JP2008233327A - Image forming apparatus and pattern image forming method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily make a pattern image small in size and to decrease toner consumption required to detect toner adhesive amount. <P>SOLUTION: A toner image includes: a first pattern 601 formed on an intermediate transfer belt 104; a second pattern 602 successively formed on the upstream side of the first pattern 601 in the conveying direction DF of the intermediate transfer belt, having the same density as the first pattern 601, and formed in such a state that it extends in a direction having a tilt angle to the conveying direction DF of the intermediate transfer belt and a direction DL orthogonal to the conveying direction DF; and a third pattern 603 successively formed on the upstream side of the second pattern 602 in the conveying direction DF of the intermediate transfer belt, having different density from the first pattern 601, and formed so that width D3 in the direction DL orthogonal to the conveying direction DF may be smaller than the width D1 of the first pattern 601. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electrophotographic image forming apparatus, particularly an image forming apparatus that supplies toner to a developing unit or changes printing conditions, and a pattern image forming method that is executed by the image forming apparatus. The present invention relates to an image forming apparatus having a characteristic shape and a pattern image forming method.

  In a color image forming apparatus, a toner pattern is formed for each color in order to correct a positional deviation of each color, and the positional deviation correction is performed by reading the toner pattern with an optical reading sensor (for example, a pattern density detection sensor). . FIG. 10 is an explanatory diagram showing the relationship between the toner pattern and the sensor spot diameter (detection region) of the reading sensor at this time. By the way, after the toner pattern is formed, it takes a predetermined time until the toner pattern reaches the reading position of the reading sensor. The reading sensor mounting position, the photosensitive drum mounting position, the peripheral speed of the intermediate transfer belt, the reading sensor. Considering each error such as the irradiation position of irradiation light emitted from the light emitting element, the pattern has a width in the main scanning corresponding direction several times larger than the sensor spot diameter of the reading sensor.

  FIG. 10 is a diagram showing a relationship between a toner pattern and a spot diameter according to a conventional example, and FIG. 11 is a characteristic diagram showing a relationship between a density setting value and a toner adhesion amount. As shown in FIG. 10, the size of the toner pattern 201 is increased in anticipation of errors in the mounting position of the reading sensor, the photosensitive drum 2, etc., and the toner pattern 201 is reliably scanned to ensure reading of the toner pattern 201. It was. Then, the toner adhesion amount is calculated based on the density output value read in this way. FIG. 11 is a characteristic diagram showing the amount of adhesion calculated based on the read density output value.

However, when the size of the toner pattern 201 is increased in this way, not only the toner is consumed, but also the position where the toner pattern is formed is limited. Therefore, for example, the invention disclosed in Patent Document 1 is detected by a detection sensor for the purpose of reducing toner consumption by density control and improving the density detection accuracy. A correction value, which is a temporal difference between the detection timing of the registration control patch obtained from the registration position detection information and the detection timing of the registration control patch calculated in advance, is obtained by the control device, and the transfer is performed based on the correction value. The formation position of the density control patch formed on the material transport belt is corrected. This makes it possible to use a density control patch having a minimum size, thereby reducing the amount of toner consumed by the density control and further improving the density detection accuracy.
JP 2001-209292 A

  In the invention of Patent Document 1, a correction value that is a temporal difference between the detection timing of the registration control patch obtained from the registration position detection information detected by the detection sensor and the detection timing of the registration control patch calculated in advance. Is determined by the control device, and the formation position of the density control patch formed on the transfer material transport belt is corrected based on the correction value. However, the correction value is actually one image forming apparatus. The color image forming apparatus has four colors, and it is necessary to repeat the same operation for each of them, which is inefficient.

  Therefore, the problem to be solved by the present invention is to make it possible to easily reduce the size of the pattern image and to reduce the amount of toner consumption required for detecting the toner adhesion amount.

  In order to solve the above-mentioned problem, the first means includes an image forming means for supplying toner onto an image carrier to form a toner image, a detection means for detecting the toner image and outputting a detection signal, Calculating means for calculating the toner amount or toner density attached to the toner image based on a detection signal; and condition setting means for setting an image forming condition of the image forming means based on the toner amount or toner density. The toner image is sequentially formed on the upstream side of the first pattern with respect to the first pattern formed on the image carrier and the conveyance direction of the image carrier, The same density as the first pattern, and the direction (hereinafter referred to as the sub-scanning direction) of the image carrier and the direction orthogonal to the direction of conveyance of the image carrier (hereinafter referred to as main running). A second pattern formed in a state extending in a direction having an inclination angle in a corresponding direction), and sequentially formed upstream of the second pattern in the transport direction of the image carrier. And a third pattern having a density different from that of the first pattern and having a width in the main scanning corresponding direction narrower than that of the first pattern.

  According to a second means, in the first means, the pattern formed upstream of the third pattern has a main scanning corresponding direction width that is the same as a main scanning corresponding direction width of the third pattern, and the density is The density of the first pattern is different from the density of the third pattern.

  The third means is characterized in that, in the first or second means, the width in the main scanning direction of the first pattern is set to a width including one or more detection areas of the detection means. .

  The fourth means is characterized in that, in the first or second means, the width in the sub-scanning corresponding direction of the first pattern is set to a width including one or more detection areas of the detection means. .

  According to a fifth means, in the first or second means, the width orthogonal to the longitudinal direction of the second pattern is set to be narrower than the width corresponding to the main scanning direction of the first pattern. Features.

  A sixth means is characterized in that, in the first or second means, the width orthogonal to the longitudinal direction of the second pattern is set to a width including one or more detection regions of the density detection means. And

  The seventh means is the first or second means, wherein the second pattern has an inclination angle in the main scanning corresponding direction and the sub-scanning corresponding direction in the region including one or more detection regions of the detecting means. It is characterized by being formed continuously in a direction.

  According to an eighth means, in the first or second means, the sub-scan corresponding direction width of the third pattern is set to be narrower than the sub-scan corresponding direction width of the first pattern. Features.

  The ninth means is characterized in that, in the first or second means, the sub-scanning corresponding direction width of the third pattern is set to a width including one or more detection areas of the detection means. .

  According to a tenth means, in the first or second means, the width in the main scanning corresponding direction of the third pattern is set to a width having an area including one or more detection areas of the detection means. Features.

  The eleventh means is characterized in that, in the first or second means, the time interval between the patterns formed by the image forming means is longer than the time for the condition switching of the condition setting means.

  In a twelfth means, in the first or second means, the position at which the density value of the first pattern detected by the detecting means is equal to the density value of the second pattern is The pattern formation center position in the direction corresponding to the main scan of the pattern 3 is characterized.

  In a thirteenth means, in the first or second means, the position at which the density value of the first pattern detected by the detection means is equal to the density value of the second pattern is The pattern formation center position in the main scanning corresponding direction of the pattern formed upstream of the third pattern is characterized in that

  The fourteenth means is the first or second means, wherein the first pattern, the second pattern, the third pattern, and the pattern formed upstream of the third pattern are: It is characterized by being formed in order from the image forming color that is closest to the detection means.

  A fifteenth means is characterized in that, in the first or second means, the inclination angle in the longitudinal direction of the second pattern is ± 45 ° with respect to the conveying direction of the image carrier.

  According to a sixteenth aspect, in the first or second means, the density of the first pattern determined by the image forming means is a central value of density values of all patterns used in the arithmetic means. It is characterized by.

  The seventeenth means is the first or second means, wherein the detection means irradiates the position of each pattern formed on the image carrier with light, and the reflected light from each pattern. It comprises an optical sensor provided with a light receiving portion for receiving light.

  An eighteenth means is characterized in that, in the first or second means, the image carrier is an intermediate transfer belt.

  A nineteenth means is characterized in that, in the first or second means, a positional deviation of each color in the main scanning correspondence direction is corrected based on the detection result.

  In the twentieth means, in the first or second means, the area of the third pattern and the area of the pattern formed upstream of the third pattern are detected in the image data to be printed. Then, density detection is performed using the detection means.

  A twenty-first means forms the pattern formed upstream of the third pattern and the third pattern in a place where the respective patterns cannot be continuously formed in the first or second means. It is characterized by.

  A twenty-second means is characterized in that, in the twenty-first means, the place where the respective patterns cannot be formed continuously is between the sheets.

  A twenty-third means includes a step of supplying a toner on the image carrier to form a toner image, a step of detecting the toner image and outputting a detection signal, and a detection step based on the detection signal. A pattern image forming method comprising: a step of calculating a toner amount or a toner density adhered to a toner image; and a step of setting an image forming condition of the image forming unit based on the toner amount or the toner concentration. In the image forming step, the first pattern is sequentially formed on the image carrier on the upstream side of the first pattern in the transport direction of the image carrier, and the same density as the first pattern is formed. And a second pattern extending in a direction having an inclination angle in a sub-scanning direction of the image carrier and a main scanning direction of the image carrier, Are sequentially formed on the upstream side of the second pattern, the density is different from that of the first pattern, and the width in the main scanning corresponding direction is narrower than that of the first pattern. It is characterized by a pattern image forming method for forming each of the third patterns.

  In the embodiments described later, the image forming means is in the developing unit 105, the detection means is in the pattern density detection sensor 107, the calculation means and condition setting means are in the control means 113, the image carrier is in the intermediate transfer belt 104, The first pattern corresponds to the reference numeral 601, the second pattern corresponds to the reference numeral 602, and the third pattern corresponds to the reference numeral 603.

  According to the present invention, it is possible to reduce the size of the pattern image and reduce the amount of toner consumed by adding only one oblique pattern.

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

  FIG. 1 is a diagram illustrating a schematic configuration of an image forming apparatus according to an embodiment of the present invention. The image forming apparatus 100 according to the present embodiment includes a paper feed cassette 101, a paper feed roller 102, a conveyance path 103, an intermediate transfer belt 104, and development units 105K, 105C, and 105M provided for each color K, C, M, and Y. , 105Y, photoconductors 106K, 106C, 106M, 106Y, pattern density detection sensor 107, tension roller 108, driving roller 109, cleaning device 110, secondary transfer roller 111, and fixing unit 112.

  The paper feed cassette 101 stacks paper before printing. The paper feed roller 102 feeds the paper stacked in the paper feed cassette 101 to the transport path 103 in order from the topmost paper. The sheets that are separated and fed one by one are conveyed to the secondary transfer roller 111 in accordance with the timing at which the image on the intermediate transfer belt 104 is transferred. The intermediate transfer belt 104 is a belt wound around a driving roller 109 and a tension roller 108, is driven by the driving roller 109, and is given a predetermined tension by the tension roller 108.

  The image forming apparatus 100 in FIG. 1 is a so-called tandem type that includes a configuration in which development units 105K, 105M, 105C, and 105Y of complementary colors are arranged along the intermediate transfer belt 104. K represents black, M represents magenta, C represents cyan, and Y represents yellow. Each of the developing units 105K, 105M, 105C, and 105Y includes photosensitive members 106K, 106M, and 106C that can carry toner images of KMCY toner. 106Y is provided.

  In FIG. 1, the intermediate transfer belt 104 rotates counterclockwise, and a plurality of developing units 105K, 105M, 105C, and 105Y are arranged in order from the upstream side in the rotation direction. The plurality of developing units 105K, 105M, 105C, and 105Y have the same internal configuration except that the color of the toner image to be formed is different. In the following description, the contents common to all the developing units or all the photoconductors are expressed as the developing unit 105 or the photoconductor 106.

  When forming an image, the outer peripheral surface of the photoreceptor 106 is uniformly charged in the dark. After that, the outer peripheral surface of the uniformly charged photoreceptor 106 is exposed by irradiating laser light corresponding to each color image. Thereby, an electrostatic latent image is formed. By making this electrostatic latent image visible, a toner image of each color is formed on the photoreceptor 106. This toner image is transferred onto the intermediate transfer belt 104 by a primary transfer roller (not shown) at a position (primary transfer position) where the photosensitive member 106 and the intermediate transfer belt 104 are in contact with each other. By this transfer, an image of toner is formed on the intermediate transfer belt 104.

  The intermediate transfer belt 104 to which the black toner image is transferred by the developing unit 105K as described above is conveyed to the next developing unit 105M when a color printing request is made. In the developing unit 105M, a magenta toner image is formed on the photoreceptor 106M by a process similar to the image forming process in the developing unit 105K, and the toner image is superimposed on the black image formed on the intermediate transfer belt 104. Is transcribed. The intermediate transfer belt 104 is further conveyed to the next developing units 105C and 105Y, and a cyan toner image formed on the photoconductor 106C and a yellow toner image formed on the photoconductor 106Y by the same operation. Is superimposed and transferred onto the intermediate transfer belt 104. In this way, a full color image is formed on the intermediate transfer belt 104.

  The intermediate transfer belt 104 on which the full-color superimposed image is formed is conveyed to the position of the secondary transfer roller 111, and the full-color image on the intermediate transfer belt 104 is transferred from the paper feed cassette 101 by the action of the secondary transfer roller 111. It is transferred to the conveyed paper.

  FIG. 2 is an enlarged view of the pattern density detection sensor portion of FIG. 1. The pattern density detection sensor 107 reads the density of the pattern image 201 on the intermediate transfer belt 104. The pattern density detection sensor 107 is a light reflection type sensor including a light emitting element 202 and a light receiving element 203, and one pattern density detection sensor 107 is provided. Further, after the transfer of the toner image is completed on the surface of the intermediate transfer belt 104, unnecessary toner remaining without being transferred onto the sheet is removed by the cleaning device 110, and the apparatus waits for the next image formation.

  The fixing unit 112 thermally fuses the toner image transferred to the paper and fixes the toner image to the paper. The fixing unit 112 operates when the temperature is raised to a temperature equal to or higher than a threshold value by another driving source (not shown). Then, the sheet on which the toner image is fixed by the fixing unit 112 is discharged out of the image forming apparatus 100 as a printing result. In the image formation, in the case of black-only printing (monochrome printing), the photoreceptor 106M, the photoreceptor 106C, and the photoreceptor 106Y are retracted to positions separated from the intermediate transfer belt 104, and the above-described image formation process is performed in black. Run only if.

  FIG. 3 is a block diagram showing a circuit configuration of the toner adhesion amount detection circuit. The detection circuit includes the pattern density detection sensor 107 and control means (control circuit including a CPU) 113. The control unit 113 emits illumination light from the light emitting element 202, and the reflected light from the image carrier (here, the intermediate transfer belt 104) or the toner pattern image 201 is received by the light receiving element 203 and received by the control unit 113. Based on the signal level of the detection signal input from the element 203, the toner adhesion amount of the n pattern images 201 formed on the intermediate transfer belt 104 is calculated. Note that n pattern images 201 are formed on the intermediate transfer belt 104 by developing units 105K, 105M, 105C, and 105Y as image pattern forming means. Pattern image formation control is also performed by the control means 113. The control unit 113 functions as a calculation unit that calculates the toner amount or the toner density attached to the toner image based on the detection signal obtained by the pattern density detection sensor 107 detecting the reflected light from the pattern image 201. It also functions as a condition setting unit that sets image forming conditions for an image formed by the image forming process based on the toner amount or the toner density.

4 and 5 are explanatory views showing the state of toner image (pattern image) formation according to this embodiment.
As shown in FIGS. 4 and 5, the toner image includes a first pattern 601 formed on the intermediate transfer belt (image carrier) 104 and a conveyance direction of the intermediate transfer belt 104 (hereinafter referred to as a sub-scanning corresponding direction). The DF is sequentially formed on the upstream side of the first pattern 601 and has the same density as the first pattern 601 and the sub-scanning corresponding direction DF of the intermediate transfer belt 104 and the intermediate transfer belt 104. A second pattern 602 formed in a state extending in a direction having an inclination angle in a direction perpendicular to the conveyance direction DF (hereinafter also referred to as a main scanning corresponding direction) DL, and the conveyance direction DF of the intermediate transfer belt 104 are the first. Are formed sequentially upstream of the second pattern 602, have a density different from that of the first pattern 601, and have a width D3 in the main scanning corresponding direction DL. It comprises a narrow third pattern 603 than the width D1 of the first pattern. These patterns form the second pattern 602 after forming the first pattern 601. Next, the result obtained by calculating the toner amount or toner density in the first pattern 601 by the control circuit 113 is compared with the result obtained by calculating the toner amount or toner density in the second pattern 602 by the calculating means in the control circuit 113. The position of the pattern density detection sensor 107 in the main scanning corresponding direction DL is calculated from the comparison result. After the third pattern 603, a third pattern 603 having a width D3 that matches the sensor spot diameter DS of the sensor spot SP based on the calculated position corresponding to the main scanning direction of the pattern density detection sensor 107 is formed.

  The pattern 604 formed upstream of the third pattern 603 has a main scanning corresponding direction width D4 that is the same as the main scanning corresponding direction width D3 of the third pattern 601, and the density is equal to the density of the first pattern. The density is set to be different from the density of the third pattern.

  The width D1 in the main scanning correspondence direction of the first pattern 601 is set to a width that includes one or more detection areas of the pattern density detection sensor 107. Similarly to the main scanning-corresponding direction width D1, the sub-scan corresponding direction width F1 of the first pattern 601 is also set to a width that includes one or more detection areas (equal to the sensor spot diameter DS) of the pattern density detection sensor 107. ing.

  The width D2 orthogonal to the longitudinal direction of the second pattern 602 is set to be narrower than the width D1 in the main scanning corresponding direction of the first pattern 601, and one detection area of the pattern density detection sensor 107 is provided. This is the width included. In this case, in the second pattern 602, the area AR2 including one or more detection areas DS of the pattern density detection sensor 107 is continuous in a direction having an inclination angle in the main scanning corresponding direction DL and the sub scanning corresponding direction DF. Set to.

  Furthermore, the sub-scan corresponding direction width F3 of the third pattern 603 is narrower than the sub-scan corresponding direction width F1 of the first pattern 601, and includes a width that includes one or more detection regions DS of the pattern density detection sensor 107. To do. Also, the main scan corresponding direction width D3 of the third pattern 603 is set to a width including one or more detection areas DS of the pattern density detection sensor 107, similarly to the sub-scan corresponding direction width F3.

  The time interval between the patterns formed on the intermediate transfer belt 104 is set by the control unit 113, but is set longer than the time required for switching the image forming conditions set by the control unit 113. .

  The pattern formation center position of the third pattern 603 in the main scanning corresponding direction is equal to the density value of the first pattern 601 detected by the pattern density detection sensor 107 and the density value of the second pattern 602. The position is the pattern formation center position of the third pattern 603 in the main scanning corresponding direction DL. Thereby, even if a positional deviation occurs in the main scanning correspondence direction DL, the positional deviation is detected when the second pattern 602 is read, and the third pattern 603 is formed at the shifted position. The density information can be surely obtained from the first to third patterns 601, 602 and 603.

  The pattern formation center position in the main scanning correspondence direction DL of the pattern 604 formed upstream of the third pattern 603 is also the first pattern 601 detected by the pattern density detection sensor 107 in the same manner as the third pattern 603. A position where the density value of the second pattern 602 becomes equal to the density value of the second pattern 602 is set as a pattern formation center position in the main scanning corresponding direction of the pattern 604 formed upstream of the third pattern. As a result, even if a positional deviation occurs in the main scanning corresponding direction, the positional deviation is detected when the second pattern 602 is read, and the pattern 604 upstream of the third pattern 603 is also in the shifted position. Since it is formed, it is possible to reliably obtain the density information of the first to third patterns 601, 602, 603 and the pattern formed on the upstream side.

  The first pattern 601, the second pattern 602, the third pattern 603, and the pattern 604 formed upstream of the third pattern 603 are based on the image forming color that is closest to the pattern density detection sensor 107. Form.

  The inclination angle in the longitudinal direction of the second pattern 602 is set to ± 45 ° with respect to the conveyance direction (sub-scanning direction) of the intermediate transfer belt 104. This facilitates calculation of the shift amount of the pattern density detection sensor 107 in the main scanning corresponding direction DL.

  The density of the first pattern 601 is the center value of the density values of all patterns used in the calculation means. Thereby, the density can be evaluated based on the density of the first pattern 601.

  The pattern shown in FIG. 4 and the pattern shown in FIG. 5 differ in the length of the third pattern 603 and the pattern 604 formed upstream of the third pattern 603 in the sub-scanning corresponding direction DF. As shown in FIG. 4, when the length of the sub-scanning corresponding direction DF after the third pattern 603 is long, the information obtained from the pattern image increases, but the amount of toner consumed also increases. On the other hand, when the length is short as shown in FIG. 5, less information is obtained from the pattern image, but the amount of toner consumed is small and economical. Therefore, the length of the sub-scanning corresponding direction DF is determined in consideration of these points.

  As described above, the shift amount in the main scanning direction can be detected from the detection position of the second pattern 602 when the pattern after the third pattern 603 shown in FIG. 4 or 5 is formed. . 6 and 7 are diagrams showing the detection results. That is, when a pattern is viewed for each color, a shift occurs in the sub-scanning corresponding direction for each color pattern. Therefore, as can be seen from the figure, when the black image pattern forming position is used as a reference, the position information in the main scanning correspondence direction for each of the colors yellow, cyan, and magenta with the center position in the black main scanning correspondence direction as a reference. By comparing, the displacement distance from the reference position can be calculated, and the displacement correction in the main scanning correspondence direction can be performed based on the calculation result. This correction is executed by the CPU in the control means 113.

  Further, as shown in FIG. 8, the area of the third pattern 603 and the area of the pattern 604 formed upstream of the third pattern 603 are included in the print data (image data D to be printed). When the pattern area control unit set in the control unit 113 detects, the density of the patterns 603 and 604 can be detected by the toner density detection sensor 107 to correct the data. In this case, the diameter range of the spot diameter scanned by the toner density detection sensor 107 becomes the image formation area AR of a new pattern (patch).

  As a result, it is possible to reduce the size of the pattern image, shorten the work time required for detecting the toner adhesion amount, reduce the toner consumption amount, and maintain the print quality.

  Since the pattern image can be miniaturized as described above, even when the pattern cannot be continuously generated as between the sheets, the third pattern 603 and the third pattern between the sheets as shown in FIG. The pattern 604 formed upstream of the third pattern 603 is formed, and the same detection and correction can be performed. As a result, pattern formation and pattern detection are possible even in a narrow area such as a gap between sheets, which was difficult with the conventional pattern, and it is possible to cope with a high-speed machine with a short interval between sheets.

1 is a diagram illustrating a schematic configuration of an image forming apparatus according to an embodiment of the present invention. It is a figure which shows schematic structure of the pattern density detection sensor in embodiment of this invention. FIG. 5 is a block diagram showing a processing configuration when detecting the amount of toner adhesion using a pattern density detection sensor. FIG. 6 is a diagram illustrating a relationship between a pattern image formed on an intermediate transfer belt and a sensor spot diameter in the present embodiment. FIG. 6 is a diagram illustrating a relationship between a pattern image formed on an intermediate transfer belt and a sensor spot diameter in another example of the embodiment. It is explanatory drawing of the control which correct | amends the position shift between each color in the main scanning corresponding | compatible direction from the pattern image obtained in this embodiment. It is explanatory drawing of the control which correct | amends the position shift between each color in the main scanning corresponding | compatible direction from the pattern image obtained in the other example of this embodiment. It is explanatory drawing which shows the state which detects the pattern image obtained by this embodiment within the image data of printing object. It is explanatory drawing which shows the state which performs density control between sheets using the pattern image obtained by this embodiment. It is a figure which shows the relationship between the pattern image formed on the intermediate transfer belt in a prior art example, and a sensor spot diameter. It is a figure which shows the relationship between the toner density setting value in a pattern density detection sensor, and the toner adhesion amount.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Image forming apparatus 101 Paper feed cassette 102 Paper feed roller 103 Conveying path 104 Intermediate transfer belt 105 Development unit (K, C, M, Y)
106 photoconductor (K, C, M, Y)
107 Pattern Density Detection Sensor 108 Tension Roller 109 Drive Roller 110 Cleaning Device 111 Secondary Transfer Roller 112 Fixing Unit 113 Controller 201 Toner 202 Light Emitting Element 203 Light Receiving Element 601 First Pattern 602 Second Pattern 603 Third Pattern DS Sensor Spot diameter SP Sensor spot

Claims (23)

Image forming means for forming a toner image by supplying toner onto the image carrier;
Detecting means for detecting the toner image and outputting a detection signal;
A calculation means for calculating the amount of toner or the toner density attached to the toner image based on the detection signal;
Condition setting means for setting an image forming condition of the image forming means based on the toner amount or the toner density;
An image forming apparatus comprising:
The toner image includes a first pattern formed on the image carrier,
The image carrier is sequentially formed on the upstream side of the first pattern in the transport direction, and has the same density as the first pattern, and the transport direction of the image carrier (hereinafter referred to as a sub-scanning corresponding direction). And a second pattern formed in a state extending in a direction having an inclination angle in a direction orthogonal to the conveyance direction of the image carrier (hereinafter referred to as a main scanning corresponding direction);
It is sequentially formed on the upstream side of the second pattern in the conveyance direction of the image carrier, has a density different from that of the first pattern, and the width in the main scanning corresponding direction is that of the first pattern. A narrower third pattern,
An image forming apparatus comprising:   The pattern formed upstream of the third pattern has a main scanning corresponding direction width that is the same as the third pattern corresponding to the main scanning corresponding direction width, and the density is the first pattern density and the third pattern. The image forming apparatus according to claim 1, wherein the image forming apparatus is set to a density different from the density of the pattern.   3. The image forming apparatus according to claim 1, wherein a width corresponding to a main scanning direction of the first pattern is set to a width including at least one detection region of the detection unit. .   3. The image forming apparatus according to claim 1, wherein the width in the sub-scanning corresponding direction of the first pattern is set to a width including at least one detection region of the detection unit. .   3. The image according to claim 1, wherein a width orthogonal to a longitudinal direction of the second pattern is set to be narrower than a width in a main scanning corresponding direction of the first pattern. 4. Forming equipment.   3. The image according to claim 1, wherein a width orthogonal to a longitudinal direction of the second pattern is set to a width including at least one detection region of the density detection unit. Forming equipment.   3. The second pattern according to claim 1, wherein the second pattern includes a region in which one or more detection regions of the detection unit are included in a direction having an inclination angle in a main scanning corresponding direction and a sub scanning corresponding direction. The image forming apparatus according to any one of the above.   3. The image according to claim 1, wherein a width in the sub-scanning corresponding direction of the third pattern is set to be narrower than a width in the sub-scanning corresponding direction of the first pattern. Forming equipment.   3. The image forming apparatus according to claim 1, wherein a width in the sub-scanning corresponding direction of the third pattern is set to a width including at least one detection region of the detection unit. .   The width in the main scanning correspondence direction of the third pattern is set to a width having an area including one or more detection areas of the detection unit. Image forming apparatus.   3. The image according to claim 1, wherein the time interval between the patterns formed by the image forming unit is set to be longer than the time required for the condition switching of the condition setting unit. Forming equipment.   The position where the density value of the first pattern detected by the detection means is equal to the density value of the second pattern is the pattern formation center position in the main scanning corresponding direction of the third pattern. The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus.   Corresponding to the main scan of the pattern formed upstream of the third pattern, the position where the density value of the first pattern and the density value of the second pattern detected by the detection means are equal. The image forming apparatus according to claim 1, wherein the image forming apparatus has a pattern formation center position in the direction.   The first pattern, the second pattern, the third pattern, and the pattern formed upstream of the third pattern are formed in order from the image forming color closest to the detection means. The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus.   The image forming apparatus according to claim 1, wherein an inclination angle in a longitudinal direction of the second pattern is ± 45 ° with respect to a conveyance direction of the image carrier.   3. The density of the first pattern determined by the image forming unit is set to a central value of density values of all patterns used by the calculation unit. The image forming apparatus described in 1.   The detection means is an optical sensor including a light emitting unit that irradiates light to a position of each pattern formed on the image carrier and a light receiving unit that receives reflected light from each pattern. The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus.   The image forming apparatus according to claim 1, wherein the image carrier is an intermediate transfer belt.   The image forming apparatus according to claim 1, wherein a position shift of each color in the main scanning corresponding direction is corrected based on the detection result.   When detecting the area of the third pattern and the area of the pattern formed upstream of the third pattern in the image data to be printed, density detection is performed using the detection means. The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus.   The said pattern formed upstream of the said 3rd pattern and the said 3rd pattern is formed in the place which cannot form each said pattern continuously, Either of Claim 1 and Claim 2 characterized by the above-mentioned. The image forming apparatus described.   The image forming apparatus according to claim 21, wherein the place where the patterns cannot be continuously formed is between sheets. Supplying toner onto the image carrier to form a toner image;
Detecting the toner image and outputting a detection signal;
Calculating a toner amount or a toner concentration attached to the toner image based on the detection signal;
Setting image forming conditions of the image forming means based on the toner amount or the toner density;
A pattern image forming method comprising:
In the step of forming the toner image,
A first pattern on the image carrier,
The image carrier is sequentially formed on the upstream side of the first pattern with respect to the conveyance direction of the image carrier, and has the same density as the first pattern and corresponds to the sub-scanning direction of the image carrier and the image carrier. A second pattern extending in a direction having an inclination angle in the main scanning corresponding direction,
It is sequentially formed on the upstream side of the second pattern in the conveyance direction of the image carrier, has a density different from that of the first pattern, and has a width in the main scanning corresponding direction of the first pattern. The third pattern to be narrower than that,
A pattern image forming method comprising forming each of them.

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