JP3406507B2 - Image forming method and image forming apparatus - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming method and an image forming apparatus such as a copying machine, a facsimile, a printer, etc., and in particular, it measures the surface shape of a sheet and determines the most suitable color developing particles for the sheet. The present invention relates to an image forming method and an image forming apparatus capable of obtaining a good image by supplying the image.

[0002]

2. Description of the Related Art Generally, there are various types of paper,
Largely classified, coated printing paper such as art paper and coated paper,
Non-coated paper such as high-quality paper, medium-quality paper and lower-grade paper, generally copiers,
OA (PPC: Plain P) used for printers
There is an information sheet called an "aper Copy" sheet. Further, among PPC papers, the surface properties, paper thicknesses, etc. differ depending on the paper manufacturer, and even when similar image formation is performed, there is a considerable difference in the image formation quality depending on the paper. This is because the shape of the fibers forming the paper and the manufacturing process are different, so the degree of unevenness of the paper is different. When a paper having a large unevenness is used, the powder toner particles formed on the paper at the time of image formation penetrate more into the concave portion and penetrate deeply, and the background of the paper is visible when the toner amount is small. On the other hand, on paper with good surface smoothness, toner particles do not penetrate deeply and the amount of toner may be small. Conversely, if the amount of toner is large, the toner will spill out to areas other than those required for image formation, and the edges of the image will not appear. No longer sharp. Therefore, in order to form a high quality image, it is necessary to form an image according to the surface shape of the paper.

Conventionally, as a recording medium used in an image forming apparatus such as a copying machine, a facsimile or a printer, a standard sheet is determined as a measure against the surface roughness or the thickness, and it is suitable for this. As described above, the image forming conditions in the apparatus are generally fixed. However, in this case, since the usable paper is fixed, it is inconvenient for the user to use it.

Therefore, in order to solve this problem, the thickness and type of the recording medium are detected, and the temperature and pressure of the fixing unit in the electrophotographic apparatus are adjusted according to the detected thickness and type to form an image. A device for performing the operation is disclosed in JP-A-4-31516.
No. 2, JP-A-4-315188, JP-A-5-
It is disclosed and proposed in Japanese Patent No. 297763.

1) In Japanese Patent Laid-Open No. 4-315162,
The surface smoothness of the paper is measured by the paper smoothness measuring member. Based on the obtained measurement result, if the smoothness is not smooth, the smoothing processing member performs the smoothing process and then the image formation is performed. Here, as the paper smoothness measuring member, JIS
An improved version of the Gurley densometer specified in Section 1 is used, which sandwiches the paper between the upper and lower pressure contact bodies, pushes out the air inside the cylinder at a constant pressure, and measures the time for air to leak from the gap. It is a thing. Further, as the smoothing processing member, a heat roller and a pressure roller of the fixing processing section are used, and the paper is once sandwiched and passed before image formation to reduce unevenness on the surface of the paper and smooth the paper.

2) In Japanese Patent Laid-Open No. 4-315188,
The configuration and function of the paper smoothness measuring member are the same as those in 1) above, but instead of using the smoothing processing member, the fixing condition at the time of the fixing process is based on the measurement result obtained by the paper smoothness measuring member. An image is formed by controlling the. Here, the fixing conditions include the heating temperature of the heat roller, the pressure of the heat roller and the pressure roller, the rotation speed, and the like.

3) In Japanese Patent Laid-Open No. 5-297763,
An image is formed by detecting the amount of light transmission of the recording medium with a photosensor, detecting and identifying the thickness and type of the recording medium, and controlling the fixing conditions during the fixing process based on the detection result. Here, the fixing conditions include the heating temperature of the fixing roller, the pressure of the pressure roller in the fixing nip portion, and the like.

[0008]

However, the above-mentioned image forming apparatus has the following problems.

In the above 1) and 2), there is a problem that the structure of the paper smoothness measuring member which is an improvement of the Gurley densometer, which is a device for measuring the surface shape, is complicated, and the measuring time is long. . Further, there is also a problem that it takes time to heat or cool to a predetermined temperature due to temperature control during fixing.

In the above 3), in the disclosed detection method, the thickness and type of the recording medium (whether it is paper or OHP).
Can be detected, but unevenness on the surface of the paper cannot be detected, and it is difficult to form an image suitable for various types of paper.

The present invention has been made in order to solve the above problems, and its purpose depends on various types of image forming sheets, that is, the types and surface roughness of recording media used. To provide a high-quality and high-quality image forming method and an image forming apparatus without any problems. further,
It is an object of the present invention to provide a smoothness detector capable of detecting the smoothness of the recording medium with high accuracy.

[0012]

An image forming method according to a first aspect of the present invention comprises a charging step of charging a surface of a photoconductor, and an exposure step of exposing the charged surface of the photoconductor to form an electrostatic latent image. In an image forming method, a surface state of a recording medium, including a step, a developing step of developing an electrostatic latent image on the surface of the photoconductor to form a toner image, and a transfer step of transferring the toner image onto a recording medium. Two-dimensional image representing
Based on the fractal dimension information calculated from the information, the serial
The recording medium has an amount of toner that is almost proportional to the fractal dimension information.
The image forming parameter for forming the electrostatic latent image or the toner image is controlled so as to supply the image.

The image forming method according to claim 2 of the present invention is
The image forming method according to claim 1, wherein the image forming parameter is an irradiation light intensity for forming an electrostatic latent image on the photoconductor.

The image forming method according to claim 3 of the present invention comprises:
The image forming method according to claim 1, wherein the image forming parameter is a charging initial potential for forming an electrostatic latent image on the photoconductor.

The image forming method according to claim 4 of the present invention is
In the image forming method according to the present invention, the image forming parameter is a developing bias for forming a toner image on the photoconductor.

The image forming apparatus according to claim 5 of the present invention is
A photoconductor, a charging unit that charges the surface of the photoconductor, an exposure unit that exposes the charged surface of the photoconductor to form an electrostatic latent image, and a toner that develops the electrostatic latent image on the surface of the photoconductor. An image forming unit including a developing unit that forms an image and a transfer unit that transfers the toner image onto a recording medium, a smoothness detecting unit that measures and detects the smoothness of the recording medium, and an image based on the detection result. In an image forming apparatus including image forming control means for controlling formation, the smoothness detecting means includes a light emitting means for irradiating a recording medium with light, and a two- dimensional image of intensity distribution of reflected light from the recording medium. The image forming control means has an information detecting means for detecting as information and an information processing means for performing an operation on the two- dimensional image information from the information detecting means and converting it into fractal dimension information which is one-dimensional information. , The above 1 Substantially proportional to the fractal dimension information recording medium based on fractal dimension information is source information
Control the image forming parameters for forming the electrostatic latent image or the toner image so as to supply the toner of a predetermined amount,
It is characterized by

[0017]

[0018]

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, will be explained with reference to the drawings and tables with the image forming method and image forming equipment according to the present invention.

First, the basic principle of the smoothness detector of the recording medium used in the image forming method and the image forming apparatus of the present invention will be described.

FIG. 1 shows a basic block configuration relating to the smoothness detector, and FIG. 2 shows a basic processing sequence thereof.

The light emitting means 101 including the semiconductor laser 18 and the lens 18a illuminates the surface of the recording medium 1 with the light 2a (step S2-1). In that case, the irradiation area is appropriately in the range of φ1 to φ10 mm. Then, the information detecting means 102 including the image reading means 19 reads the shadow image formed by the reflected light 2b of the area irradiation as a plane image, and detects the grayscale information as multi-valued image data (step S2-2). . That is, the irradiated light 2a is shaded on the reflected light 2b due to the unevenness of the recording medium 1, the concave portion is dark and the convex portion is bright, and this shadow image is detected by the CCD 19 of the image reading means. Here, the image reading unit 19 is a CCD (Charge Co).
However, the present invention is not limited to this. The information processing unit 103 performs image processing on the grayscale information, which is the multivalued image data detected above, to measure and calculate the surface roughness of the recording medium 1 (step S2-3). Thereafter, the image forming parameter value corresponding to the measured and calculated surface roughness is set to the image forming control means 10.
4 to determine and control (step S2-4).

Generally, the relationship between optical density and surface roughness is
If the materials are the same, the larger the surface roughness, the smaller the reflected light from the material, and the smoother the surface, the larger the reflected light from the material. Here, FIG. 3 shows the output voltage from the CCD 19 and the density of the reflected light for one pixel of the image read by the CCD 19. Therefore, C
The surface roughness of the recording medium can be inferred by reading the grayscale information from the CD 19.

For example, the concentration level obtained above is set to 25
It is quantized into 6 values and converted into an image having a density level of 256 gradations. If the average height difference from the average height of all pixels in the measurement range is taken as the center line average roughness (Ra), it is

[0025]

[Equation 1]

It is represented by Here, N is the total number of pixels in the measurement range.

Table 1 shows the difference in surface roughness as a result of the measurement when plain paper is used as the recording medium 1 in this way.

[0028]

[Table 1]

Generally, the printing state has a great influence on the surface roughness of the recording medium.

In the above description, the surface roughness was indicated by the center line average roughness (Ra), but the same applies to the ten-point average roughness (Rz) and the maximum surface roughness (Rmax) as shown in Table 1. Can be obtained. In other words, in a recording medium having a high surface roughness, the toner enters the concave portion of the recording medium, and therefore,
When the amount of toner is small, the fibers of the recording medium are exposed on the surface, and a good image cannot be formed. Further, in a recording medium having a low surface roughness, the edges of characters and images do not become sharp when the amount of toner is large.

From the above, a good image can be obtained by reducing the toner amount (developing particle amount) for a recording medium having a small surface roughness and increasing the toner amount for a recording medium having a large surface roughness. I found that I could be.

Next, a method for measuring and calculating the surface roughness of the recording medium by subjecting the grayscale information, which is multi-valued image data, to image processing by the information processing means 103 will be described.

FIG. 4 shows the fractal dimension of step S2-3 of FIG. 2 in which the surface roughness of the recording medium is measured and calculated by performing image processing on the grayscale information, which is multivalued image data, by the processing means 103. 3 shows a processing sequence when is used. The basic structure and function of the apparatus are the same as those in FIG.

Step S4-1) The light emitting means 101 irradiates the surface of the recording medium 1 with the light 2a.

Step S4-2) The information detecting means 102 reads the shadow image formed by the reflected light 2b for area irradiation as a plane image, and detects the grayscale information as multivalued image data. In other words, the density level of the grayscale information read by the CCD 19 is quantized into 256 values and converted into an image having a density level of 256 gradations.

Step S4-3) The gradation information, which is the multi-valued image data detected above, that is, an image having a density level of 256 gradations here, is recorded by performing image processing by the information processing means 103. The surface roughness of the medium 1 is calculated by the fractal dimension. This process is composed of the following four steps.

Step S4-3-1) The above step S4
-2, a black and white binary image is formed with a certain threshold value for the image having the density level of 256 gradations.

Step S4-3-2) When forming the monochrome binary image, the number of black pixels in the monochrome binary image is counted.

Step S4-3-3) After that, the number of black pixels is visualized, and a monochrome binary image is formed in the same manner as above.

Step S4-3-4) The above step S4
3-1 to step S4-3-3 are repeated, and the fractal dimension is determined using the count value of the number of black pixels.

Step S4-4) Thereafter, the image forming control means 104 determines and controls the image forming parameter value corresponding to the calculated fractal dimension.

Here, a certain threshold Th in step S4-3-1 is determined by the following equation.

Th = minimum density + (maximum density-minimum density) × median density / 256 ... The maximum density and the minimum density in the above formula are for all pixels.

Next, a method of calculating the fractal dimension will be described with reference to FIG.

Here, as a condition, the calculated threshold value is 100.
In the case of a value, 100 or more values are black and the others are white, a black and white binary image is formed, and the total number of black pixels is counted.
When coarse-graining the pixels, in addition to the normal pixels shown in (a), four adjacent pixels shown in (b), nine adjacent pixels shown in (c), and sixteen adjacent pixels shown in (d). Pixel,
... is regarded as one pixel. That is, 1 out of the coarse-grained pixels
If any pixel contains a black pixel, the coarse-grained pixel is regarded as a black pixel. The total number of black pixels in the black-and-white binary image at the time of coarse graining is counted. Next, calculate the fractal dimension.

The fractal dimension D is calculated by the following two equations from the coarse-grained pixel number n and the corresponding black pixel number P (n): log P (n) = a × log (n) + C (C is a constant) ... D = 1-a ... This is because the number of coarse-grained pixels n = 1, 4, 9,
In each case of 16, ..., P (1) of the number of black pixels P (n),
P (4), P (9), P (16), ... Are counted, and the respective values of the coarse-grained pixel number n and the corresponding black pixel number P (n) are substituted into the above equation, and these are calculated. Approximate calculation is performed by the least squares method to obtain a, and then a is substituted into the above equation to calculate the fractal dimension D.

The above-mentioned calculation procedure will be actually described with reference to FIG.

FIG. 5 shows a black and white binary pattern of 12 × 12 144 pixels. (A) The number of black pixels P (n) when n = 1 is 48, and (b) the number of black pixels P when n = 4
(N) is 20 (right shaded area), (c) The number of black pixels P (n) when n = 9 is 11 (left shaded area), (d) n = 16
In this case, the number of black pixels P (n) is 7 (dot area).

Substituting the values at n = 1, 4, 9, and 16 into the equation, each point (log (n), log P
The value of (n) is as follows when n = 1: (log (1), log P (1)) = (0, 1.681)
2) When n = 4: (log (4), log P (4)) = (0.6021,
1.301) When n = 9: (log (9), log P (9)) = (0.9542,
1.0413) When n = 16: (log (16), log P (16)) = (1.204
1, 0.8451). When a is obtained by approximating these points by the least squares method, a = -0.691 is obtained, and when the value of this a is substituted into the equation, the fractal dimension D is D = 1.691.

From the above, by using this basic principle, the surface roughness of the recording medium can be estimated with high accuracy by a simple method. Furthermore, by binarizing the gray scale and calculating the fractal dimension, each image forming parameter value can be easily controlled in accordance with the fractal dimension. Further, since the captured image is binarized and calculated, there is an effect that the amount of data stored in the memory is smaller than that of the method of directly determining the surface roughness, and the time is also efficient.

Embodiments relating to the image forming method and the image forming apparatus according to the present invention based on the above basic principle will be described in detail below.

(First Embodiment) In this embodiment, a case where an image is formed by controlling a toner amount of a laser printer which is an electrophotographic apparatus will be described.

FIG. 6 shows the overall configuration of the laser printer, which includes a paper feeding section 10, an image forming apparatus 20, and a laser scanning section 3.
0 and the fixing device 50.

The paper feeding unit 10 conveys the sheet 1 to the image forming apparatus 20 inside the printer, and the image forming apparatus 20 transfers the toner image onto the conveyed sheet 1. The sheet 1 is further fed, the toner is fixed on the sheet 1 by the fixing device 50, and then discharged by the sheet conveying rollers 41 and 42 to the outside of the printer. That is, the sheet 1 follows the path of the arrow A indicated by the thick line in the figure.

The paper feed section 10 includes a paper tray 11, a paper feed roller 12, a paper separation friction plate 13, a pressure spring 14, paper detection actuators 15 and 15a, paper detection sensors 16 and 1.
6a and a control circuit 17. Further, in the vicinity of the paper feed unit 10, a semiconductor laser 18 and a lens 18 which are light emitting means.
The surface roughness measuring device 100 measures the surface roughness of the paper by irradiating the surface of the paper 1 with a and detecting the shadow image of the reflected light by the CCD 19 which is an image reading means. The paper 1 loaded in the paper feed tray 11 receives a print command, is fed one by one by the action of the paper feed roller 12, the paper separation friction plate 13, and the pressure spring 14, and is fed into the printer. The fed paper 1 depresses the paper detection actuator 15 and causes the paper detection optical sensor 16 to output it as an electric signal to instruct the start of image printing. Control circuit 1 activated by operation of sheet detection actuator 15
Reference numeral 7 sends an image signal to the laser diode light emitting unit 31 of the laser scanning unit 30 to control lighting / non-lighting of the light emitting diode.

The laser scanning section 30 includes the laser diode light emitting unit 31, a scanning mirror 32, a scanning mirror motor 33, and reflection mirrors 35, 36, 37. The scanning mirror 32 is rotated at a high speed and a constant speed by the scanning mirror motor 33. That is, in FIG. 6, the laser beam 34 scans in the direction perpendicular to the paper surface.
The laser light 34 emitted from the laser diode light emitting unit 31 is emitted to the photoconductor 21 to be described later via the reflection mirrors 35, 36 and 37. At this time, the laser light 34
Selectively exposes the photoconductor 21 on the basis of lighting / non-lighting information from the control circuit 17.

The image forming apparatus 20 includes a photoconductor 21, a transfer unit (transfer roller) 22, a charging unit (charging member) 23, and a developing unit (comprising a developing roller 24 and a developing unit 25).
29, and cleaning means (cleaning unit)
It is equipped with 26.

By the laser beam 34, the charging member 2 is previously charged.
An electrostatic latent image is formed by selectively discharging and exposing the surface charge of the photoconductor 21 charged by 3. The toner supplied for development is accumulated in the developing unit 25. The toner to which the electric charge is applied by the appropriate agitation in the developing unit 25 is generated by the action of the developing bias voltage applied to the developing roller 24 and the electric field generated by the photosensitive member surface potential.
An electrostatic latent image can be formed on the photoconductor 21.

The paper 1 conveyed from the paper supply unit 10 is
It is sent by being sandwiched between the photoconductor 21 and the transfer roller 22. Then, due to the action of the electric field given by the transfer voltage applied to the transfer roller 22, the toner on the photoconductor 21 is transferred to the transfer roller 22.
The toner is transferred to the paper 1 by the cleaning unit 26 and the untransferred toner is collected by the cleaning unit 26.

After that, the sheet 1 is conveyed to the fixing device 50. Therefore, an appropriate temperature and pressure are applied by the pressure roller 51 and the fixing roller 52 kept at 155 ° C. As a result, the toner is melted and fixed to the sheet 1 to form a strong image, and the sheet 1 is conveyed by the sheet conveying rollers 41 and 42 and discharged to the outside of the machine.

Below, as the smoothness detecting means, the paper feeding unit 10 is used.
Surface roughness measuring device 10 for measuring the surface roughness of nearby paper
0, and the exposure unit 30 and the charging unit 2 which are image forming units for obtaining good image quality by controlling the amount of toner according to the surface roughness of the sheet based on the measurement result.
3. A control method of the image forming apparatus 20 including the developing unit 29 will be described.

Here, as a method of changing the toner amount, there is a method of changing the surface potential of the photosensitive member or the developing bias. Further, as a method of changing the surface potential of the photoconductor, there are a method of changing the exposure energy of the semiconductor laser in the exposing means and a method of changing the initial charging potential in the charging means. First, a method of changing the toner amount by changing the surface potential of the photoconductor will be described.

In the present embodiment, an example will be described in which the exposure amount is controlled as the control method, so that the toner amount can be controlled in accordance with the surface roughness of the sheet and a good image quality is obtained.

As shown in FIG. 6, the image forming apparatus 20 includes an OPC photosensitive member 21, which is a photoconductor, a transfer unit (transfer roller) 22, a charging unit (charging member) 23, a developing roller 24, and a developing unit. A developing unit 29 composed of 25 and a cleaning unit (cleaning unit) 26 are provided, and the surface charge of the photoconductor 21 previously charged by the charging unit 23 is selectively discharged by a laser beam 34 from an exposing unit (laser scanning unit) 30. To form an electrostatic latent image. Further, a corona discharge device is used as a charger of the charging means (charging member) 23, and is arranged close to the OPC photoconductor 21.

In the structure for measuring and controlling the surface roughness of the paper, as shown in FIG. 7, the light 2a emitted by the semiconductor laser 18 which is the light emitting means 101 becomes almost parallel light by the lens 18a and becomes approximately φ5 mm on the paper 1. After the area irradiation,
The shadow image of the reflected light 2b is detected. The radiated light 2a is shaded by the unevenness of the paper 1 on the reflected light 2b, the concave portion is dark and the convex portion is bright. This shadow image is CCD1
9 and paper 1 as described in the above-mentioned basic principle.
The center line average roughness Ra is calculated, and the image formation control means 104 (FIG. 1) determines and controls the image forming parameter value corresponding to the surface roughness according to the obtained difference in the surface roughness of the sheet 1. In the present embodiment, the image forming parameter value is the light intensity for irradiating the photoconductor 21, and the image forming control means 104 (FIG. 1) is the laser drive control means 104-1 for controlling it. This is because by changing the current of the semiconductor laser 31 drive circuit, as a result, the photoconductor 2
1 can be changed, and the laser drive control means 104-1 controls so that the light intensity emitted by the semiconductor laser 31 (FIG. 6) becomes constant (APC control: Auto Power). Co
control). Therefore, if the surface potential charged on the surface of the photoconductor 21 is set to a constant value and the light intensity applied to the photoconductor 21 is low, the photoconductor 2 is subjected to the subsequent developing process.
The amount of toner adhering to 1 is small, and an electrostatic latent image is formed accordingly. Conversely, when the light intensity is high, the amount of toner that adheres increases, and an electrostatic latent image is formed accordingly.

An image was formed with the above configuration. When the main configuration conditions at that time are listed, the image resolution is 600 dpi,
Peripheral speed of photosensitive drum 16 cm / s, scanning semiconductor laser rated output 5 mW, oscillation wavelength 780 nm (Sharp LT02
8GS) and OPC by non-magnetic 1-component contact development method
An electrostatic latent image was formed on the photoconductor 21 and transferred onto the sheet 1 by the transfer roller 22 which is a transfer means. This paper 1 uses the one described in Table 1 above, and the semiconductor laser 31 (FIG. 6)
The light output of was measured.

FIG. 8 is a diagram showing the relationship between the center line average roughness Ra of the sheet (A4 size) 1 and the toner amount at the time of image formation. Here, each sheet (a, b, c,
The amount of toner adhering to d) is about 0.7-1.0 mg / cm
It was within the range of ² . To get a good image,
It can be seen that a recording medium having a high surface roughness requires a large amount of toner, and a recording medium having a low surface roughness requires a small amount of toner (amount of developer particles).

FIG. 9 is a diagram showing the relationship between the exposure energy of the semiconductor laser 31 (FIG. 6) and the surface potential of the photoconductor 21. It can be seen that when the energy of the semiconductor laser 31 (FIG. 6) is increased, the attenuation of the surface potential of the photoconductor 21 is increased.

FIG. 10 is a diagram showing the relationship between the charging potential on the surface of the photoconductor 21 and the amount of toner adhering to the sheet (A4 size) 1. As can be seen from this, in order to increase the amount of toner attached to the sheet 1, the charging potential may be further attenuated. Therefore, from FIGS. 9 and 10, when the surface potential charged on the surface of the photoconductor 21 is set to a constant value, the amount of toner adhered to the paper 1 can be increased by increasing the exposure energy.

From the above, the semiconductor laser 3 at the time of exposure
The amount of toner can be changed by changing the light intensity of No. 1 (FIG. 6) as an image forming parameter, and the amount of toner can be controlled according to the surface roughness of the paper 1.
As a result, good image quality can be obtained. Therefore, in the present embodiment, the surface roughness of the paper can be estimated by a simple method, and the parameter value of the image formation, here, the light intensity at the exposure means is controlled so as to match the surface roughness of the paper. Thus, an effect that a good image can be formed can be obtained.

In this embodiment, the semiconductor laser is used as the exposure means 30, but another light source such as an LED may be used.

Further, in the present embodiment, the surface roughness measuring device 100 for measuring the surface roughness of the paper 1 is provided near the paper feeding section 10, but the present invention is not limited to this, and the transport path of the paper 1 is not limited to this. It is only necessary that it is arranged upstream of the transfer means (transfer roller) 22 in A.

(Second Embodiment) In this embodiment, the surface roughness of the paper is controlled by controlling the charging means which is the other method of changing the surface potential of the photoconductor as the control method of the image forming means. An example will be described in which the toner amount can be controlled in accordance with the above, and good image quality is obtained. Since the main configuration and operation of the laser printer are the same as those of the above embodiment, only the differences will be described here.

As shown in FIG. 11, in this embodiment, the image forming parameter value is the charging potential, and the image forming control means 104 (FIG. 1) is the charging initial potential control means 104-2 for controlling it. .

As described in the above embodiment, FIG. 10 is a diagram showing the relationship between the charging potential on the surface of the photoconductor 21 and the amount of toner adhering to the sheet (A4 size) 1. As can be seen from this, in order to increase the amount of toner attached to the sheet 1, the charging potential may be further attenuated. That is, in this embodiment, the initial charging potential may be changed depending on the type of paper.

For example, when the uniform charge of −650 V is performed as the initial potential and the exposure energy is set to 10 erg / cm ² , the surface potential of the photoconductor 21 is lowered (attenuated) to about −150 V. Therefore, when the charging potential as the initial potential is changed and the same exposure energy is applied, the amount of attenuation of the surface potential of the photoconductor 21 is different, and when visualization is performed under the same developing condition, the amount of toner adhered to the sheet 1 can be changed. It has become possible.

FIG. 12 shows the exposure energy of 10 erg / c.
is a diagram showing the relationship between residual surface potential after charging the initial surface potential and the exposure of the case gave m ^2. As shown in FIG. 12, when the initial charging surface potential is increased, the residual surface potential is also increased, and accordingly, the amount of toner attached to the sheet 1 can be increased as shown in FIG.

From the above, the residual surface potential changes when the initial charging surface potential is changed with the initial charging potential as the image forming parameter value, and the amount of toner attached to the sheet 1 can be changed accordingly. It is possible to control the amount of toner according to the surface roughness of the sheet 1. As a result, good image quality can be obtained. Therefore, also in the present embodiment, the surface roughness of the paper can be estimated by a simple method, and the parameter value of the image formation, here, the initial charging potential of the charging unit is controlled so as to match the surface roughness of the paper. As a result, an effect that good image formation can be achieved is obtained.

(Third Embodiment) In this embodiment, by controlling the developing means, which is another method of controlling the image forming means, it becomes possible to control the toner amount according to the surface roughness of the paper. An example of obtaining good image quality will be described. Since the main configuration and operation of the laser printer are the same as those of the above embodiment, only the differences will be described here.

As shown in FIG. 13, in this embodiment, the image forming parameter value is used as the developing bias voltage, and the image forming control means 104 (FIG. 1) is the developing bias voltage control means 104-3 for controlling it. is there.

FIG. 14 is an enlarged view of the developing unit (developing tank) 25 and the developing roller 24 constituting the developing means 29. The control of FIG. 13 is performed by controlling the developing means 29 described below. It is something.

In the developing unit 25, 80 to 90% of a thermoplastic resin such as styrene-acryl copolymer, polystyrene, polyethylene, polyester stored in the toner hopper 251 is used, carbon black, furnace black, nigrosine type, xanthene type dye, Coloring materials such as benzine-based, azo-based, copper phthalocyanine-based pigments 5-10
%, Other negatively charged non-magnetic one-component toner having an average particle diameter of 7 μm, which is composed of a composition of a fluidizing agent and a charge control agent
Is stirred and supplied. The supplied toner is agitated by the rotation of the toner carrying roller 253 made of a resin such as ABS or a metal material such as stainless steel, and is supplied to the developing roller 24. The toner supplied by the toner carrying roller 28 rushes into the blade 24a formed of a plate-shaped or block-shaped urethane rubber, nitrile rubber, fluororubber or the like as the developing roller 24 rotates. While passing through the nip portion between the blade 24a and the developing roller 24, an electric charge having a desired polarity is applied by frictional charging.
4 is formed into a thin layer having a uniform thickness on the surface of the developing roller 24.
By applying a voltage to the OPC photosensitive member 21 in the developing area
Developed according to the electrostatic latent image above.

FIG. 15 is a diagram showing the relationship between the developing bias voltage and the amount of toner adhering to the sheet (A4 size) 1 when an image is formed with the above configuration. Here, the developing bias voltage is the difference between the potential applied to the developing roller 24 and the potential on the photoconductor drum 21, and the amount of toner attached to the photoconductor 21 can be increased by increasing the development bias.

From the above, by changing the developing bias voltage with the developing bias voltage as the image forming parameter value, the amount of toner adhering to the sheet 1 can be changed accordingly, and the surface roughness of the sheet 1 can be changed. It is possible to control the amount of toner according to the above. As a result, good image quality can be obtained. Therefore, also in this embodiment, the surface roughness of the sheet can be estimated by a simple method, and the image forming parameter value,
Here, by controlling the developing bias in the developing means, it is possible to obtain an effect that a good image can be formed.

(Fourth Embodiment) The fourth embodiment of the present invention is an example in which any one of the above-mentioned embodiments is applied to obtain the toner amount from the fractal dimension.

[0086]

[Table 2]

Table 2 is a table showing the results of finding the fractal dimension of each sheet by using the method of finding the fractal dimension described in the above-mentioned basic principle, and finding the optimum amount of toner for the black solid printing. Is.

As the measurement condition here, the number of pixels is 28.
For the sake of convenience, the image forming parameter value was set to 8 × 288, and the developing bias voltage was set as the developing bias voltage. By controlling with the same control configuration as in the third embodiment, the optimum toner amount for image forming was obtained.

As shown in FIG. 5, the optimum toner amount at the time of solid black printing is (a) 100% solid black toner adhesion, (b) 75
% Halftone toner adhered, (c) 50% halftone toner adhered, (d) 25% halftone toner adhered, the formed image is magnified 100 times to 200 times with an optical microscope, and the state is determined from the edge and dot shapes. Was visually compared and determined. As a result, it was found that the larger the fractal dimension, the larger the optimum toner amount.

In the embodiment, the developing bias in the developing means is used as an image forming parameter for convenience of description, but the light intensity of the semiconductor laser in the exposing means and the charging initial potential of the charging means with respect to the photosensitive member are used in the image forming. Similar results were obtained when used as a parameter.

From the above, it has been found that an optimum image can be obtained when a toner amount that is approximately proportional to the fractal dimension is given. In other words, as described in the basic principle, by binarizing the gray scale and calculating the fractal dimension, it is possible to control each image forming parameter value corresponding to the fractal dimension, thereby achieving an excellent image formation. can get. In addition, since the captured image is binarized and calculated, a method of directly determining the surface roughness
The amount of data stored in the memory is small, and it is also effective in terms of time.

(Fifth Embodiment) In this embodiment, the operation of the laser printer which is an electrophotographic apparatus after the power is turned on will be described. Since the configuration of the laser printer is the same in any of the above embodiments, only the relevant portion will be described here.

When the power is turned on, the paper 1 is detected by the signal from the paper detection sensor 16a arranged near the paper supply unit 10.
The state of whether or not is checked is confirmed. If the paper 1 is contained, the information detecting means 101 for the paper 1
Roughness measuring device 1 for measuring the surface roughness constituting the
00 starts operation. Further, when the type of the sheet 1 is changed after a lapse of a certain time after the power is turned on, the signal of the sheet detection sensor 16a changes. When the signal is changed, the sheet information detecting means 101 is operated accordingly, new sheet information is obtained, and the printing operation is started. Further, in the case of an image forming apparatus having a plurality of paper feed trays such as a copying machine and a printer, when the user changes the size of the paper 1, the paper information detecting means 101 is automatically operated and the result is obtained. Based on this, the printing operation is performed.

Information about the surface roughness of the paper once measured is stored in the laser printer,
For example, it may be stored in a memory or the like and used. This has the advantage that the time can be shortened because it is not necessary to measure each time.

With the above configuration, the image forming apparatus of this embodiment can obtain a good print image without the user performing a complicated operation.

Further, in the present embodiment, the surface roughness measuring device 100 for measuring the surface roughness of the paper is provided near the paper feeding section 10, but the invention is not limited to this, and the transport path A for the paper 1 is not limited to this. Therefore, it is only necessary to be arranged on the upstream side of the transfer means (transfer roller) 22. That is, a method may be used in which the surface roughness of the paper 1 is measured each time during transportation and the result is reflected in the image formation.

As described above, the respective examples given here are not limited to the above description unless the gist of the present invention is changed.

[0098]

In the image forming method and an image forming equipment according to the present invention exhibits the following effects can be obtained in each claim.

[0099] In the claims 1, 5 of the present invention, <br/> Me where Ru can be estimated with high accuracy the surface roughness of the paper in a simple method and apparatus, so as to conform to the surface roughness of the sheet By controlling the parameter value of each image formation, an effect that good image formation can be performed is obtained. Also, display the surface condition of the paper.
1-dimensional fractal obtained from 2-dimensional image information
The image is supplied so that the amount of toner is approximately proportional to the original information.
Optimal image can be obtained by controlling the formation parameters.
You can

According to the second, third, and fourth aspects of the present invention, the amount of color-developing particles (toner) can be made variable, an image can be formed corresponding to the surface roughness of the paper, and a good image can be obtained. be able to.

[0101]

[0102]

[Brief description of drawings]

FIG. 1 is a main part configuration diagram showing a basic system configuration of a smoothness detector according to the present invention.

FIG. 2 is a processing flow chart showing a basic operation of the smoothness detector according to the present invention.

FIG. 3 is a diagram showing the relationship between voltage and density from a CCD according to the present invention.

FIG. 4 is a process flow chart showing in detail the basic operation of the smoothness detector according to the present invention.

FIG. 5 is an explanatory diagram for calculating a fractal dimension according to the present invention.

FIG. 6 is a cross-sectional configuration diagram of a laser printer equipped with an image forming apparatus according to the present invention.

FIG. 7 is a cross-sectional view of essential parts of an embodiment of the image forming apparatus according to the present invention.

FIG. 8 is a diagram showing the relationship between the center line average roughness and the toner amount during solid black printing according to the present invention.

FIG. 9 is a diagram showing a relationship between exposure energy and a photoreceptor surface potential according to the present invention.

FIG. 10 is a diagram showing the relationship between the surface potential of the photosensitive member and the toner amount during solid black printing according to the present invention.

FIG. 11 is a cross-sectional view of essential parts of another embodiment of the image forming apparatus according to the present invention.

FIG. 12 is a diagram showing the relationship between the initial charging potential and the residual surface potential according to the present invention.

FIG. 13 is a cross-sectional view of an essential part of another embodiment of the image forming apparatus according to the present invention.

FIG. 14 is a detailed cross-sectional view near the developing unit of the image forming apparatus according to the present invention.

FIG. 15 is a diagram showing the relationship between the developing bias and the toner amount during solid black printing according to the present invention.

[Explanation of symbols]

1 Recording medium (paper) 10 Paper feeder 18 Semiconductor laser (for surface roughness detection) 18a lens 19 CCD 20 image forming apparatus 21 photoconductor 22 Transfer means (transfer roller) 23 Charging means (charging member) 24 developing roller 25 Development Unit (Development Tank) 26 Cleaning means (cleaning unit) 29 developing means 30 Laser scanning unit 50 fixing device 100 Paper surface roughness measuring device A paper transport path

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-4-80771 (JP, A) JP-A-8-78492 (JP, A) JP-A-7-190955 (JP, A) JP-A-62-1 235512 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G01B 11/30 G03G 15/00

Claims (5)

(57) [Claims] 1. A charging step for charging the surface of a photoreceptor,
An exposure step of exposing the charged surface of the photoconductor to form an electrostatic latent image, a developing step of developing the electrostatic latent image of the surface of the photoconductor to form a toner image, and the toner image on a recording medium. And an image forming method including a transfer step of transferring the image onto a recording medium, which is calculated from two-dimensional image information representing a surface state of the recording medium.
Based on the fractal dimension information obtained ,
The amount of toner supplied is approximately proportional to the dimensional information.
Image forming method characterized by controlling the image forming parameters for forming an urchin electrostatic latent image or a toner image. 2. The image forming method according to claim 1, wherein the image forming parameter is an irradiation light intensity for forming an electrostatic latent image on the photoconductor. 3. The image forming method according to claim 1, wherein the image forming parameter is an initial charging potential for forming an electrostatic latent image on the photoconductor. 4. The image forming method according to claim 1, wherein the image forming parameter is a developing bias for forming a toner image on the photoconductor. 5. A photoconductor, charging means for charging the surface of the photoconductor, exposure means for exposing the charged surface of the photoconductor to form an electrostatic latent image, and an electrostatic latent image on the surface of the photoconductor. Smoothing detecting means for measuring and detecting the smoothness of the recording medium, and an image forming means comprising a developing means for developing the toner image to form a toner image and a transferring means for transferring the toner image onto the recording medium, and the detecting means. In an image forming apparatus provided with image forming control means for controlling image formation based on a result, the smoothness detecting means includes a light emitting means for irradiating a recording medium with light and a light intensity distribution reflected from the recording medium. the includes a information detection unit for detecting a 2-dimensional image information, the information processing means for converting the fractal dimension information is one-dimensional information performs operations on two-dimensional image information from said information detecting means, wherein Image formation control hand The step is based on the fractal dimension information, which is the one-dimensional information, on the recording medium.
An image forming apparatus, wherein an image forming parameter for forming an electrostatic latent image or a toner image is controlled so as to supply toner in an amount substantially proportional to dimension information .