JP2018055025A - Image forming apparatus and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of accurately calculating an output image density in comparison with one for optically detecting a toner pattern image having a different area ratio and calculating an output image density of 100% from the detected different area ratio output value and to provide a program.SOLUTION: The image forming apparatus includes toner pattern forming means for forming a toner pattern image having a predetermined pixel density on an image holder, acquisition means for optically detecting the toner pattern image formed by the toner pattern forming means and acquiring the output value, toner amount calculation means for comparing the output value acquired by the acquisition means with a predetermined target value and calculating a toner amount of a pixel density of 100%, and output pixel density calculation means for calculating an output pixel density corresponding to an input pixel density of 100% on the basis of the toner amount calculated from the toner amount calculation means.SELECTED DRAWING: Figure 4

Description

  The present invention relates to an image forming apparatus and a program.

  Patent Document 1 is a method for creating a correction table for correcting recording characteristics of a recording apparatus having nonlinear characteristics between an input signal value and a recording signal value output in accordance with the input signal value, Correspondence table of input signal value and recording density obtained by recording an image for density measurement in a state where the nonlinear characteristic is compensated, measuring the density of the image for density measurement, and obtained based on the measured density An intermediate gradation correction table is created by reverse-conversion, and a conversion method is performed on the intermediate gradation correction table in consideration of the nonlinear characteristics.

JP 2004-149292 A

  The present invention optically detects toner pattern images having different area ratios, and calculates the output image density with higher accuracy than that for calculating the output image density of 100% from the detected output values of the different area ratios. An object of the present invention is to provide an image forming apparatus and a program that can be used.

  According to the first aspect of the present invention, a toner pattern forming unit that forms a toner pattern image having a predetermined pixel density on an image holding member, and a toner pattern image formed by the toner pattern forming unit is optically detected. Obtaining means for obtaining an output value, comparing the output value obtained by the obtaining means with a predetermined target value to calculate a toner amount having a pixel density of 100%, and the toner An output pixel density calculating unit that calculates an output pixel density corresponding to an input pixel density of 100% based on the toner amount calculated from the amount calculating unit.

  According to a second aspect of the present invention, the acquisition unit includes an optical sensor having a light emitting element and a light receiving element, and light emitted from the light emitting element of the optical sensor is irradiated onto the toner pattern image, whereby the toner pattern image is obtained. The image forming apparatus according to claim 1, wherein light amount data obtained by receiving reflected light at a light receiving element of the optical sensor is acquired.

  According to a third aspect of the present invention, in the image forming apparatus according to the first or second aspect, the toner amount calculating unit calculates a toner amount having a pixel density of 100% by linear calculation.

  The present invention according to claim 4 is the image generating apparatus according to claim 1 or 2, wherein the output pixel density calculating means calculates the output pixel density by linear calculation.

  According to a fifth aspect of the present invention, the toner pattern forming unit forms a toner pattern image having a pixel density lower than 100%, and the toner amount calculating unit stores in advance the output value acquired by the acquiring unit. 5. The image forming apparatus according to claim 1, wherein a toner amount having a pixel density of 100% is calculated based on the linear relationship.

  According to a sixth aspect of the present invention, a step of forming a toner pattern image having a predetermined pixel density on the image holding member, a step of optically detecting the formed toner pattern image and acquiring an output value, A step of calculating a toner amount having a pixel density of 100% by comparing the acquired output value with a predetermined target value, and an output pixel corresponding to the input pixel density of 100% based on the calculated toner amount A program for causing a computer to execute a step of calculating a density.

  According to the first aspect of the present invention, a toner pattern image having a different area ratio is optically detected, and compared with an apparatus that calculates 100% output image density from the detected output values of different area ratios. It is possible to provide an image forming apparatus capable of calculating the output image density with high accuracy.

  According to the second aspect of the present invention, in addition to the effect of the first aspect of the present invention, the output value can be acquired from the amount of reflected light with respect to the toner pattern.

  According to the third aspect of the present invention, in addition to the effect of the first or second aspect, the toner amount with a pixel density of 100% can be calculated by a simple calculation.

  According to the present invention of claim 4, in addition to the effect of the invention of claim 1 or 2, the output pixel density can be calculated by a simple calculation.

  According to the present invention of claim 5, in addition to the effect of the invention of any of claims 1 to 4, the sensitivity of light amount detection is improved compared to the case of forming a toner pattern having a pixel density of 100%. Can be bigger.

  According to the present invention of claim 6, compared to a case where a toner pattern image having a different area ratio is optically detected and an output image density of 100% is calculated from the detected output values of the different area ratios, A program capable of calculating the output image density with high accuracy can be provided.

1 is a side sectional view showing an image forming apparatus according to an embodiment of the present invention. It is a side view of the optical sensor used for the embodiment of the present invention. FIG. 3 is a block diagram illustrating a control unit of the image forming apparatus according to the embodiment of the present invention. 4 is a flowchart illustrating an operation flow of a control unit of the image forming apparatus according to the embodiment of the present invention. In embodiment of this invention, it is a diagram which shows the relationship of the detected value (RADC) of the test patch with respect to the input area ratio Cin. In the embodiment of the present invention, it is a diagram showing the relationship of the detection value (RADC) of the test patch with respect to the toner amount for each input area ratio Cin. In embodiment of this invention, it is a diagram which shows the relationship with (DELTA) TMA with respect to (DELTA) RADC. In embodiment of this invention, it is a diagram which shows the relationship between linear Cin and TMA. 5 is a flowchart showing an operation flow when actually outputting in the embodiment of the present invention. It is a flowchart which shows the operation | movement flow in a comparative example. It is a diagram for calculating Cout in a comparative example.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  The image forming apparatus 10 includes a paper feeding device 14 below the image forming apparatus main body 12. The paper feeding device 14 includes a recording medium storage unit 16, and a large number of recording media are stored in the recording medium storage unit 16. The recording medium accommodation unit 16 is provided with a delivery roll 20 that sends out the uppermost recording medium contained in the conveyance path 18.

  The conveyance path 18 is a conveyance path from the recording medium storage unit 16 to the recording medium discharge port 21, and is provided with a conveyance roll 22 and a registration roll 24.

  On the upper portion of the image forming apparatus main body 12, four laser writing devices 26 for each color of YMCK are provided. Further, a photosensitive member 28 as an image holding member is disposed below each laser writing device 26. Around the photoconductor 28, a charger 30, a developing device 32, a primary transfer roll 34, and a cleaning device 36 are arranged. A latent image is formed on the photosensitive member 32 charged by the charger 30 by the laser from the laser writing device 26, the latent image is developed by the developing device 32, and the developed toner image is transferred by the primary transfer roll 34. It is transferred to an intermediate transfer member 38 to be described later. The toner remaining on the photoreceptor 28 is scraped off by the cleaner 36.

  An intermediate transfer member 38 that is an image carrier is supported by a primary transfer roll 34, a backup roll 40, and a plurality of support rolls 42. The primary transfer roll 34 faces the photoconductor 28 with the intermediate transfer body 38 interposed therebetween. The backup roll 40 faces the secondary transfer roll 44 with the intermediate transfer member 38 interposed therebetween. The toner image transferred to the intermediate transfer member 38 by the primary transfer roll 34 is transferred to the recording medium conveyed via the conveyance path 20 by the secondary transfer roll 44.

  The conveyance path 20 supplies a recording medium between the backup roll 40 and the secondary transfer roll 44 and further supplies the recording medium to the fixing device 46. A conveyance belt 48 is provided between the secondary transfer roll 44 and the fixing device 46.

  The fixing device 46 includes a heating roll 50 and a pressure roll 52, and fixes the toner image transferred to the recording medium to the recording medium by heat and pressure. The recording medium on which the toner image is fixed by the fixing device 48 is discharged from the recording medium discharge port 21 to the recording medium discharge portion 54.

  In this embodiment, the optical sensor 56 is provided opposite to the intermediate transfer member 40 on the downstream side of the K-color photoconductor 30 disposed on the last flow side. The optical sensor 56 detects the amount of light corresponding to the amount of toner from the toner pattern image of each color of YMCK.

In FIG. 2, details of the optical sensor 56 are shown. The optical sensor 56 includes a light emitting element 58 and a light receiving element 60. The light emitting element 58 is, for example, an LED, and emits light toward a patch 62 constituting a toner pattern image formed on the intermediate transfer body 40. The light receiving element 60 is a photodiode, for example, and receives light reflected from the toner pattern image 62. The toner pattern image is formed in a portion where no image is formed. The optical sensor 56 may detect the amount of light in a portion where the toner pattern image is not formed.
In this embodiment, the toner pattern image is formed on the intermediate transfer member 38. However, the toner pattern image is formed on the photosensitive member 28, and the amount of reflected light of the toner pattern image on the photosensitive member 28 is detected. Anyway.

FIG. 2 shows a hardware configuration of the control unit 64 in the image forming apparatus 10.
The control unit 64 includes a CPU 66, a memory 68, an input interface 70, and an output interface 72, which are connected via a control bus 74.

  The CPU 66 executes a predetermined process based on a control program stored in the memory 68. The optical sensor 56 described above is connected to the input interface 70. The output interface 72 is connected to a toner concentration adjusting unit 76 that adjusts the toner concentration. The toner density adjusting unit 76 adjusts the toner density by adjusting the laser output of the laser writing device 28 or adjusting the bias voltage of the developing unit 34, for example. The CPU 66 acquires the light amount of the toner pattern image output from the optical sensor 56, and outputs a control signal to the toner concentration adjusting unit 76 according to a program described later to control the toner concentration.

Next, a processing flow by the CPU 66 will be described.
FIG. 3 is a flowchart of a program executed by the CPU 66.

First, in step S10, it is determined whether or not a density adjustment execution flag is set.
Density adjustment (setup) is a factor of fluctuations in image density, such as the cumulative number of sheets traveled since the previous setup, rapid changes in temperature and humidity, replacement of the image carrier (photoreceptor / intermediate transfer member), and replacement of the developer (developer). An execution flag is set by detecting.

  If it is determined in step S10 that the density adjustment execution flag is not set, the process is terminated. On the other hand, if it is determined in step S10 that the density adjustment execution flag is set, the process proceeds to the next step S12.

  In the next step S12, in response to the setup being performed, light is emitted from the optical sensor facing the image carrier to a portion where no image is formed, and the reflected light output (hereinafter referred to as V clean) is detected. .

  In the next step S14, a patch (for example, Cin 90%) having a high input area ratio (hereinafter, Cin) is formed on the image holding member (for example, intermediate transfer member) with toner under predetermined image forming conditions.

  In the next step S16, the patch is irradiated with light from the optical sensor facing the image carrier, and the reflected light output (hereinafter referred to as V patch) is detected.

In the next step S18, the patch detection value (hereinafter referred to as RADC) is calculated by normalizing V patch with V clean (V patch / V clean).
That is, the current RADC is calculated by the following equation (1).
Current RACD_90% = Vpatt / Vclean (1)

Here, the reason why the patch is not Cin 100% is as follows.
As shown in FIG. 5, when a toner pattern image is detected with a specular component like an image carrier, the sensitivity is mainly in the toner coverage, so the sensitivity is high on the low Cin side and low on the high Cin side. Therefore, sensitivity is saturated at high Cin. Therefore, as shown in FIG. 5, the sensor output sensitivity to Cin is nonlinear. On the other hand, if the deviation from Cin100% is large, an error is likely to occur in the relationship between the density of detected Cin and Cin100%. For example, Cin90% is assumed, and the value of Cin100% is predicted from the output value in the case of Cin90%.

  On the other hand, when the toner amount increases or decreases with respect to one Cin, the coverage does not change and the toner height (pile height) increases or decreases. Therefore, as shown in FIG. 6, the relationship of the RADC with respect to the toner amount TMA is linear. FIG. 6 shows an actual measurement of RADC by increasing or decreasing the amount of toner that would be Cin 100% due to environmental changes or the like in each case of 90%, 95%, and 100% as one Cin. In either case, TMA changes linearly with changes in RADC. Such a change in TMA with respect to a change in RADC is stored in the memory described above.

In the next step S20, the difference between the current RADC and the target RADC is obtained as ΔRADC as shown in the following equation (2).
ΔRADC_90% = target RACD_90% −current RACD_90% (2)

In the next step 22, assuming that the difference between the currently predicted 100% TMA and the target TMA is ΔTMA, ΔRADC and ΔTMA are in a linear relationship as shown in FIG. 7, and therefore ΔTMA is multiplied by a coefficient. calculate. That is, ΔTMA is calculated by the following equation (3).
ΔTMA = ΔRADC — 90% × coefficient (3)

In the next step S24, ΔTMA is added to the target TMA to calculate the current TMA. That is, the current TMA is calculated by the following equation (4).
Current TMA = Target TMA + ΔTMA (4)

In the next step S26, linear Cout_100% is obtained. That is, as shown in FIG. 8, since linear Cin and TMA are in a linear relationship, linear Cout is calculated by the following equation (5) from the relationship between the current TMA and the target TMA.
Linear Cout_100% = target TMA / current TMA × 100 (5)

  As described above, Cout_100% can be obtained by linear calculation by replacing RACD with a shared TMA.

  When the image is formed, the process proceeds to the flowchart shown in FIG. 9. If it is determined in step S30 that the screen of the image is linear, the process proceeds to step S32, and linear Cout is applied to the 100% density portion. If it is determined that it is not, the process proceeds to step S34, where the linear Cout is converted in accordance with the screen, and the converted Cout is applied to the 100% density portion.

FIG. 10 shows a flowchart in the comparative example.
The processing in steps S40 and S42 is the same as that in the above-described embodiment.

  In this comparative example, a different RADC is calculated from different Cin patches to calculate a target RADC_100%.

  That is, in step S44, a plurality of patches having different Cin (for example, Cin 90% and Cin 100%) are formed on the image holding member under predetermined image forming conditions. In step S46, each patch from the optical sensor is irradiated with light, and the V patch is detected. In the next step S48, RADC is calculated by normalizing V patch with V clean (V patch / V clean). In step S50, Cout as a target RADC is calculated from the relationship between each Cin and RADC. At this time, Cin and RADC are treated as a linear relationship. However, since the actual relationship is not a straight line as shown in FIG. 11, an error occurs when calculating Cout. When an error occurs, for example, the amount of toner becomes larger than the target, and image defects such as transfer failure and fixing failure may occur.

  In contrast to such a comparative example, in the above-described embodiment, Cout_100% is obtained by linear calculation by replacing RACD with a shared TMA so that an error as in the comparative example does not occur.

  In the above-described embodiment, the toner pattern image is composed of one patch having a predetermined input area ratio. However, the toner pattern image is composed of a plurality of patches having different input area ratios. May be obtained, and the respective values may be averaged.

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 28 Photoconductor 38 Intermediate transfer body 56 Optical sensor 58 Light emitting element 60 Light receiving element 62 Patch 64 Control part 66 CPU
68 memory

Claims (6)

Toner pattern forming means for forming a toner pattern image having a predetermined pixel density on the image carrier;
Obtaining means for optically detecting a toner pattern image formed by the toner pattern forming means to obtain an output value;
A toner amount calculating means for calculating a toner amount having a pixel density of 100% by comparing the output value acquired by the acquiring means with a predetermined target value;
Output pixel density calculating means for calculating an output pixel density corresponding to an input pixel density of 100% based on the toner amount calculated from the toner amount calculating means;
An image forming apparatus.   The acquisition unit includes an optical sensor having a light emitting element and a light receiving element, and the light emitted from the light emitting element of the optical sensor is applied to the toner pattern image, and the light reflected on the toner pattern image is received by the optical sensor. The image forming apparatus according to claim 1, wherein the light amount data received by the element is acquired.   The image forming apparatus according to claim 1, wherein the toner amount calculation unit calculates a toner amount having a pixel density of 100% by linear calculation.   The image generation apparatus according to claim 1, wherein the output pixel density calculation unit calculates the output pixel density by linear calculation.   The toner pattern forming unit forms a toner pattern image having a pixel density lower than 100%, and the toner amount calculating unit calculates the output value acquired by the acquiring unit based on a linear relationship stored in advance. The image forming apparatus according to claim 1, wherein a toner amount having a density of 100% is calculated. Forming a toner pattern image having a predetermined pixel density on the image carrier;
Optically detecting the formed toner pattern image to obtain an output value;
Comparing the acquired output value with a predetermined target value to calculate a toner amount having a pixel density of 100%;
Calculating an output pixel density corresponding to an input pixel density of 100% based on the calculated toner amount;
A program that causes a computer to execute.

Images