data to be printed to the amount of consumption of the toner and counts the number of pixels or the converted amount of consumption of the toner, and a comparator circuit 6 which can occasionally read out the count value of the pixel counter 3 and outputs a compared coincidence signal when the counter value attains a preset value such that the operation to replenish the toner can be performed in accordance with the output of the comparator circuit 5. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image forming apparatus that prints image data on recording paper using a recording agent such as toner.
[0002]
[Prior art]
Conventionally, as an image forming apparatus used in an MFP (combined printing apparatus of a copier + printer + fax machine), for example, an image forming apparatus without the comparison circuit 5 in FIG. 1 has been known. The scanner unit 9 includes a scanner unit 9 that reads an image of a document and outputs an image signal, and a system controller 10 that receives an image signal obtained by the canner unit 9 and controls an engine controller described below. . The engine control unit receives an image signal from the system control unit 10 and outputs image data. An image processing unit 1 receives the image data from the image processing unit 1 and converts the image data into a density conversion LUT (lookup table). 2, a pixel counter 3 for counting the density signal obtained by the density conversion LUT 2, a register CPU I / F 4 for temporarily storing the count value of the pixel counter 3, a CPU 6 for controlling the entire control, a memory ROM 7, And a RAM 8. The whole except for the CPU 6, the memory ROM 7, and the memory RAM 8 is constituted by an engine image processing ASIC (integrated circuit for special use).
[0003]
Further, a laser driver (laser exposure control unit) 11 for inputting image data from the image processing unit 1 and controlling a laser light amount to be given to the photosensitive drum 12, and a developing device arranged to face the outer peripheral surface of the photosensitive drum 12 13 is provided with a toner replenishing unit 14 for replenishing toner.
[0004]
In the conventional image forming apparatus configured as described above, the CPU 6 reads the value of the pixel counter 3 every time printing of a predetermined page is completed, as shown in FIG. 2, and replenishes toner according to the consumption amount. Was.
[0005]
Such an image forming apparatus that calculates the amount of consumption for each page includes a relatively large developing unit so that toner does not run out in the middle of a page, and there is no problem in performing continuous printing. It has become.
[0006]
However, in recent image forming apparatuses, there has been a demand for a reduction in the size of the apparatus, and accordingly, a developing device for storing toner has also become smaller, and the amount of stored toner tends to decrease.
[0007]
Therefore, in the conventional control method, there is a possibility that the toner may run short in the middle of the page. Therefore, it is conceivable that the toner consumption is calculated and replenished in the middle of the page. Is performed asynchronously, so that if reading is performed during counting, an accurate value may not be read at a certain timing, for example, when the CPU is executing another process. Further, the read operation required a certain amount of time.
[0008]
2. Description of the Related Art Conventionally, as an example of this type of image forming apparatus, there is the following known example (see Patent Document 1). This includes counting the frequency of each density level from the image data of the document, counting means for counting the frequency, and toner consumption calculating means for calculating the amount of toner consumed in the developing device from the cumulative value of the multiplication result for each density level, There is a device having a unit for replenishing toner to the developing device based on the obtained toner consumption amount, which is configured to accurately predict the toner consumption amount from image data and perform toner replenishment control ( Patent Document 1).
[0009]
[Patent Document 1]
Japanese Patent Application Laid-Open No. 8-146736
[Problems to be solved by the invention]
In the case of the above-described conventional image forming apparatus, when the consumption amount of toner is estimated using the pixel counter 5 during printing of a page, and is applied to the control of toner replenishment, an accurate value is read at a certain timing. In some cases, the reading operation cannot be performed, and a certain amount of time is required for the reading operation. Therefore, a problem such as insufficient toner supply or excessive replenishment may occur.
[0011]
The present invention has been made to solve such a problem, and an object of the present invention is to provide an image forming apparatus capable of reliably performing a supply operation of a recording material such as toner.
[0012]
[Means for Solving the Problems]
In order to achieve the above object, an image forming apparatus that supplies a recording material to a developing device by a recording material replenishment drive unit and prints image data on a sheet is provided by the invention according to claim 1. Counting means for counting the number of pixels or the converted printing material consumption amount, which has a conversion table for converting the printing material consumption amount into
A comparing unit that can read a count value of the counting unit at any time, and outputs a comparison coincidence signal when the counter value reaches a preset value;
An image forming apparatus is configured such that a replenishing operation of the recording material can be performed based on an output of the comparing unit.
[0013]
To achieve the above object, the invention corresponding to claim 2 is as follows. 2. The image forming apparatus according to claim 1, wherein when the recording material supply drive unit is controlled by a computer, the computer performs an interrupt process when a comparison match signal is generated from the comparison unit.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram for explaining the outline of the present invention. In the following description, a toner will be described as an example of a recording agent, but the recording agent is not limited to the toner, and may be an ink.
[0015]
The image data read by the scanner unit 9 is input to the image processing unit 1 via the system control unit 10. The image processing unit 1 performs a smoothing process for adjusting image quality and a γ correction process on the input image data a to generate print data. The print data is output to a laser exposure control unit (LSU) 11 and, at the same time, sent to a density conversion LUT (look-up table) 2. The density conversion LUT 2 includes a conversion table for converting image data to be printed into a toner consumption amount, generates data indicating the toner density based on the print data, and consumes the data when the pixel counter 3 actually prints. The amount of toner is counted and output to the comparison circuit 5. The pixel counter 3 counts the number of pixels or the converted toner consumption.
[0016]
The comparison circuit 5 supplies to the CPU 6 a mechanism capable of reading out the count value of the pixel counter 3 and a comparison match signal c whose count value matches a preset value s.
[0017]
The image processing unit 1, the density conversion LUT 2, and the comparison circuit 5 are connected to a register CPU I / F 4, and various setting values required for the operation and the setting value s compared by the comparator 5 are transmitted via the CPU I / F 4. Each is set from the CPU 6.
[0018]
The CPU 6 also controls the entire printer unit. The CPU 6 is connected to a memory ROM 7 in which a control program and the like are stored, and a data storage memory RAM 8.
[0019]
The CPU 6 controls the printing operation based on the data in the ROM 7 and the RAM 8, and supplies a toner supply signal to the toner supply drive unit 14 as an interrupt signal of the CPU, thereby performing toner supply control. The laser light output from the laser exposure control unit 11 is applied to the outer peripheral surface of the photosensitive drum 12, and the toner supply driving unit 14 supplies toner to the developing device 13 based on a toner supply signal from the CPU 6. The toner is visualized on the outer peripheral surface of the photosensitive drum 12 which is disposed to face the developing device 13 and is configured to be rotatable.
[0020]
According to the above-described embodiment of the present invention, since the comparison circuit 5 having, for example, an H / W configuration is added between the pixel counter 3, the CPU 6, and the register CPU I / F 4, a reliable toner supply operation can be performed. realizable. In this case, the comparison circuit 5 compares the counter value of the pixel counter 3 with a preset value s, and outputs a comparison match signal c to the CPU 6 when they match. Since the comparison coincidence signal c output from the comparison circuit 5 is an interrupt signal input to the CPU 6, the toner is reliably and timely supplied, and the value of the pixel counter 3 reaches a target value. You will be able to know that. As a result, when a problem that occurred in one example of the conventional image forming apparatus, that is, the toner consumption during printing is estimated using a pixel counter and applied to toner replenishment control, toner supply shortage or excessive toner supply occurs. The problem of resupply does not occur.
[0021]
According to the embodiment described above, it is possible to clarify the correlation between the consumption amount of the recording material, for example, the toner, and the pixel counter 3. Specifically, the image data and the toner actually consumed are corrected using the density conversion LUT 2. In this case, it is determined how much (consumption) and how much toner should be supplied during printing of the page. The setting value s of the comparison circuit 5 is set based on the above result. In this case, as shown in FIG. 2, when the count value of the pixel counter 3 reaches the set value s, the comparison circuit 5 outputs the comparison coincidence signal c. When the comparison match signal c is detected by the CPU 6, the supply of a predetermined amount of toner is started. This operation is repeated in one-color printing units.
[0022]
The present invention is not limited to the embodiments described above, and can be implemented with various modifications. In the above-described embodiment, the case where the number of the comparison coincidence signals c output from the comparison circuit 5 is one has been described. May be output.
[0023]
【The invention's effect】
According to the present invention described above, it is possible to provide an image forming apparatus capable of reliably performing a supply operation of a recording agent such as a toner.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a schematic configuration of an embodiment of an image forming apparatus according to the present invention.
FIG. 2 is a timing chart for explaining the access timing of the CPU of FIG. 1 and the function of the comparison circuit.
[Explanation of symbols]
a ... image data, s ... set value, c ... comparison signal, 1 ... image processing unit, 2 ... density conversion LUT, 3 ... pixel counter, 4 ... register, 5 ... comparison circuit, 6 ... CPU, 7 ... memory ROM 8 Memory RAM 9 Scanner unit 10 System control unit 11 Laser exposure control unit 12 Photosensitive drum 13 Developing unit 14 Toner supply driving unit

Claims (2)

In an image forming apparatus that supplies a recording agent by a recording agent supply driving unit to a developing device and prints image data on paper,
Counting means having a conversion table for converting the density of the image data to be printed into the consumption of the recording material, and counting the number of pixels or the converted consumption of the recording material,
A comparing unit that can read a count value of the counting unit at any time, and outputs a comparison coincidence signal when the counter value reaches a preset value;
The image forming apparatus according to claim 1, wherein a replenishing operation of the recording material can be performed based on an output of the comparing unit. 2. The image forming apparatus according to claim 1, wherein when the recording material supply drive unit is controlled by a computer, the computer performs an interrupt process when a comparison coincidence signal is generated from the comparison unit. .

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