JP2002199145A - Imaging device and calibration method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow a user to properly handle a recording medium with a patch for calibration to an imaging device recorded thereon without making an error. SOLUTION: When outputting (S101 and S106) and reading (S102 and S107) a test print 1 and a test print 2 with the patch for calibration recorded thereon, a mark recorded on the test print together with the patch is read. Then, it is determined (S103 and S108) whether the read test print is correct or whether it is read at the right position. When reading is not correct, warning to the effect is displayed (S111 and S112).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to an image forming apparatus and a calibration method.

[0002]

2. Description of the Related Art As an image forming apparatus for performing color recording,
For example, a full-color copying machine is known. This color copying machine forms and records images of a plurality of output color components cyan (C), magenta (M), yellow (Y), and black (K) in a sequential manner. The image forming method is, for example, an electrophotographic method using a laser beam, and realizes halftone expression by controlling light emission of the laser beam by a signal that is pulse width modulated according to an image signal.

In such an image forming apparatus, the density of an image to be formed and its gradation are affected by changes in the environment in which the apparatus is placed or changes over time of device elements such as a photoconductor and a developer. And may cause deterioration or instability of image quality. On the other hand, a predetermined patch pattern is formed on, for example, a photosensitive drum or a recording medium, and based on the density read from the patch pattern,
It is known to perform so-called calibration for correcting density or gradation in image formation by the apparatus.

[0004]

However, a recording medium on which a patch is recorded in the above-mentioned calibration is used.
(Hereinafter, also referred to as "test print"), it may not be possible to perform accurate calibration.

For example, when a test print to be read is different, that is, even if a test print recorded by another apparatus is erroneously read and calibration is performed based on the result, the calibration is performed only for the image to be originally calibrated. This is based on a test print in which the recording characteristics of the forming apparatus are not reflected, so that accurate calibration cannot be performed. Such a situation is likely to occur by a user who performs calibration in an environment where a plurality of image forming apparatuses such as printers and copiers are used by being connected via a network.

As another example of erroneous test printing, a relatively long time has passed since the recording of the test print, and the recording characteristics of the image forming apparatus have already changed, and the test print has been replaced with the current print. This is the case where the recording characteristics are not reflected.

Further, when reading a test print, the user usually needs to perform an operation of placing the test print on a document table or a scanner. At this time, the test print may not be placed at a position suitable for reading.

[0008] The present invention has been made to solve the above-mentioned problems, and an object thereof is to provide a user with:
An object of the present invention is to provide an image forming apparatus and a calibration method that can appropriately handle test prints during calibration and provide an easy-to-use image forming apparatus.

[0009]

According to the present invention, there is provided:
An image forming apparatus for forming an image on a recording medium, wherein in the image forming apparatus for calibrating the recording characteristics, test print means for outputting a test print in which a predetermined image for the calibration is recorded on a recording medium, Determining means for determining, based on a read result of the test print output by the test print means, a type of the test print and whether the test print has been read at a regular position.

According to another aspect, there is provided an image forming apparatus for forming an image on a recording medium, the test printing comprising a predetermined image for the calibration recorded on the recording medium in the image forming apparatus for calibrating the recording characteristics. And a determination means for determining, based on the read result of the test print output by the test print means, the time since the test print was output.

According to still another aspect, in an image forming apparatus for forming an image on a recording medium, the image forming apparatus for calibrating the recording characteristics includes a test in which a predetermined image for the calibration is recorded on the recording medium. Test print means for outputting a print; and judgment means for judging, based on a read result of the test print outputted by the test print means, a model of the image forming apparatus which has output the test print. .

Preferably, the determination means determines that the test print is different, that the test print was not read at a proper position, and that a time after outputting the test print has exceeded a predetermined time. If it is determined that the image forming apparatus is different or the model of the image forming apparatus is different, a notifying means for notifying the user to that effect is further provided.

In a calibration method for calibrating recording characteristics of an image forming apparatus for forming an image on a recording medium, a test print in which a predetermined image for the calibration is recorded on the recording medium by the image forming apparatus. And a step of judging the type of the test print and whether or not the test print has been read at a proper position based on the read result of the output test print.

According to another aspect, in a calibration method for calibrating recording characteristics of an image forming apparatus for forming an image on a recording medium, a predetermined image for the calibration is recorded on the recording medium by the image forming apparatus. Outputting the test print, and judging the time from when the test print was output based on the read result of the output test print.

According to still another aspect, in a calibration method for calibrating recording characteristics of an image forming apparatus for forming an image on a recording medium, a test print in which a predetermined image for the calibration is recorded on a recording medium is provided. Output, based on the read result of the output test print,
Determining a model of the image forming apparatus that has output the test print.

[0016] Preferably, the judging step is that the test print is different, that the test print was not read at a regular position, and that a time after outputting the test print has passed a predetermined time or more. And determining that the model of the image forming apparatus is different, and notifying the user of the determination.

According to the above arrangement, when performing calibration for calibrating the recording characteristics of an image forming apparatus for forming an image on a recording medium, the result of reading a test print on which a predetermined image for calibration is recorded is obtained. Based on the type of the test print and whether the test print was read at a regular position, the time since the test print was output or the model of the image forming apparatus that output the test print is determined. Preferably, in these determinations, the test print is different, the test print was not read at a proper position, and the time since the test print was output has passed for a predetermined time or more. That, or when it is determined that the model of the image forming apparatus is different,
Since the user is notified of the fact, it is possible to read the test print satisfactorily in the calibration without paying much attention to the handling of the test print.

[0018]

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

Although the present embodiment relates to a case where the present invention is applied to a full-color copying machine, it will be apparent from the following description that the application of the present invention is not limited to this embodiment.

[Overview of Image Forming Apparatus] FIG. 1 is a schematic sectional view showing a copying machine as an image forming apparatus.

In the mechanism for copying a document in a copying machine shown in FIG. 1, reference numeral 201 denotes a platen glass on which a document 202 to be read is placed. When reading the original 202, an illumination 203
And the reflected light is reflected by mirrors 204 and 20
After passing through steps 5 and 206, the CCD 208 is operated by the optical system 207.
It is incident on the top and forms an image. At this time, the first mirror unit 210 including the mirror 204 and the illumination 203 is mechanically driven at a predetermined speed V by the driving force of the motor 209, and the second mirror unit 2 including the mirrors 205 and 206.
11 is driven at a speed of 1 / 2V. Thus, the entire surface of the original 202 is scanned and read.

This reading mechanism is also used for reading a test print during calibration described later.

Next, the image processing circuit 212 processes the image information optically read as described above as an electric signal, and temporarily stores the image information in the image memory 108 (see FIG. 2). This signal, as described below in FIG.
Output as a print signal. Image processing circuit section 212
The print signal output from is sent to a laser driver (not shown), and the laser driver, based on the print signal, corresponds to the four color toners as a recording material for image formation.
Similarly, four semiconductor lasers (not shown) are driven.

That is, these four semiconductor lasers corresponding to each color include cyan (C) and magenta.
Print signals corresponding to (M), yellow (Y), and black (K) are sent, and these semiconductor lasers emit laser light at predetermined timings in accordance with the print signals. The emitted laser light is incident on the polygon mirror 213, and the laser light for yellow image formation is incident on the photosensitive drum 217 via the mirrors 214, 215, and 216, and is scanned by the laser light. I do. Similarly, laser light for magenta image formation is reflected by mirrors 218, 219, and 220.
Scans the photosensitive drum 221 via the mirror, the laser beam for cyan scans the photosensitive drum 225 via the mirrors 222, 223 and 224, and the laser beam for black
The photosensitive drum 22 via the mirrors 226, 227, 228
Scan 9

The latent images of respective colors formed on the respective photosensitive drums in this manner are supplied to the developing units 230 for supplying yellow toner, the developing units 231 for supplying magenta toner, and cyan on the respective photosensitive drums. The toner is developed as a toner image of each color by a developing device 232 that supplies the toner of the same color and a developing device 233 that supplies the black toner.

Each color (Y, M,
The C, K) toner images are sequentially transferred to the conveyed paper, whereby a full-color output image can be obtained.

The sheets are stored in sheet cassettes 234 and 23.
5 or the manual feed tray 236. That is, the paper fed from the paper cassette or the manual feed tray is fed by the registration roller 237 at the timing of feeding, and fed onto the transfer belt 238 in synchronization with the timing of development on the photosensitive drum. The transfer belt 238 attracts and transports the sheet by the electrostatic force. Then, as described above, the toner images of each color previously formed on the photosensitive drums 217, 221, 225, and 229 are sequentially transferred to the paper.

The sheet onto which the toner of each color has been transferred is separated from the transfer belt 238 and then conveyed by a conveyance belt 239. During this time, the toner is fixed by the fixing device 240, and then the sheet is discharged to the sheet discharge tray 241.

In the case of double-sided recording, sheets fed from one of the paper cassettes 234 and 235 and the manual feed tray 236 are similar to those in the case of single-sided recording described above.
A toner image is formed and fixed on the first surface of the sheet. Thereafter, unlike in the case of single-sided recording, the sheet is conveyed to the double-side reversing unit 245 by controlling the conveyance of the sheet so that the sheet passes through the discharge vertical path 246 by the discharge deflection plate. Then, after the lapse of the specified time, the rollers at the double-sided reversing unit are rotated in the reverse direction, and the sheet is reversed, conveyed to the double-sided path pre-conveying unit 247, and conveyed to the double-sided path 244. At this time, the upper side of the sheet on the double-sided path 244 is the first surface on which the image has been formed. When the sheet is conveyed to the two-sided path, the sheet is aligned, and then the sheet is immediately re-supplied by the above-described sheet feeding path from the sheet cassette or the like. After passing through the fixing device 240,
The paper is discharged to the paper discharge tray 241. When two-sided printing is continuously performed on a plurality of sheets, re-feeding from the above-described two-sided pass and feeding from the sheet tray are performed alternately.

[0030] In addition, four of the photosensitive drum 217,221,
225 and 229 are arranged at regular intervals at a distance d, and the transfer belt 238 allows the paper to move at a constant speed v.
As described above, the driving of the four semiconductor lasers and the formation of the toner image on the photosensitive drum are performed in synchronization with this speed.

[Flow of Image Signal] FIG. 2 is a block diagram showing the configuration of an image processing circuit in the above-described image forming apparatus and the flow of an image signal in the circuit.

[0032]

(Equation 1)

In FIG. 2, as described above with reference to FIG.
By irradiating the original image, the image read by the CCD sensor 208 is output as image data for each of three color components of red (R), green (G), and blue (B). It is converted (not shown) and output as digital signals R0, G0, B0, respectively.
The input masking circuit 112 performs a color correction on these signals to an input device (such as a reading optical system) by an operation according to the following equation. As a result, the input signal R
0, G0, B0 are converted to standard signals R, G, B.

Here, cij (i = 1, 2, 3, j =
1, 2, and 3) are device-specific constants determined in consideration of various characteristics of the input device, such as sensitivity characteristics of the CCD sensor / spectral characteristics of the illumination lamp.

Next, the color-corrected signals R, G, and B are converted into Y,
It is converted into M and C signals.

This conversion unit is constituted by a look-up table stored in a RAM or a ROM, and conversion is performed by the following operation.

[0037]

C1 = −α × log ₁₀ (R / 255) M1 = −α × log ₁₀ (G / 255) (2) Y1 = −α × log ₁₀ (B / 255) (α is a constant)

[0038]

(Equation 3)

Next, output masking / @ CR circuit section 10
In step S6, a masking process and an undercolor removal process related to the output device are performed, and based on the signals M1, C1, and Y1 from the luminance / density conversion unit 104, the color Y of the toner in the above-described image forming apparatus according to the present embodiment. , M, C, K
To generate a signal. In this processing, an operation is performed according to the following equation.

Here, aij (i = 1, 2, 3, 4 j
= 1, 2, 3, 4) are device-specific constants that take into account various characteristics of the output device, such as the tint realized on the paper by the toner, and K1 is

[0041]

K1 = min (C1, M1, Y1) (4)

The signals C1, M1, Y1, and Y2 based on the R, G, and B signals output from the CCD sensor 208 by the respective conversion processes based on the above equations (2), (3), and (4).
K1 is a signal C, M, based on the spectral distribution characteristics of the toner.
It is converted to Y and K.

On the other hand, the character / line drawing detection circuit 105 is based on the signals R, G, and B from the input masking circuit 112,
It is determined whether or not each pixel of the read image forms a part of a character or a line drawing, and a determination signal TEX is provided.
Generate T. Also, the compression / expansion circuit 107
The determination signal TEXT output from the line drawing detection circuit 105 and the image signal Y1 output from the luminance / density conversion circuit 104
M1 and C1 are compressed and stored in the memory 108 with the amount of information reduced, and the determination signal TEXT and the image signal read from the memory 108 are expanded. A description of a compression / decompression circuit for images other than characters and line drawings is omitted.

The gamma correction circuit 312 is constituted by a look-up table (LUT), and performs gamma correction on the image signal according to the output density characteristics of the printer.

[Timing of Image Forming Operation] The image forming operation of the image forming apparatus of the present embodiment described above, particularly the transfer timing of image data, will be described.

FIG. 3 is a timing chart showing the timing of writing to and reading from the memory 108 in this image data transfer.

In the copying machine operation, as shown in FIG.
The image data read in D208 passes through the input masking circuit 112 and the luminance / density conversion unit 104, is compressed by the compression / expansion circuit, and is then written into the memory 108 (timing 401). Character / line drawing determination circuit 1
The character / line drawing determination signal TEXT and the image signal output from 05 are also compressed in the compression / expansion circuit 105 and then written into the memory 108 (timing 401).

After a lapse of a predetermined time from the writing, the image signal is read out from the memory 108. The read image signal is supplied to a compression / expansion circuit 107.
And is transferred to a laser driver through a PWM circuit described later with reference to FIG. 4 according to the image forming timing of the copying machine.

That is, as shown in FIG.
In the image signal written in 8, first, after the writing, a yellow image signal is read out after a predetermined time (timing 402). Next, thereafter, a magenta image signal is read (timing 403). Similarly, cyan and black image signals are sequentially read out at intervals of d / v (timings 404 and 405).

Here, as described above, d is the interval between four drums arranged at equal intervals, and v is the speed of the sheet conveyed by the transfer belt.

[PWM Circuit] FIG. 4 is a block diagram showing a configuration of the PWM circuit according to the present embodiment. The configuration shown in FIG. 4 corresponds to an image signal of one color, and the image forming apparatus of the present embodiment includes the configuration shown in FIG. 4 for each of Y, M, C, and K colors.

In FIG. 4, a D / A converter 601 converts an input digital image signal into an analog signal, and sends the analog signal to a comparator 605. Triangular wave generator 6
Reference numeral 02 is used when recording an image in which gradation is emphasized, and generates a triangular wave at a cycle of one pixel of an image signal transfer. Another triangular wave generator 603 is a triangular wave generator for recording an image where importance is placed on resolution, and generates a triangular wave in two pixel cycles of image signal transfer. Then, the selector 604 selects one of the two triangular waves according to the character / line drawing determination signal positive XEXT, and sends the selected triangular wave to the comparator 605.

With the above configuration, when the determination signal TEXT is "1", that is, in the case of an image signal forming a character or a line drawing, the image output from the triangular wave generator 603 is emphasized by the comparator 605. And the analog signal from the D / A converter 601 are compared. On the other hand, when the determination signal TEXT is “0” and the image signal is determined to be an image signal other than a character or a line drawing, a triangular wave for an image that emphasizes the gradation output from the triangular wave generator 602 and an analog signal of the image are output. Are compared by the comparator 605. An output as a comparison result of the comparator 605 is input as a PWM signal to a laser driver 606 that drives a semiconductor laser driver element.

FIG. 5 is a diagram showing a state of pulse width modulation by the comparator 605. In the drawing, the upper pulse width modulation shows the state of pulse width modulation in an image where importance is placed on gradation, and the lower row shows the state of pulse width modulation in an image where importance is placed on resolution.

In the upper stage pulse width modulation, the D / A converter 6
01 is compared with a triangular wave 802 having a period of two pixels to obtain a PWM signal 803. On the other hand, in the lower part of the pulse width modulation, the output 804 of the D / A converter 601 is compared with a triangular wave 805 of a pixel period to obtain a PWM signal 806.

In actual image processing, an image to be processed includes an image that prioritizes gradation and a line image that prioritizes resolution. Are switched according to the determination signal TEXT and are output depending on whether a part of the image has priority. As a result, a preferable image is formed in accordance with the image area characteristics of the image to be formed.

[First Embodiment] A first embodiment of calibration (also referred to as "automatic tone correction" in the following embodiments) for calibrating the recording characteristics of an image forming apparatus based on the above configuration. Will be described. In the present embodiment, two types of automatic gradation corrections, that is, a first automatic gradation correction and a second automatic gradation correction, are performed in order to obtain an appropriate image density and gradation when forming a full-color image. These automatic gradation corrections are performed by the user selecting one of the first and second automatic gradation corrections by, for example, a predetermined key operation on an operation panel of the image forming apparatus. be able to.

(First Automatic Gradation Correction) The first automatic gradation correction includes a first control and a second control. In the first control, the gamma correction 312 (see FIG. 2) in the image processing is performed. A process for changing the correction characteristics, specifically, the contents of the LUT is performed. In the second control, a process for correcting the toner supply amount to the developing units 230 to 233 (see FIG. 1) is performed. This makes it possible to perform calibration for stably and appropriately adjusting the density or gradation of the recorded image.

First Control FIG. 6 is a flowchart showing a processing procedure of the first control. 7 (a), 7 (b), 8 (a), 8 (b), 9
FIGS. 3A and 3B are diagrams illustrating display examples according to first control on an operation panel of the image forming apparatus according to the embodiment. FIGS.

"Automatic gradation correction" (not shown) on the operation panel
When the key is pressed, the first control starts. First,
In step S101 shown in FIG. 6, the screen shown in FIG. 7A is displayed on the operation panel. When the user presses the "test print 1" key, test print 1 is output. At this time, if there is no recording paper required for recording the test print 1, a warning is displayed. When printing the test print 1, a standard contrast potential (described later) according to the environmental conditions of the image forming apparatus is used as an initial value.

As shown in FIG. 10, the test pattern 1 has a band pattern patch 1001 consisting of four intermediate gradation densities of Y, M, C, and K, and the maximum densities of Y, M, C, and K, respectively. (Density signal level 255) patch 1002,
1003, 1004 and 1005.

Further, in this embodiment, the test print 1 has "1" indicating that it is the test print 1.
And a mark "up" indicating the direction of the test print are recorded together with the recording of each patch. Thereby, the user can confirm that the test print is the test print 1 to be recorded first in the first control by seeing the mark “1”, and also, when reading, as described later. Whether or not the test is correct can be automatically determined based on the mark. Similarly, the mark “up” can confirm the correct orientation of the test print when the test print 1 is placed on the original glass platen 201 (see FIG. 1) for the test print reading. In this case, the determination can be made automatically. As a result, it becomes possible for the user to appropriately handle the test print for calibration without erroneous operation. Next, in step S102, the screen shown in FIG. 7B is displayed on the operation panel. Is done. And the user
The output test print 1 is placed on the platen glass 20.
1 and press the "read" key, the test print 1 is read.

In step S103, the following determination is made with respect to the test print in accordance with the mark 1006 read at the same time as the above reading. That is, whether or not this mark is recorded, whether or not a different mark is recorded even if it is recorded, and further,
In particular, it is determined whether or not the test print is placed in the correct direction depending on whether or not the mark “up” is detected. Then, a document other than Test Print 1 is placed on the platen, or how to place Test Print 1 on the platen.
If it is determined that the (orientation, etc.) is not correct, step S11
In step 1, as shown in FIG. 9A, a warning message is displayed on the operation panel. On the other hand, when the user puts the correct test print or the orientation correctly on the original glass table and presses the reading key shown in the figure, the reading in step S102 is performed again.

The above-described determination of the placement of the test prints is made based on the read data. For example, when the data of the mark 1006 cannot be read at the original position due to the positional relationship with the patch to be read, or when the read data is different, it is determined that the test print is not placed at the correct position or orientation. Also,
It will be determined that the test print is different.

In step S102, R, G, and R as read data of each patch of the test print 1 are read.
The B data is an LU of the brightness / density conversion unit 104 shown in FIG.
It is converted to an optical density by T. This brightness / density converter 1
The LUT 04 uses the inputs of R, G, and B as addresses, and C1, M obtained by the above equation (2) based on these values.
1, Y1 are output, and an interpolation operation is used as necessary.

In step S103, when it is determined that the test print 1 has been correctly placed on the original glass platen and the reading has been correctly performed, in step S104, the contrast potential for the photosensitive drum of each color is obtained based on the read data. The correction coefficient is optimized.

The contrast potential Vb is generally obtained by the following equation.

[0068]

Vb = (Va + ka) × 1, 7 / Da (5) where Va is the surface potential of the photosensitive drum, and Da is
It is a density of a toner image to be realized by it. Then, ka is a correction value. In step S104, the value of ka is optimized.

That is, in steps S104 and S105, correction is performed based on the density information obtained by the reading in step S102 so that the maximum density when a toner image is formed on the photosensitive drum becomes a predetermined value. In step S104, first, a process of optimizing the value of ka so as to obtain the contrast potential Vb that enables a desired maximum density is performed by the above equation (5).

FIG. 11 shows the relationship between the relative value of the surface potential of the photosensitive drum (hereinafter, simply referred to as “surface potential”) when each patch of the test print is formed, and the density information of the toner image obtained thereby. FIG.

The horizontal axis indicates the contrast potential when the test print 1 was formed, that is, the surface potential difference when a latent image was formed by the laser on the photosensitive drum that was primarily charged by the developing bias potential determined by the test potential. The vertical axis indicates the toner density realized by the surface potential. Va in the equation (5) is the surface potential of the photosensitive drum when scanned by the laser beam output from the semiconductor laser element driven at the maximum light emission level in the relationship shown in FIG. Is the maximum density of the toner image realized by the above.

As shown in FIG. 11, in a region near the maximum density, the density value relative to the surface potential of the photosensitive drum is usually
In many cases, a linear relationship as shown by a solid line L in FIG. 11 is obtained. However, in the two-component developing system, when the toner density in the developing device changes and decreases, as shown by a broken line N in FIG. In a region near the density, the density value with respect to the surface potential of the photosensitive drum may become non-linear. Therefore, in order to realize the final target value 1.6 of the maximum density, 1.7 is set as the target value of the maximum density in consideration of a margin of 0.1. Then, as shown in equation (5), this target value 1.7
The contrast potential Vb is determined according to the ratio of the contrast potential Vb to the actually realized density Da, and ka is used as a correction value at that time. The value of ka depends on the type of developing method and the like, and is determined according to these developing methods and the like.

Next, in step S105, based on the contrast potential Vb based on the value of ka obtained above,
The grid potential and the developing bias potential are obtained.

FIG. 12 is a diagram showing an example of the relationship between the grid potential and the surface potential of the photosensitive drum.

The grid potential Vg is set to Vg1 = −300 V, the surface potential Vd when the photosensitive drum is scanned with a laser beam while the light emission level of the semiconductor laser element is minimized.
1, and the surface potential V when the photosensitive drum is scanned with the laser beam while the light emission level of the semiconductor laser element is maximized.
11 is measured using a surface electrometer 708 shown in FIG. FIG. 13 shows a developing device and a photosensitive drum for yellow (see FIG. 1).
7 at a predetermined position.

Similarly, the grid potential Vg is set to Vg2 = −7.
Vd2 and Vl2 when set to 00V are measured. The resulting grid potentials are -300 V and -700
By interpolating and extrapolating the surface potential data at each V, the relationship between the grid potential Vg and the surface potential of the photosensitive drum indicated by a straight line in FIG. The control for obtaining the potential data is referred to as “potential measurement control”.

Then, a predetermined potential difference Vback (for example, 150 V) is provided and the developing bias Vdc is set so that so-called fogging toner which adheres to the image from the generated Vd does not occur. And the contrast potential Vb is
It can be obtained as a difference voltage between the developing bias Vdc and the surface potential Vl.
The maximum concentration can be increased. Further, the grid potential Vg and the developing bias potential Vdc for obtaining the obtained contrast potential Vb can be obtained from the relationship shown in FIG.

As described above, in the present embodiment, in step S104, the contrast potential Vb is obtained so as to obtain the target value 1.7 of the maximum density.
Then, the grid potential Vg and the developing bias potential Vdc are set so that the contrast potential Vb is obtained.

After performing the correction processing of the grid potential and the like for setting the maximum density described above, the next step S10
From 6 onward, processing is performed to correct the conversion characteristics of the gamma correction circuit 312 (see FIG. 2).

Here, the role of the gamma correction and the process of correcting the gradation by using the gamma correction will be described. FIG.
5 is a characteristic conversion chart showing an example of a density reproduction characteristic.

[0081] The first region I shown in FIG. 14, the original image of the document reading system of the image forming apparatus of the present embodiment shows an image reading characteristic for converting the density signal, the second region II is a gamma correction to the density signals Shows the conversion characteristics of the γ correction circuit 312 that performs
A third area III indicates an output density characteristic (gamma characteristic) in recording of the image forming apparatus, which indicates a relation between the laser output signal and the image density, and a fourth area IV indicates a relation between the document density and the output image density. Is shown. That is, the characteristics of the fourth region IV represent the overall gradation characteristics in the image forming apparatus.

As shown in FIG. 14, in the present embodiment, since an 8-bit digital signal for each color is used as an image signal, the gradation of each color is 256. Further, the gamma characteristic of the present image forming apparatus in the third region III is indicated by a solid line J by the above-described maximum density control for setting the target value of the maximum density higher. If the control for increasing the target value of the maximum density is not performed, the gamma characteristic of the present apparatus is represented by a solid line H
As indicated by, the target density may not reach 1.6. That is, in the case of an image forming apparatus exhibiting the characteristic of the solid line H, the maximum density cannot be largely corrected no matter how the gamma correction circuit is set, so that the density between the density DH and the density 1.6 is not obtained. Cannot be reproduced.

In the image forming apparatus of the present embodiment, in order to make the overall characteristics of the fourth region IV linear, the second region II is changed in accordance with the gamma characteristic of the device itself shown in the third region III. The content of the gamma conversion characteristic of the shown gamma correction circuit 312 is determined. That is, by performing the correction by the gamma correction circuit 312 thus determined, the fourth area
The relationship indicated by IV can be made linear, and appropriate gradation recording can be performed. Gamma correction circuit 312
Can be easily obtained by simply reversing the input / output relationship of the gamma characteristic shown in the third region III.

The recording of test print 2 in step S106 is performed according to the display on the operation panel shown in FIG.
It is activated when the user clicks the button of test print 2. When the test print 2 is output, the gamma correction function of the gamma correction circuit 312 is stopped. That is, in the image processing shown in FIG. 2, the test print 2 is recorded based on the test print data generated without performing the gamma correction by the gamma correction circuit 312.

In the present embodiment, the test print 2 includes
As in the case of the test print 1, as shown in FIG. 15, a mark 1109 indicating that the recorded patch is that of the test print 2 and the direction of the test print is recorded together with the patches of each color.

As shown in the figure, the patches of each color include Y patch groups 1101 and 1105, M patch groups 1102 and 1106, C patch groups 1103 and 1107, and K patch groups 1104 and 1108. Are gradation patches for 64 tones in 4 rows and 16 columns. The 64 patches in each patch group mainly include the tone values in the low density region among the 256 tone levels, so that the tone characteristics in the highlight portion can be satisfactorily adjusted. . For each color, the patch groups 1101, 1102, 1103, and 1104 have a resolution of 200 LPI (line / inch).
, While the patch groups 1105 and 110
6, 1107 and 1108 are constituted by patches having a resolution of 400 LPI. Note that a patch group having the same gradation may be output at two resolutions. However, if the gradation characteristics are significantly different due to the difference in resolution, a gradation value according to the resolution may be set.

When the recording and output of the test print 2 described above is completed, a screen shown in FIG. 8B is displayed on the operation panel, and the user prints the test print 2 output in response to the screen on the platen glass 201. When the user presses the "read" key on the same screen, the process proceeds to step S107, and the test print 2 is read.

With this reading, step S108
Then, it is determined whether a document other than the test print 2 is placed on the platen and whether the test print 2 is properly placed on the platen. Different manuscripts are placed,
If it is determined that the orientation is not correct, step S1
At 12, a warning message shown in FIG. 9B is displayed on the display screen of the operation panel. On the other hand, if the user correctly sets the test print 2 on the platen and presses the reading key shown in FIG.
At step 7, a test print is read.

Whether the placement of the test print 2 on the platen or the like is correct can be determined based on the mark 1109 at the time of reading, as in the case of the test print 1 described above.

Next, in step S109, the density information output from the luminance / density conversion unit 104 by reading the test print 2 is stored in the memory together with the laser output level and the position information of the corresponding patch. At this stage, the gamma characteristic shown in the third region III of FIG. 14 can be obtained, and then, in step S110,
The gamma conversion characteristic of the gamma correction circuit 312 is set based on the data obtained by replacing the input / output relationship of the obtained gamma characteristic. When the gamma conversion characteristics are obtained as described above, 0
Among the tone values of .about.255, tone values other than the tone value of the patch recorded as test print 2 are obtained by interpolation so that these values correspond to the laser output level.

Second Control In the present embodiment, as the first automatic gradation correction, the following second control is performed in addition to the above-described first control.

[0092] In the photosensitive drum, when continuously performing development with a developer for the latent image formed, the concentration of the toner in the developing device may result in lowering of developability and deterioration. In addition, a change in the developability also occurs due to a change in the surrounding environment, repetition of the development process, and the like, and as a result, the density and the tone reproducibility of the image may change.

In the present embodiment, as a second control, a test pattern is formed on a photosensitive drum in order to suppress changes in image density and tone reproducibility and obtain stable density and tone reproducibility. The density is detected by an image density sensor 709 (see FIG. 13) installed at a position facing the photosensitive drum, and image density detection control for correcting image density or gradation reproducibility is performed. Furthermore, regarding image formation of chromatic colors,
A developer concentration detection control for detecting and correcting the toner concentration of the developer in the developing device by a toner concentration sensor installed in each developing device is also performed. The image density sensor 709
The toner concentration sensor can be configured by, for example, a light emitting unit of an LED and a light receiving unit of a photodiode that receives light output from the light emitting unit.

In the present embodiment, in the chromatic developing process, that is, in the image formation of each of the Y, M, and C colors, the signal output by the image density detection control is used for the developer density detection control. Hereinafter, the developer concentration detection control will be described with reference to the image formation of Y as an example.

The developing device 230 includes a toner density sensor
(Not shown) is provided. This toner concentration sensor
It uses the property that the toner in the two-component developer reflects infrared light, and conversely, the carrier absorbs infrared light. In other words, the developer in the developing device 230 is irradiated with infrared light by the LED, and the amount of infrared light reflected by the developer is detected by the photodiode to calculate the toner concentration of the developer. Then, the image density is corrected by replenishing the developer according to the calculated toner density. Specifically, it is as follows.

First, the amount of reflected light of the developer in a state where the developer is not used immediately after the toner is supplied to the developing device 230 is measured by a photodiode, and the measured output of the photodiode is defined as SIG (init-Y). I do. This SIG (in
It-Y) is stored in the memory as a control target value of the toner concentration of the developer.

Next, when the image forming process is started and the use of the developer is started, the output SIG (cal−cal−) of the photodiode relating to the developer at that time is formed every time an image is formed.
Y) is measured, and the difference △ SIG from the SIG (init-Y) stored in the memory is calculated by the following equation (6).

ΔSIG (Y) = SIG (init−Y) −SIG (cal−Y) (6) ΔSIG (Y) obtained by the equation (6) is equal to 1 of the toner density measured in advance. The deviation ΔD from the initial value of the toner density at that time is calculated by the following equation (7) based on the output sensitivity value RATE with respect to the fluctuation of the weight%.

△ D = △ SIG / RATE (7) The amount of toner supplied into the developing device 230 is determined by the calculated value of the shift amount △ D. In other words, when the shift amount ΔD is negative, the toner corresponding to the shift amount ΔD is supplied,
When the shift amount ΔD is positive, the supply of toner is stopped. For example, when ΔD is −1% by weight, toner equivalent to 1% by weight is supplied, and when ΔD is + 1% by weight, toner is not supplied. In this way, control is performed to maintain the initial toner concentration.

Next, the image density detection control will be described. The image density detection control is executed at a predetermined timing, and forms a patch image on the photosensitive drum 217 as a reference image for density detection. That is, a patch image signal of a signal level corresponding to a predetermined density generated by the pattern generator is supplied to the PWM circuit. As a result, an electrostatic latent image of a patch corresponding to a predetermined density is formed on the photosensitive drum 217, and the electrostatic latent image of the patch is developed by the developing device 230. Note that the signal level is set so that the density of the patch to be developed is a value at which the development characteristics are most easily controlled. This makes it possible to control not only the image density but also the gradation reproducibility to desired characteristics.

Next, the density of the patch toner image is measured by the image density sensor 709. The measured patch density corresponds to the toner density of the developer in the developing device 230.

More specifically, the signal S (si) output from the photodiode of the image density sensor 709 is
gY) is supplied to one input terminal of a differentiator (not shown). A reference signal S (int-Y) corresponding to a specified density (initial density) of the patch is applied to the other input terminal of the differentiator.
Is entered. Accordingly, a signal S (cal-Y) indicating the difference between the density of the patch toner image and the initial temperature, that is, the difference in the density of the patch toner image, is output from the differentiator. And this signal S
(cal-Y) is supplied to the CPU of the image processing circuit unit 212.

This signal S (ca1-Y) is used for correcting the toner supply control to the developing device 230 by the developer concentration detection control described above. In general, as the toner concentration of the developer increases, the image density increases, and conversely, the image temperature at which the toner concentration of the developer decreases decreases. In addition, a change in development efficiency occurs due to environmental fluctuations or changes over time in device elements. Therefore, stable image density is not guaranteed only by the developer density detection control described above. Therefore, in the present embodiment, the target value SIG (init-Y) of the developer density detection control is adjusted based on the signal S (ca1-Y) indicating the density difference obtained by the image density detection control.

More specifically, for example, assuming that the initial toner concentration of the developer is 6% by weight, the toner is supplied so that the toner concentration becomes 6% by weight based on the output of the toner concentration sensor. state, performs image density detection control, low density of the patch is compared to the initial concentration, if the toner to return to the initial concentration is determined to be necessary 5g, current toner concentration is from about 1 wt% low It is considered to be in a state.
Accordingly, the target value of the developer concentration detection control is changed from 6% by weight to a new target value SIG (tgt-Y) of 7% by weight, and thereafter, the developer concentration detection control is performed based on the new target value. I do. This makes it possible to maintain the image density at a desired value. In the developing device of this embodiment, 5 g of the toner corresponds to about 1% by weight. However, if the developing device is different, this value is of course different.

(Second Automatic Tone Correction) According to the second control in the first automatic tone correction described above, the toner density of the developer is controlled, and the density of the patch formed on the photosensitive drum is controlled. By correcting the control target value of the toner density, it is possible to suppress the fluctuation of the developing characteristic and to stably maintain the image density and the tone reproducibility.

However, the image density and the tone reproducibility are not determined only by the development characteristics corrected by the second control. For example, the image density and the gradation reproducibility fluctuate due to various factors such as a change in the light attenuation characteristic of the photosensitive drum, a change in the intensity of the laser beam, and a fluctuation in the mechanical accuracy of the apparatus. It may be relatively difficult to absorb changes in image density and gradation reproducibility due to these factors by only the first control in the first automatic gradation correction described above. In other words, when the variation due to the above factors is corrected by the first control, the condition of the second control is changed, so that not only the desired control performance cannot be obtained, but also the amount corrected by the first control. In some cases, the second control returns to the original state, that is, returns to a defective state before correction.

Therefore, in the present embodiment, in order to more effectively apply the first control and the second control, the second control is performed based on the result of the first control. Automatic gradation correction can also be executed. Hereinafter, the control of Y will be specifically described by way of example.

The patches in the image density detection control are formed at a predetermined optimum density in order to guarantee gradation reproducibility. That is, the patch image signal output from the pattern generator is sent to the gamma correction circuit 312,
Gamma conversion is performed so as to obtain a desired density, and a patch is formed on the photosensitive drum by the gamma-converted patch image signal.

Here, the gamma conversion characteristic of the gamma correction circuit 312 is appropriately changed by the first control, as described above. Therefore, the patch density formed on the photosensitive drum is adjusted to a preset optimal density by performing the first control.

A patch is formed using the gamma conversion characteristic of the gamma correction circuit 312 newly set in this way,
The detected patch density S (sig-Y) and the reference signal S (i
nt-Y) and the density difference signal S (cal-Y)
Is stored in the memory as a correction value S (adj-Y) of the reference signal, and thereafter, the correction value S (a
dj-Y), a new reference signal S (aint-
The image density detection control described above is performed using Y) as the specified density (initial density) of the patch. This makes it possible to maintain the desired image density and the optimum gradation characteristic corrected by the first control using the image density detection control.

Further, when the first control is performed, the toner density of the developer is in the transition period of the control, and the target value SIG (tgt-Y) newly set by the image density detection control is set.
In most cases, the convergence does not occur. Therefore, in the present embodiment, at the same time as performing the first control, the toner density sensor detects the toner density SIG (ca1-Y) and replaces it with a new target value SIG (tgt-Y). This makes it possible to maintain the desired image density and the optimum gradation characteristics corrected by the first control using the developer density control.

As described above, in this embodiment, the first control controls the image density and the tone reproducibility, and the second control controls the image density and the tone reproducibility.
Further, by adjusting the second control based on the result of the first control, a full-color image can be formed with stable image temperature and gradation reproducibility.

At the same time, when the test print is recorded, a mark for detecting the position such as the type and orientation of the test print is recorded, so that the mark is appropriate for reading the test print or the test print is placed at the correct position. The user can determine whether or not the calibration has been performed, and the user can easily handle the test print with respect to the calibration.

[Second Embodiment] In a second embodiment of the present invention, a test print output by the first control according to the first embodiment is provided with a mark other than the mark for determining the type and position described above. In addition, the time when the test print was output is also recorded, and a predetermined process such as a warning is performed based on the read result. In the following description, only differences from the first embodiment will be described.

In this embodiment, as shown in FIGS. 16 and 17, in the output of the test print 1 and the test print 2, in addition to the marks 1006 and 1109, which are the marks for detecting the type and the position, respectively. Marks 1007 and 1110 for determining the time when the test print was output are recorded together with the patch.

At the time of reading, as shown in FIG. 18, when it is determined that the test pudding has been read correctly (step S103), in step S113, based on the reading result of the mark 1007 shown in FIG. It is determined whether or not a predetermined time has elapsed since the test print 1 was output. If it is determined that the predetermined time has elapsed, a warning message is displayed on the operation panel as shown in FIG. 19A to urge the user to output the test print 1 again (step S1). S10
1). As a result, after a relatively long time has elapsed since the test print was recorded, the state may change from the state when the apparatus outputs the test print, and the calibration based on the test print may not be valid. If there is, the user can be warned that a new test print is output again to perform calibration, and the user can easily manage the test print.

Similarly, the output time of the test print 2 is managed. That is, in FIG. 18, when it is determined that the test print 2 has been correctly read (step S108), the test print 2 is determined in step S114.
It is determined whether or not a predetermined time has elapsed since the is output. Here, if it is determined that the predetermined time has elapsed, a warning message is displayed on the operation panel as shown in FIG. 19B, and the user is prompted to output the test print 2 again (step S106).

On the other hand, if the predetermined time has not elapsed since the output of the test print 2, in step S 115, it is determined whether or not a predetermined time has elapsed from the reading of the test print 1 to the reading of the test print 2. Judge. According to this, it is possible to manage the time from the reading of the test print 1 to the output of the test print 2, particularly the output of the test print 2. In particular, when elapses, it is possible to prevent the calibration based on the test print 1 from becoming inappropriate. If it is determined in step S115 that the predetermined time has elapsed, a warning message is displayed on the operation panel as shown in FIG. 20 to urge the user to start over again from the output of test print 1 (step S101).

According to the present embodiment, it is possible to easily manage the elapsed time from the output of the test print without any trouble for the user.

[Third Embodiment] In a third embodiment of the present invention, in addition to the marks for determining the type and position of the test print shown in the first embodiment, the image forming apparatus which has output the test print is provided. about what to record a mark in order to determine the model.

As shown in FIGS. 21 and 22, each of the test print 1 and the test print 2 has a mark 100 indicating the model that has output the respective test print.
8 and 1111 are recorded with the patch.

Then, as shown in FIG. 23, when reading the test print (step S102), step S1
In step 03, it is determined whether the correct document, that is, the test print 1 is placed on the platen, and whether the test print 1 is placed at a correct position. Is determined to be an image forming apparatus to be subjected to the main calibration. This determination can be made based on the read mark 1008. If it is determined in step S103 that the models are different,
In step S111, the display shown in FIG.
The test print 1 is output by a model different from the model to be calibrated, and the user is prompted again to read the test print 1 output by the model.

The same applies to the case of the test print 2, and the test print 2 is read in step S107. At this time, when it is determined in step S108 that the test print 2 has been output by another model. Is
The message shown in FIG. 24B is displayed, prompting the user to set the correct test print 2 on the platen, and reading is performed again in step S107. Test print 2
It is needless to say that the determination as to whether or not is output by another model is made by the mark 1111 at the time of reading.

As described above, according to the present embodiment, it is possible to easily determine whether or not a model that has output a test print is a model to be calibrated, without requiring the user to manage the model. Becomes possible.

[Other Embodiments] For each mark recorded in the test print described in each of the above embodiments, all or all other combinations are output, and judgment is made based on each mark. And a process corresponding thereto may be performed.

[Embodiment] As described above, the present invention is applied to a system composed of a plurality of devices (for example, a host computer, an interface device, a reader, a printer, etc.), and is applied to a single device (for example, a copying machine). , Facsimile machine).

Also, in order to operate the various devices so as to realize the functions of the above-described embodiments, the devices shown in FIGS. A program code of software for realizing the functions of the embodiment is supplied, and a computer (CPU
Alternatively, the present invention also includes those implemented by operating the various devices according to a stored program.

In this case, the program code of the software implements the functions of the above-described embodiment, and the program code itself and means for supplying the program code to the computer, for example, the program code The stored storage medium constitutes the present invention.

As a storage medium for storing the program code, for example, a floppy (registered trademark) disk, hard disk, optical disk, magneto-optical disk, CD-R
An OM, a magnetic tape, a nonvolatile memory card, a ROM, or the like can be used.

When the computer executes the supplied program code, not only the functions of the above-described embodiment are realized, but also the OS (Operating System) running on the computer or another program code. Needless to say, the program code is also included in the embodiment of the present invention when the functions of the above-described embodiment are realized in cooperation with application software or the like.

Further, the supplied program code is stored in a memory provided in a function expansion board of the computer or a function expansion unit connected to the computer, and then, based on the instruction of the program code, the function expansion board or the function expansion unit. It is needless to say that the present invention includes a case where the CPU or the like provided in the first embodiment performs a part or all of the actual processing, and the processing realizes the functions of the above-described embodiments.

[0132]

As described above, according to the present invention,
When performing calibration for calibrating the recording characteristics of an image forming apparatus that forms an image on a recording medium, the type of the test print and the type of the test print are determined based on the result of reading the test print on which the predetermined image for the calibration is recorded. Check that the test print was read at the correct position.
The time since the test print was output or the model of the image forming apparatus that output the test print is determined, and it is preferable that the test prints are different from each other, If it is determined that the image has not been read at the position, the time after the test print has been output has passed for a predetermined time or more, or if the model of the image forming apparatus is different, the user is notified that fact. In the calibration, the user can read the test print satisfactorily without paying much attention to the handling of the test print.

As a result, the user can appropriately handle test prints for calibration, and can provide a user-friendly image forming apparatus.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a mechanical configuration of a copying machine according to an embodiment of an image forming apparatus of the present invention.

FIG. 2 is a block diagram showing a configuration of image signal processing in the copying machine.

FIG. 3 is a timing chart showing write and read timings of a memory in the image signal processing.

FIG. 4 is a PWM for laser driving in the copying machine.
FIG. 3 is a circuit diagram illustrating signal modulation.

FIG. 5 is a waveform chart for explaining the PWM signal modulation.

[6] automatic gradation correction according to the first embodiment of the present invention
9 is a flowchart illustrating a processing procedure of (calibration).

FIGS. 7A and 7B are diagrams respectively showing display screens for instructing a user to output and read a first test print in the automatic gradation correction processing.

FIGS. 8A and 8B are diagrams respectively showing display screens for instructing a user to output and read a second test print in the automatic gradation correction processing.

FIGS. 9A and 9B are diagrams respectively showing display screens indicating to the user that the two test prints in the automatic gradation correction processing are not set correctly.

FIG. 10 is a diagram showing the first test print.

FIG. 11 is a diagram showing the relationship between the surface potential of the photosensitive drum of the copying machine and the resulting image density.

FIG. 12 is a diagram showing a relationship between a grid potential and a surface potential in a photosensitive drum of the copying machine.

FIG. 13 is a diagram showing a configuration around a photosensitive drum of the copying machine.

FIG. 14 is a diagram illustrating density reproduction characteristics in the copying machine of the present embodiment.

FIG. 15 is a diagram showing the second test print.

FIG. 16 is a diagram showing a first test print according to the second embodiment of the present invention.

FIG. 17 is a diagram showing a second test print according to the second embodiment.

FIG. 18 is an automatic gradation correction according to the second embodiment.
9 is a flowchart illustrating a processing procedure of (calibration).

FIGS. 19A and 19B show display screens showing to the user that a predetermined time has elapsed since the two test prints were output in the automatic gradation correction processing of the second embodiment. FIG.

FIG. 20 is a diagram showing display screens each showing to the user that the output interval between the two test prints in the automatic gradation correction process of the second embodiment is equal to or longer than a predetermined time.

FIG. 21 is a diagram showing a first test print according to a third embodiment of the present invention.

FIG. 22 is a diagram showing a second test print according to the third embodiment.

FIG. 23 is an automatic gradation correction according to the third embodiment.
9 is a flowchart illustrating a processing procedure of (calibration).

FIGS. 24A and 24B show display screens respectively showing to the user that the two test prints in the automatic gradation correction process of the third embodiment are output by different models. FIG.

[Explanation of symbols]

104 brightness / density conversion circuit 106 output masking circuit 112 input masking circuit 208 CCD 212 image processing circuit 217, 221, 225, 229 photosensitive drum 230, 231, 232, 233 developing unit 312 gamma correction circuit 1006, 1109 type and position of test print Detection mark 1007, 1110 Mark indicating the elapsed time from the output of the test print 1008, 1111 Mark indicating the model that has output the test print

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H04N 1/29 H04N 1/29 Z F-term (Reference) 2H027 DA09 DE02 DE07 EA01 EA02 EA05 EA20 EB04 EC03 EC06 EC07 EC20 FB03 FD10 GA23 GA47 GB01 GB07 HA07 ZA07 5C062 AA05 AB05 AB22 AB47 AC04 AC27 AC66 AF06 AF15 AF16 BA00 5C072 AA05 BA20 RA04 RA07 RA18 UA06 XA01 5C074 AA13 BB26 DD07 DD11 DD23 DD28 EE04 EE06 FF15 HH02

Claims (22)

[Claims] An image forming apparatus for forming an image on a recording medium, wherein the image forming apparatus for calibrating the recording characteristics outputs a test print in which a predetermined image for the calibration is recorded on a recording medium. Test print means; and determination means for determining, based on a read result of the test print output by the test print means, a type of the test print and whether the test print has been read at a regular position. Image forming apparatus. 2. The image forming apparatus according to claim 1, wherein the determination unit determines a time from when the test print is output, based on the read result. 3. The image forming apparatus according to claim 1, wherein the determination unit determines a model of the image forming apparatus that has output the test print based on the read result. 4. The method according to claim 1, wherein the determining unit determines that the test print is different, that the test print is not read at a proper position, and that a time after outputting the test print is equal to or longer than a predetermined time. When it is determined that the model of the image forming apparatus is different,
4. The image forming apparatus according to claim 1, further comprising a notifying unit for notifying the user of the fact. 5. The test print means, together with a predetermined image for the calibration, a type of the test print,
A reading position of the test print, a time after outputting the test print, or a mark related to a model of the image forming apparatus is recorded, and the determination unit performs each of the determinations based on a result of reading the mark. The image forming apparatus according to claim 1, wherein the image forming is performed. 6. An image forming apparatus for forming an image on a recording medium, wherein the image forming apparatus for calibrating the recording characteristics outputs a test print in which a predetermined image for the calibration is recorded on the recording medium. An image forming apparatus comprising: a test print unit; and a determination unit configured to determine a time from when the test print is output, based on a read result of the test print output by the test print unit. Wherein said determining means is that the time from the output of said test purine cement is when it is determined that the elapsed predetermined time, which further comprises an informing means for informing the user of the fact The image forming apparatus according to claim 6, wherein: 8. The test print means records a mark relating to the time since the test print was output, together with the predetermined image for calibration, and the determination means based on a read result of the mark. The image forming apparatus according to claim 6, wherein the determination is performed. 9. An image forming apparatus for forming an image on a recording medium, wherein the image forming apparatus calibrates the recording characteristics, and outputs a test print in which a predetermined image for the calibration is recorded on the recording medium. An image forming apparatus comprising: a test print unit; and a determination unit that determines a model of an image forming apparatus that has output the test print based on a read result of the test print output by the test print unit. 10. The image forming apparatus according to claim 9, further comprising a notifying unit for notifying a user when the determining unit determines that the model of the image forming apparatus is different. Forming equipment. 11. The test printing means records a mark relating to the model of the image forming apparatus together with the predetermined image for calibration, and the judging means makes the judgment based on a result of reading the mark. The image forming apparatus according to claim 9, wherein: 12. A calibration method for calibrating recording characteristics of an image forming apparatus for forming an image on a recording medium, comprising: a test print in which a predetermined image for the calibration is recorded on the recording medium by the image forming apparatus. And a step of determining, based on a read result of the output test print, a type of the test print and whether or not the test print has been read at a regular position. 13. The calibration method according to claim 12, wherein the determining step further determines a time from when the test print is output based on the read result. 14. The calibration method according to claim 12, wherein the determining step further determines the model of the image forming apparatus that has output the test print based on the read result. 15. The method according to claim 1, wherein the test print is different, the test print is not read at a proper position, and a time after outputting the test print is equal to or longer than a predetermined time. 15. The calibration method according to claim 12, further comprising a step of notifying a user of the fact that the model is different or that the model of the image forming apparatus is different. . 16. The test print step includes: a type of the test print, a reading position of the test print, a time after outputting the test print, and a time of the image forming apparatus, together with the predetermined image for the calibration. Recording a mark related to the model, and the determining step includes:
16. The method according to claim 12, wherein the determination is made based on a result of reading the mark.
The calibration method according to any one of the above. 17. A calibration method for calibrating a recording characteristic of an image forming apparatus for forming an image on a recording medium, comprising: a test print in which a predetermined image for the calibration is recorded on the recording medium by the image forming apparatus. And a step of judging, based on a read result of the output test print, a time since the test print was output. 18. The method according to claim 18, further comprising the step of, when it is determined that a predetermined time has elapsed since the test print was output, notifying the user of the fact. The method according to claim 17, characterized in that: 19. The test printing step includes recording a mark relating to a time since outputting the test print together with the predetermined image for the calibration, and the determining step includes determining a mark based on a reading result of the mark. 18. The method according to claim 17, wherein the determination is performed.
9. The calibration method according to 8. 20. A calibration method for calibrating recording characteristics of an image forming apparatus for forming an image on a recording medium, comprising: outputting a test print on which a predetermined image for calibration is recorded on a recording medium; A calibration method comprising: determining a model of an image forming apparatus that has output the test print based on a read result of the output test print. 21. The calibration according to claim 20, wherein the determining step further comprises a step of, when determining that the type of the image forming apparatus is different, notifying a user of the determination. Method. 22. The test printing step records a mark relating to the model of the image forming apparatus together with the predetermined image for calibration, and the determining step makes the determination based on a reading result of the mark. 22. The calibration method according to claim 20, wherein: